25 Ocak 2012 Çarşamba
Why the WKPP and GUE do bottle marking the way they do By George Irvine
The big risk in gas diving is breathing the wrong gas. The WKPP developed as part of its overall system a simple methodolgy for preventing this.
11 Ocak 2012 Çarşamba
Why we wear our stages on the left? (by Team Foxturd)
Our standard switching procedure includes the following
steps: Signal to switch, cylinder is prepared, diver checks markings and depth,
buddy checks cylinder markings and depth and gives ok, diver then switches,
confirming switch to team. What this sequence entails is that any particular
placement of cylinders plays absolutely no role in choosing which cylinder we
switch to. Therefore any richie-righty lefty-leany or any other similar rules
become irrelevant.
Now, on to our reasoning behind having cylinders on the left. First, let's take a quick look at some of our gear and think about how it all comes together:
[*]Our stage/deco cylinders are exclusively aluminium, not steel.
[*]On our right hip we carry the canister of our primary light.
[*]Our long hose is our primary hose, ie we are breathing from it. Hence it goes over our right shoulder, under the light canister on our right hip, diagonally up over our chest, around the neck to the mouth.
[*]Our primary light head is carried on the left hand when deployed, and clipped off on the right shoulder d-ring when stowed.
[*]Our stage/deco cylinders have a regulator fitted with a 1m hose (more on that in a tick)
[*]We have two shoulder D-rings, one on each side.
Now, to elaborate on the above list point by point:
Since we use exclusively aluminium stages, we can never be so off balance that it becomes a serious comfort issue. On our left side we clip a maximum of 2 cylinders, with any additional ones being attached to a "leash", which puts them more or less centrally positioned on top of our backside when full, or when empty floating gently out of the way. We know from experience that aluminium stages, even several, when used correctly do not make a diver unbalanced.
The canister light on the right hip is convenient, since it provides a comfortable way of holding the long hose in place, its weight provides some balance to our gear, and its position on the right, non-buckle side of the strap means it can be easily ditched in case of a bouyancy emergency. There really is no room for a D-ring, and even if we were to add one in some awkward way, a cylinder on the right side would probably cause damage to the canister or the cable coming out of it.
The way we route the long hose achieves several things: It is easy to quickly donate to our buddy in case of an OOG emergency, the hose is kept out of the way, the hose is unlikely to come loose when we don't want it to, and it won't get tangled or entrapped in other parts of our gear. A cylinder on the right side is incompatible with our long hose routing. The long hose would inevitably become trapped by the cylinder, making gas donation a very complicated maneuver.
The primary light must be easy to deploy and stow during the dive. There should be no entrapment of it, and we must be able to manage it while donating the long hose in a gas emergency. We can't have stage rigging getting in the way. When stowing or deploying the primary light we don't want our right d-ring to be cluttered.
The stages are equipped with a 1m hose so that we can wrap the hose around our neck just like the long hose. This fullfills two functions: The hose is snug against our body and so is unlikely to snag, and secondly in case of an OOG emergency we can donate the regulator from our mouth using exactly the same well-practiced method we would when breathing the long hose. To do this from the right would require longer hoses. Just what we don't need; different stage reg hose lengths for each side.
Now for the shoulder d-rings: The d-rings have limited real-estate on them, lets see what a fully rigged DIR diver has on each one: LEFT: 2x stage cylinder bolt-snaps, 1 x backup light bolt-snap, total:3. Right: 1 x backup light bolt-snap, 1 x spare double-ended snap (for primary light), 1 x primary light bolt-snap, and finally the primary regulator is clipped off here when we aren't using it. So that's a total of up to 4 items clipped to the right shoulder d-ring - do we really have space for more?
Now add the scooter into the equation....
Now, on to our reasoning behind having cylinders on the left. First, let's take a quick look at some of our gear and think about how it all comes together:
[*]Our stage/deco cylinders are exclusively aluminium, not steel.
[*]On our right hip we carry the canister of our primary light.
[*]Our long hose is our primary hose, ie we are breathing from it. Hence it goes over our right shoulder, under the light canister on our right hip, diagonally up over our chest, around the neck to the mouth.
[*]Our primary light head is carried on the left hand when deployed, and clipped off on the right shoulder d-ring when stowed.
[*]Our stage/deco cylinders have a regulator fitted with a 1m hose (more on that in a tick)
[*]We have two shoulder D-rings, one on each side.
Now, to elaborate on the above list point by point:
Since we use exclusively aluminium stages, we can never be so off balance that it becomes a serious comfort issue. On our left side we clip a maximum of 2 cylinders, with any additional ones being attached to a "leash", which puts them more or less centrally positioned on top of our backside when full, or when empty floating gently out of the way. We know from experience that aluminium stages, even several, when used correctly do not make a diver unbalanced.
The canister light on the right hip is convenient, since it provides a comfortable way of holding the long hose in place, its weight provides some balance to our gear, and its position on the right, non-buckle side of the strap means it can be easily ditched in case of a bouyancy emergency. There really is no room for a D-ring, and even if we were to add one in some awkward way, a cylinder on the right side would probably cause damage to the canister or the cable coming out of it.
The way we route the long hose achieves several things: It is easy to quickly donate to our buddy in case of an OOG emergency, the hose is kept out of the way, the hose is unlikely to come loose when we don't want it to, and it won't get tangled or entrapped in other parts of our gear. A cylinder on the right side is incompatible with our long hose routing. The long hose would inevitably become trapped by the cylinder, making gas donation a very complicated maneuver.
The primary light must be easy to deploy and stow during the dive. There should be no entrapment of it, and we must be able to manage it while donating the long hose in a gas emergency. We can't have stage rigging getting in the way. When stowing or deploying the primary light we don't want our right d-ring to be cluttered.
The stages are equipped with a 1m hose so that we can wrap the hose around our neck just like the long hose. This fullfills two functions: The hose is snug against our body and so is unlikely to snag, and secondly in case of an OOG emergency we can donate the regulator from our mouth using exactly the same well-practiced method we would when breathing the long hose. To do this from the right would require longer hoses. Just what we don't need; different stage reg hose lengths for each side.
Now for the shoulder d-rings: The d-rings have limited real-estate on them, lets see what a fully rigged DIR diver has on each one: LEFT: 2x stage cylinder bolt-snaps, 1 x backup light bolt-snap, total:3. Right: 1 x backup light bolt-snap, 1 x spare double-ended snap (for primary light), 1 x primary light bolt-snap, and finally the primary regulator is clipped off here when we aren't using it. So that's a total of up to 4 items clipped to the right shoulder d-ring - do we really have space for more?
Now add the scooter into the equation....
Anatomy of the Valve Drill (by Team Foxturd)
This article outlines the process and
reasoning behind the DIR valve drill, as understood by myself. firstly, a
caveat. This is my interpretation of the valve drill, and my thought process
behind it. If you want to learn how to do it officially, then you need to take a course, or speak to an instructor.
Process summary
The basic valve drill involves closing and opening all three posts on a twin set starting with the right post, then the isolator, then the left post.
Process Details
1. Signal to your team you are going to perform a valve drill
2. Wait until your team is in place and then continue
3. Purge Backup regulator
4. Shut down the right hand post whilst simultaneously signalling you are manipulating a valve to your team
5. when the post is shut down, breathe down the regulator until it "locks".
6. Remove the regulator and replace with your backup regulator
7. clip off your primary regulator on the right chest D ring
8. Open the Right post
9. Unclip the primary regulator and purge it
10. Remove the backup regulator from your mouth and replace with the primary regulator
11. Shut down the Isolator whilst simultaneously signalling you are manipulating a valve to your team
12. When the Valve is closed, Re-open the isolator
13. Move your torch to your right hand
14. Shut down the left hand post whilst simultaneously signalling you are manipulating a valve to your team
15. When the post is closed, purge the backup regulator until it "locks"
16. Open the left post
17. Move the torch to your left hand.
18. Check the position of your right hand post
19. Check the position of your isolator
20. Move the torch to your right hand and check the position of your left post
21. Signal that your drill is complete
Looks like a lot of steps, but it really should not take you any more than a minute or so to go through the drill in a nice slow fashion, and I've seen people do it a great deal quicker than this. The trick is to go through the drill slowly and carefully again and again until the movements become muscle memory rather than conscious action. At that point, you can begin to speed up the drill until it becomes both smooth and fast.
Anatomy of the process
Now that we understand the steps we have to take in order to complete the drill, let's look at each step in a little more detail and explain some of the reasoning behind it.
1. Signal to your team you are going to perform a valve drill
OK, so we are diving in a two or a three. We signal to the rest of the team that we are going to do a drill. This means a clear point at all the other team members indicating "You!" and "You", then pointing at your mask indicating "watch me", and then a turning motion with both hands indicating valve drill, hence "You! Watch Me!" "Do a Valve Drill!". this is critical as the rest of the team need to know what is going on so that they are ready if there is a problem. A problem could be you shutting down both posts and leaving yourself out of gas, or something going wrong with your kit. In either situation they need to be ready to step in, and critically, they need to be doing nothing else but watch so that they are not doing any other drills at this time.
2. Wait until your team is in place and then continue
If you are swimming in a line, you need to give your team time to get into a triangle formation all pointing inwards so that they can see you, and see your valves. This is important so that they are in the correct position to donate a long hose if they need to, and so that they can follow your movements on your valves. so have patience and let them get ready before you get going. Once you are all in position, you maintain eye contact with your team. This is done to ensure that firstly, you are keeping your head up during the drill and not getting absorbed in what you are doing, to keep your head up so that you maintain trim, and also so that you maintain situation awareness in case another member of the team has a problem themselves. you are only doing a drill, and need to keep an eye on your team at all times, including when you are doing drills.
4. Shut down the right hand post whilst simultaneously signalling you are manipulating a valve to your team
The signal for manipulating a valve is a clear "Attention!" signal, which consists of a controlled side to side motion with your torch beam. this must be a controlled and relatively slow motion, very different from a "I need assistance URGENT" signal which is a very quick motion with the torch. The signal is continued until the valve is closed. The signal should be given so that all other team mates can see it, and if you are diving in a team of three it is important that you do not get caught in the trap of only signalling to one person.
5. When the post is shut down, breathe down the regulator until it "locks".
This one creates a little discussion, but there are a couple of reasons why we breathe down the regulator. Firstly, it is a check that we have shut down the correct post and indeed are breathing the correct regulator. Most important, it depressurises the regulator. If A post or hose has a small leak, then turning off the post might leave the hose bubbling for some time. The hose needs to be depressurised in order to stop the bubbles. If the bubbles stop after you depressurise the hose, you have found the leak. It will also allow a team member, in a real situation, to reseat the first stage if necessary. finally, it is continual training against panic when you suck on a regulator and nothing happens. It becomes instinctive after several hundred drills - regulator locks, take it out and replace with a backup. this seems obvious, but what you are removing is the initial "Oh shit!" when the regulator locks.
6. Remove the regulator and replace with your backup regulator
The critical word here is "Remove". we do not spit out the regulator and replace it. We remove it with our hand and KEEP it in our hand until we are breathing successfully from another reg. This is so that we do not have to suddenly search for it if the regulator we wish to breathe off fails. It also means we do not have a regulator dangling around. there is a principle in DIR that a regulator is either in our hand, in our mouth, or clipped off. We never leave a regulator hanging as then we do not know exactly where it is. so, in this step, we remove our regulator with our right and then, whilst holding on to that regulator, we place the backup regulator in our mouths.
7. Clip off your primary regulator on the right chest D ring
In the last step, we were left in the position of breathing off our left post, and holding the primary regulator in our right hand. Now, we clip off the regulator onto our right chest D ring. This keeps it neatly stowed away whilst we continue our drills and continues with the ethos that we always know where the regulator is. we clip it to the right chest R ring as opposed to the left because we have a policy of not clipping anything across the body. this again is muscle memory. We do not get into habits of clipping across the body because sooner or later we would clip something across the `long hose and trap it.
8. Open the Right post
So, with the primary clipped off and breathing off the backup, we now reach back and open up the right post, remembering to keep our eyes at all times on our team. We open the post until it is fully open.
9. Unclip the primary regulator and purge it
We now unclip the primary regulator from the right chest D ring and give it a purge. This is to ensure we have turned on the correct regulator and that we are going to get gas from it when we attempt a breathe, which we are shortly to do. Note that we keep hold of the regulator during the purge process and continue to keep hold of it to the next step.
10. Remove the backup regulator from your mouth and replace with the primary regulator
As with the earlier step, we remove the backup rather than spitting it out. We now have the backup regulator in our left hand, and the primary regulator in our right hand, so we replace the primary regulator in our mouth and begin to breathe from it. We can now let go of the backup regulator.
11. Shut down the Isolator whilst simultaneously signalling you are manipulating a valve to your team
We now close down the isolator valve, and as with the earlier steps, we continue to keep our eyes on our team, and clearly signal with the torch in our left hand. We continue to close down the valve until it is fully closed.
12. When the Valve is closed, Re-open the isolator
We do not have a regulator to breathe down with the isolator, so once we have fully closed it, we fully re-open it again. Simple.
13. Move your torch to your right hand
Having finished with the right post and isolator, the next post we are going to deal with is the left post. However, we have an issue here because we hold the torch in a Goodman handle in our left hand. Now this is where some smartarse will say “ahh but I can still manipulate the valve with my left hand”, but what that person would also do is send erratic light signals all over the place as they do so, which could easily be misinterpreted as a problem. So, we don’t do that. What we do is switch the torch to our right hand by sliding it out of the Goodman handle, and grasping the torch in our right hand by the barrel of the light head. This means we can hold the torch and continue to give signals with it, and frees up our left hand to manipulate the left post.
14. Shut down the left hand post whilst simultaneously signalling you are manipulating a valve to your team
Remembering to keep our eyes on our team, and continually giving a clear side to side attention signal, we now reach back with our left hand and shut down the left post until it is fully closed.
15. When the post is closed, purge the backup regulator until it "locks"
Now that the post is closed, we reach to our backup regulator with our left hand, and purge it until it empties. This will depressurise the hose for exactly the reasons we described earlier. Once the regulator has stopped bubbling, we know we have shut down the correct post.
16. Open the left post
We can now open the left hand post. We open the valve fully, and then give the backup regulator a purge to ensure it is functioning correctly again.
17. Move the torch to your left hand
We now slide our left hand back into the Goodman handle of the torch.
18-20 – The flow check
We have essentially finished the valve drill now, but we need to just do a flow check to ensure all posts are back in their correct positions. This is a general DIR policy. Whenever anyone, including yourself, has been manipulating the valves, we do a flow check at the end to ensure all the valves are where they are supposed to be. In the case of the valve drill, all posts should be back in the open position. So we reach back with our right hand and check that the right hand post and the isolator is open. We take the torch in our right hand and check the left hand post is open, and then finally place our left hand back in the Goodman handle and we have completed the flow check.
21. Signal that your drill is complete
As the drill is now complete, we give a signal to the rest of the team that we have completed it and are ready to move on to the next person’s drill, or continue with the dive. There are different ways we do this, but the way our team does this is to give a circle with the torch indicating “OK”. The other team members return the signal. This gives the other team members the information that you are happy, but also you are getting a confirmation from them that they are satisfied that you have put all of your valves back where they are supposed to be. If you had made a mistake and left a post closed at any point, they could intercept you at this point and rectify the situation for you.
Process summary
The basic valve drill involves closing and opening all three posts on a twin set starting with the right post, then the isolator, then the left post.
Process Details
1. Signal to your team you are going to perform a valve drill
2. Wait until your team is in place and then continue
3. Purge Backup regulator
4. Shut down the right hand post whilst simultaneously signalling you are manipulating a valve to your team
5. when the post is shut down, breathe down the regulator until it "locks".
6. Remove the regulator and replace with your backup regulator
7. clip off your primary regulator on the right chest D ring
8. Open the Right post
9. Unclip the primary regulator and purge it
10. Remove the backup regulator from your mouth and replace with the primary regulator
11. Shut down the Isolator whilst simultaneously signalling you are manipulating a valve to your team
12. When the Valve is closed, Re-open the isolator
13. Move your torch to your right hand
14. Shut down the left hand post whilst simultaneously signalling you are manipulating a valve to your team
15. When the post is closed, purge the backup regulator until it "locks"
16. Open the left post
17. Move the torch to your left hand.
18. Check the position of your right hand post
19. Check the position of your isolator
20. Move the torch to your right hand and check the position of your left post
21. Signal that your drill is complete
Looks like a lot of steps, but it really should not take you any more than a minute or so to go through the drill in a nice slow fashion, and I've seen people do it a great deal quicker than this. The trick is to go through the drill slowly and carefully again and again until the movements become muscle memory rather than conscious action. At that point, you can begin to speed up the drill until it becomes both smooth and fast.
Anatomy of the process
Now that we understand the steps we have to take in order to complete the drill, let's look at each step in a little more detail and explain some of the reasoning behind it.
1. Signal to your team you are going to perform a valve drill
OK, so we are diving in a two or a three. We signal to the rest of the team that we are going to do a drill. This means a clear point at all the other team members indicating "You!" and "You", then pointing at your mask indicating "watch me", and then a turning motion with both hands indicating valve drill, hence "You! Watch Me!" "Do a Valve Drill!". this is critical as the rest of the team need to know what is going on so that they are ready if there is a problem. A problem could be you shutting down both posts and leaving yourself out of gas, or something going wrong with your kit. In either situation they need to be ready to step in, and critically, they need to be doing nothing else but watch so that they are not doing any other drills at this time.
2. Wait until your team is in place and then continue
If you are swimming in a line, you need to give your team time to get into a triangle formation all pointing inwards so that they can see you, and see your valves. This is important so that they are in the correct position to donate a long hose if they need to, and so that they can follow your movements on your valves. so have patience and let them get ready before you get going. Once you are all in position, you maintain eye contact with your team. This is done to ensure that firstly, you are keeping your head up during the drill and not getting absorbed in what you are doing, to keep your head up so that you maintain trim, and also so that you maintain situation awareness in case another member of the team has a problem themselves. you are only doing a drill, and need to keep an eye on your team at all times, including when you are doing drills.
4. Shut down the right hand post whilst simultaneously signalling you are manipulating a valve to your team
The signal for manipulating a valve is a clear "Attention!" signal, which consists of a controlled side to side motion with your torch beam. this must be a controlled and relatively slow motion, very different from a "I need assistance URGENT" signal which is a very quick motion with the torch. The signal is continued until the valve is closed. The signal should be given so that all other team mates can see it, and if you are diving in a team of three it is important that you do not get caught in the trap of only signalling to one person.
5. When the post is shut down, breathe down the regulator until it "locks".
This one creates a little discussion, but there are a couple of reasons why we breathe down the regulator. Firstly, it is a check that we have shut down the correct post and indeed are breathing the correct regulator. Most important, it depressurises the regulator. If A post or hose has a small leak, then turning off the post might leave the hose bubbling for some time. The hose needs to be depressurised in order to stop the bubbles. If the bubbles stop after you depressurise the hose, you have found the leak. It will also allow a team member, in a real situation, to reseat the first stage if necessary. finally, it is continual training against panic when you suck on a regulator and nothing happens. It becomes instinctive after several hundred drills - regulator locks, take it out and replace with a backup. this seems obvious, but what you are removing is the initial "Oh shit!" when the regulator locks.
6. Remove the regulator and replace with your backup regulator
The critical word here is "Remove". we do not spit out the regulator and replace it. We remove it with our hand and KEEP it in our hand until we are breathing successfully from another reg. This is so that we do not have to suddenly search for it if the regulator we wish to breathe off fails. It also means we do not have a regulator dangling around. there is a principle in DIR that a regulator is either in our hand, in our mouth, or clipped off. We never leave a regulator hanging as then we do not know exactly where it is. so, in this step, we remove our regulator with our right and then, whilst holding on to that regulator, we place the backup regulator in our mouths.
7. Clip off your primary regulator on the right chest D ring
In the last step, we were left in the position of breathing off our left post, and holding the primary regulator in our right hand. Now, we clip off the regulator onto our right chest D ring. This keeps it neatly stowed away whilst we continue our drills and continues with the ethos that we always know where the regulator is. we clip it to the right chest R ring as opposed to the left because we have a policy of not clipping anything across the body. this again is muscle memory. We do not get into habits of clipping across the body because sooner or later we would clip something across the `long hose and trap it.
8. Open the Right post
So, with the primary clipped off and breathing off the backup, we now reach back and open up the right post, remembering to keep our eyes at all times on our team. We open the post until it is fully open.
9. Unclip the primary regulator and purge it
We now unclip the primary regulator from the right chest D ring and give it a purge. This is to ensure we have turned on the correct regulator and that we are going to get gas from it when we attempt a breathe, which we are shortly to do. Note that we keep hold of the regulator during the purge process and continue to keep hold of it to the next step.
10. Remove the backup regulator from your mouth and replace with the primary regulator
As with the earlier step, we remove the backup rather than spitting it out. We now have the backup regulator in our left hand, and the primary regulator in our right hand, so we replace the primary regulator in our mouth and begin to breathe from it. We can now let go of the backup regulator.
11. Shut down the Isolator whilst simultaneously signalling you are manipulating a valve to your team
We now close down the isolator valve, and as with the earlier steps, we continue to keep our eyes on our team, and clearly signal with the torch in our left hand. We continue to close down the valve until it is fully closed.
12. When the Valve is closed, Re-open the isolator
We do not have a regulator to breathe down with the isolator, so once we have fully closed it, we fully re-open it again. Simple.
13. Move your torch to your right hand
Having finished with the right post and isolator, the next post we are going to deal with is the left post. However, we have an issue here because we hold the torch in a Goodman handle in our left hand. Now this is where some smartarse will say “ahh but I can still manipulate the valve with my left hand”, but what that person would also do is send erratic light signals all over the place as they do so, which could easily be misinterpreted as a problem. So, we don’t do that. What we do is switch the torch to our right hand by sliding it out of the Goodman handle, and grasping the torch in our right hand by the barrel of the light head. This means we can hold the torch and continue to give signals with it, and frees up our left hand to manipulate the left post.
14. Shut down the left hand post whilst simultaneously signalling you are manipulating a valve to your team
Remembering to keep our eyes on our team, and continually giving a clear side to side attention signal, we now reach back with our left hand and shut down the left post until it is fully closed.
15. When the post is closed, purge the backup regulator until it "locks"
Now that the post is closed, we reach to our backup regulator with our left hand, and purge it until it empties. This will depressurise the hose for exactly the reasons we described earlier. Once the regulator has stopped bubbling, we know we have shut down the correct post.
16. Open the left post
We can now open the left hand post. We open the valve fully, and then give the backup regulator a purge to ensure it is functioning correctly again.
17. Move the torch to your left hand
We now slide our left hand back into the Goodman handle of the torch.
18-20 – The flow check
We have essentially finished the valve drill now, but we need to just do a flow check to ensure all posts are back in their correct positions. This is a general DIR policy. Whenever anyone, including yourself, has been manipulating the valves, we do a flow check at the end to ensure all the valves are where they are supposed to be. In the case of the valve drill, all posts should be back in the open position. So we reach back with our right hand and check that the right hand post and the isolator is open. We take the torch in our right hand and check the left hand post is open, and then finally place our left hand back in the Goodman handle and we have completed the flow check.
21. Signal that your drill is complete
As the drill is now complete, we give a signal to the rest of the team that we have completed it and are ready to move on to the next person’s drill, or continue with the dive. There are different ways we do this, but the way our team does this is to give a circle with the torch indicating “OK”. The other team members return the signal. This gives the other team members the information that you are happy, but also you are getting a confirmation from them that they are satisfied that you have put all of your valves back where they are supposed to be. If you had made a mistake and left a post closed at any point, they could intercept you at this point and rectify the situation for you.
DIR Minimum Gas - Explained (by Team Foxturd)
Minimum Gas
The DIR concept of “minimum gas” is the unbreakable rule by which we plan our dives. Minimum gas represents the minimum amount of gas carried by each diver that will allow the diver to get themselves, and another diver, to the next available gas source. For a short shallow dive, this might mean a direct ascent to the surface. For a longer dive with mandatory decompression stops, this might mean the ascent to a depth where it becomes appropriate to switch to another gas. Minimum gas is an absolute. It is never violated during the bottom portion of the dive, and once minimum gas is reached, the only option is to call the dive and ascend immediately.
Gas Rules
This is how we plan our gas to be used. Let’s say our minimum gas is 70 Bar in our twinset, and we start the dive with 220 bar. That means we have 150 bar of usable gas. With that 150 bar, we then apply a gas rule. That rule might be thirds (when the dive MUST return to a starting point), halves (when it would be useful for the diver to return to the start point but not essential) or all useable gas (where the diver can just ascend from wherever they are and be picked up). The “All useable gas” rule is often applied in UK waters where the boat can just come and get us, but we might apply halves if the skipper wants us to return to a shotline. The beauty of the gas rules is that if we get back to our starting point early, and ahead of minimum gas, we can just recalculate our halves, or thirds, and go off again.
Calculating Minimum Gas
The fundamantal principle. At all times, a DIR diver enough gas to get themselves, and a team mate, to the next available gas source.
OK, so in order to know how much gas we have available for the dive, and in order to know our safety factor, we have to be able to calculate minimum gas. I’m going to run through two examples, a thirty metre dive where we can ascend directly to the surface, and a 45 metre dive, where we have to ascend to 21M to do a gas switch
30 Metre Dive
To calculate min deco, we make several assumptions.
• Firstly, we assume an ascent rate of 9M per minute to 50% of the depth, then 3 Metres per minute after that.
• Secondly, we assume a SAC rate of 30 Litres per minute for both divers. This might seem high to some people. But, in an incident, SAC rate can hit 100. Even if it then settles down, it’s going to average out significantly higher than your normal rate
• We assume one minute at the bottom sorting out whatever has gone wrong and getting moving
So, here we are at thirty metres, and all hell breaks loose so two divers have to ascend directly to the surface on one diver’s backgas.
50% of 30m = 15 metres
So, from the bottom
1 Minute resolving Issue
2 Minutes to get from 30M to 15M (plan on 9m/min but most people achieve around 7m/min)
1 Minute to get from 15M to 12M
1 Minute to get from 12M to 9M
1 Minute to get from 9M to 6M
1 Minute to get from 6M to 3M
1 Minute to get from 3M to the surface
This means a 8 minute ascent time.
Now we need to know the average depth. For the dive above, I would call the average depth 10 Metres or 2 Bar
8 minutes of Gas for 2 divers = 16 minutes of Gas required
Depth consumption Rate = 2 Bar X 30 Litres = 60 Litres Per minute
16 X 60 = 960 Litres of Gas Required
Therefore minimum gas for this dive would be 960 litres of gas, or 40 bar in a set of twin 12 litre cylinders.
So, on a 30 metre dive, with both divers using twin 12s, we know we need to leave the bottom before we hit 40 bar to ensure that if there is a total loss of gas for one diver, we can safely and slowly ascend to the surface. This might be far more conservative than other measures due to the slow ascent rate, but it is very comforting to know we can ascend at this rate and still know we have enough gas.
If we have a 220 bar fill in the twinset, and are going to be picked up by the boat, this gives us 160 bar to use during the dive which is nice.
Some people might find the maths a little baffling, but others might just see it immediately. Once you run a few of them through your head you can do it simply enough. We would do this before we hit the water if it was a known depth, or at the bottom of the shotline if it was different than expected.
Now, these figures are always the same, so you could work out the min gas required for each depth, or write them on a slate. However, this defeats the true strength of the calculation, and it is strongly encouraged that DIR divers learn to do this in their heads. Here’s the reason. Let’s say you reach the seabed, and the depth is shallower or deeper than you planned, you can just recalculate minimum gas on the spot and make the most of the gas you have with you without risking safety. That last factor is the real winner for me, and the calculation is simple enough after a while.
Let’s take the calculation a little deeper, shall we say 45 metres?
45 Metre Dive
On this dive, we are at 45M and we are carrying a stage of 50%. Remember that Minimum gas is supposed to get you and another dive to the next available gas source, which in this case is 21M where we would switch to the 50%.
We use the same SAC of 30 Litres Per minute.
80% of the ATAs (or 75% depth) in this case is 34 metres, but for simplicity we deal in multiples of 3 metres, so we will call it 33 metres.
This, then is the ascent profile
1 minute at 45 metres resolving issue
2 minutes to get from 45 to 33 (its more than 9 metres so has to be 2 minutes travel)(upto 80% = 9mtr/min)
1 minute to get from 33 to 27 (80% to 21m = 6mtr/min)
1 minute to get from 27 to 21
1 minute to allow for gas switch
This gives us an 6 minute ascent to the gas switch
Now we need to know the average depth. For the dive above, I would call the average depth 33 Metres or 4.3 Bar.
The calculation, then…
6 minutes of Gas for 2 divers = 12 minutes of Gas required
Depth consumption Rate = 4.3 Bar X 30 Litres = 129 Litres Per minute
12 X 129 = 1548 Litres of Gas Required.
In a set of twin 12s this would equate to 65 bar. Again, we will round this up to be 70 bar. Assuming a 220 bar fill, and again using the gas rule of all available gas, this means we have 150 bar of gas to play with before we have to leave the bottom.
So that’s minimum gas a la DIR.
Remember that you “could” always get up a lot faster than this, but why not plan for a nice controlled, slow ascent, rather than planning for a race up to the surface.
In addition, the numbers here are exact, but in the case of a different bottom depth, it would be advisable to use easier numbers e.g. 4.5 instead of 4.3 (working this through min gas would still be 70bar rounded up).
Finally, as the depths increase, the time spent at 1.5x your normal SAC during the ascent is not realistic and also becomes penalising and so those DIR divers doing Tech 2+ depths use a different average SAC rate than 1.5x
Finally, just a reminder of the Golden Rule
At all times during a dive, we carry enough gas to get ourselves, and a buddy or team mate, to the next available gas source. This rule is never violated.
The DIR concept of “minimum gas” is the unbreakable rule by which we plan our dives. Minimum gas represents the minimum amount of gas carried by each diver that will allow the diver to get themselves, and another diver, to the next available gas source. For a short shallow dive, this might mean a direct ascent to the surface. For a longer dive with mandatory decompression stops, this might mean the ascent to a depth where it becomes appropriate to switch to another gas. Minimum gas is an absolute. It is never violated during the bottom portion of the dive, and once minimum gas is reached, the only option is to call the dive and ascend immediately.
Gas Rules
This is how we plan our gas to be used. Let’s say our minimum gas is 70 Bar in our twinset, and we start the dive with 220 bar. That means we have 150 bar of usable gas. With that 150 bar, we then apply a gas rule. That rule might be thirds (when the dive MUST return to a starting point), halves (when it would be useful for the diver to return to the start point but not essential) or all useable gas (where the diver can just ascend from wherever they are and be picked up). The “All useable gas” rule is often applied in UK waters where the boat can just come and get us, but we might apply halves if the skipper wants us to return to a shotline. The beauty of the gas rules is that if we get back to our starting point early, and ahead of minimum gas, we can just recalculate our halves, or thirds, and go off again.
Calculating Minimum Gas
The fundamantal principle. At all times, a DIR diver enough gas to get themselves, and a team mate, to the next available gas source.
OK, so in order to know how much gas we have available for the dive, and in order to know our safety factor, we have to be able to calculate minimum gas. I’m going to run through two examples, a thirty metre dive where we can ascend directly to the surface, and a 45 metre dive, where we have to ascend to 21M to do a gas switch
30 Metre Dive
To calculate min deco, we make several assumptions.
• Firstly, we assume an ascent rate of 9M per minute to 50% of the depth, then 3 Metres per minute after that.
• Secondly, we assume a SAC rate of 30 Litres per minute for both divers. This might seem high to some people. But, in an incident, SAC rate can hit 100. Even if it then settles down, it’s going to average out significantly higher than your normal rate
• We assume one minute at the bottom sorting out whatever has gone wrong and getting moving
So, here we are at thirty metres, and all hell breaks loose so two divers have to ascend directly to the surface on one diver’s backgas.
50% of 30m = 15 metres
So, from the bottom
1 Minute resolving Issue
2 Minutes to get from 30M to 15M (plan on 9m/min but most people achieve around 7m/min)
1 Minute to get from 15M to 12M
1 Minute to get from 12M to 9M
1 Minute to get from 9M to 6M
1 Minute to get from 6M to 3M
1 Minute to get from 3M to the surface
This means a 8 minute ascent time.
Now we need to know the average depth. For the dive above, I would call the average depth 10 Metres or 2 Bar
8 minutes of Gas for 2 divers = 16 minutes of Gas required
Depth consumption Rate = 2 Bar X 30 Litres = 60 Litres Per minute
16 X 60 = 960 Litres of Gas Required
Therefore minimum gas for this dive would be 960 litres of gas, or 40 bar in a set of twin 12 litre cylinders.
So, on a 30 metre dive, with both divers using twin 12s, we know we need to leave the bottom before we hit 40 bar to ensure that if there is a total loss of gas for one diver, we can safely and slowly ascend to the surface. This might be far more conservative than other measures due to the slow ascent rate, but it is very comforting to know we can ascend at this rate and still know we have enough gas.
If we have a 220 bar fill in the twinset, and are going to be picked up by the boat, this gives us 160 bar to use during the dive which is nice.
Some people might find the maths a little baffling, but others might just see it immediately. Once you run a few of them through your head you can do it simply enough. We would do this before we hit the water if it was a known depth, or at the bottom of the shotline if it was different than expected.
Now, these figures are always the same, so you could work out the min gas required for each depth, or write them on a slate. However, this defeats the true strength of the calculation, and it is strongly encouraged that DIR divers learn to do this in their heads. Here’s the reason. Let’s say you reach the seabed, and the depth is shallower or deeper than you planned, you can just recalculate minimum gas on the spot and make the most of the gas you have with you without risking safety. That last factor is the real winner for me, and the calculation is simple enough after a while.
Let’s take the calculation a little deeper, shall we say 45 metres?
45 Metre Dive
On this dive, we are at 45M and we are carrying a stage of 50%. Remember that Minimum gas is supposed to get you and another dive to the next available gas source, which in this case is 21M where we would switch to the 50%.
We use the same SAC of 30 Litres Per minute.
80% of the ATAs (or 75% depth) in this case is 34 metres, but for simplicity we deal in multiples of 3 metres, so we will call it 33 metres.
This, then is the ascent profile
1 minute at 45 metres resolving issue
2 minutes to get from 45 to 33 (its more than 9 metres so has to be 2 minutes travel)(upto 80% = 9mtr/min)
1 minute to get from 33 to 27 (80% to 21m = 6mtr/min)
1 minute to get from 27 to 21
1 minute to allow for gas switch
This gives us an 6 minute ascent to the gas switch
Now we need to know the average depth. For the dive above, I would call the average depth 33 Metres or 4.3 Bar.
The calculation, then…
6 minutes of Gas for 2 divers = 12 minutes of Gas required
Depth consumption Rate = 4.3 Bar X 30 Litres = 129 Litres Per minute
12 X 129 = 1548 Litres of Gas Required.
In a set of twin 12s this would equate to 65 bar. Again, we will round this up to be 70 bar. Assuming a 220 bar fill, and again using the gas rule of all available gas, this means we have 150 bar of gas to play with before we have to leave the bottom.
So that’s minimum gas a la DIR.
Remember that you “could” always get up a lot faster than this, but why not plan for a nice controlled, slow ascent, rather than planning for a race up to the surface.
In addition, the numbers here are exact, but in the case of a different bottom depth, it would be advisable to use easier numbers e.g. 4.5 instead of 4.3 (working this through min gas would still be 70bar rounded up).
Finally, as the depths increase, the time spent at 1.5x your normal SAC during the ascent is not realistic and also becomes penalising and so those DIR divers doing Tech 2+ depths use a different average SAC rate than 1.5x
Finally, just a reminder of the Golden Rule
At all times during a dive, we carry enough gas to get ourselves, and a buddy or team mate, to the next available gas source. This rule is never violated.
Ratio Deco at the Tech1 Level (by Team Foxturd)
Firstly, a few caveats. I have put some thought into all of this so please don't skip them. I expect they will be obvious to everyone on YD, but perhaps not to the person who googles Ratio Deco and stumbles across this post.
1. This post does not represent Ratio Deco as taught by GUE, FifthD or indeed any other agency. It is my interpretation of what I have been taught. Thus, any errors are my own.
2. Ratio Deco usually forms only a small part of a larger course and requires a rounded grasp of specific skills that allow Ratio Deco to be utilised safely. Thus, before using Ratio Deco I can only recommend you seek such training. Please do not dive the profiles suggested in this post without undertaking such training. You could end up hurt or dead.
3. Ratio Deco works in conjuction with a specific set of variables. There are no rules, only guidelines. Use them at your peril.
A few myths dealt with
It's mystic sorcery and "secret" information - well it aint anymore if it ever was
It's complicated - keep reading, it's so simple it's dissapointing once you learn it!
It requires lots of training - The skills required to handle RD do take time to learn. RD itself takes about 15 minutes on Tech1
OK. Now that's out of the way, are you all sitting comfortably, good, then I'll begin....
Has anyone read AndrewG's article on Ratio Deco? The man may be a diving God, and may no more about decompression than most people on the planet, but by God he's a terrible writer. Or perhaps I am simply insulting him and it's written in a such a fashion to enocurage people to take courses and have the concepts clearly explained. The only documentation on RD I have been able to find on the web has been obfuscated by crepuscular logic and an involute style which, frankly, gets on my tits. I thought it might be useful to post some information about ratio Deco that demystifies it, and allows for a more informed debate and discussion on the topic.
So, what is Ratio Deco.
Garf's Definition - the Wordy one
Ratio Deco is defined as being a set of rules that allow an individual or team to calculate the amount of mandatory deco and ascent rates based on the average depth they have been at and the length of time they have been at the bottom.
Garf's defintion - The easy one
If we know how deep we are and how long we've been there we can work out the deco on the way up in our heads without the need of a computer.
"Ratio" refers to the fact that, for a given depth, there is a ratio between the length of time a diver spends on the bottom portion of a dive and the amount of decompression they will have to do on the way to the surface. "Deco" refers to the fact that this process is managing the ascent portion of the dive, including all deep stops, ascent rates, and shallow stops.
Other definitions
"Bottom Time" - The time that passes from the time we arrive at the bottom to the time we leave the bottom. Notice does not include the descent portion of the dive.
"Bottom Gas" - 21/35 or 18/45 Only. The two are interchangeable and the decompression required stays the same. Handy huh
"Decompression Gas" - 50% Only.
The Pre-requisites
In order to make Ratio Deco work for us, there are a number of things we need to be able to do, and a few things we must have with us.
Firstly, we need to be able to control our rate of ascent. I don't mean stop ourselves from rocketing to the surface, although that's a handy skill. I mean we need to be able to change our rate of ascent on demand. For Tech1 level diving, we need to be able to ascent at a constant 3 metres per minute where necessary, 6 metres per minute where necessary and 9 metres per minute where necessary. If we cannot do any of that, don't go near Ratio Deco.
Secondly, we need to have with us standard gases. The ratio deco I am going to explain in this post works when we use either 21/35 or 18/45 as backgas and 50% as deco gas. And that's it. Mess up the standard gases, and it all goes to ratshit. With some confidence and experience behind you, you could alter the deco to compensate, but I am a long way from that in my diving and for the sake of simplicity and safety let's just say that the standard gases are the rule. There are other standard backgases, and other standard decompression mixes, but we are not interested in them at the Tech1 level.
Thirdly, we need to understand something of the limitations. During the course of this post, I am going to explain that Ratio Deco is anot a rigid set of rules, but needs to be adjusted based on variables such as depth. For the sake of this post, I am going to say that the guidelines I give out are good to 48 metres and 40 minutes. Deeper or longer than that and the ratio we are going to use starts to become a little wooly, and needs to be adjusted until we reach the next "set point", which I shall explain in a moment.
Concept One : The Set Point: Calculating Decompression Required.
forget about Rebreathers, this is a different type of set point. The set point is the starting point for calculating Ratio Deco. At the tech1 level, we use 45Metres as the set point. As you increase in knowledge, you may use 66M as a set point and so on.
So, for Tech1, we use 45M. At this set point, we assume that there is a 1:1 Ratio between bottom time and decompression. That means for every minute we spend on the bottom, we spend a minute decompressing. There, wasn't that nice and simple. Minute on the Wreck, minute going up. easy.
Now, there are other Ratios. for example at 66 metres, the gases all change and the ratio is 2:1. for every minute on the wreck we need to do 2 minutes deco. Now I'm not going to get into that here becuase, frankly, I'm not trained to do it.
Let's go back to our 1:1 ratio at 45M. We do a 30 minute dive to 45M (average depth), we need to do 30 minutes decompression. Nice. However, what if our average depth was greater or less than 45M. Well for every 3 metres (or part) shallower than the plan, we take 5 minutes off the deco. for every 3 metres (or part) we add 5 minutes.
So, calculating the amount of decompression we need to do is very simple indeed. Look at the average depth and the time, and compare to 45 Metres.
Example 1: 38 metres for 40 minutes - We're 2 lots of three away from 45 (rounded down) so it must be 10 minutes less than 40 - 30 minutes.
Example 2: 47 metres for 25 minutes - We're above the 45M setpoint by part of a three so it must be 5 minutes more than 25 - 30 minutes.
So, you can see that it's very easy indeed to calculate the decompression in the 30 to 48 metre range. It get's a little more complicated if you go deeper as you are moving between the 1:1 Ratio at 45 metres and the 2:1 ratio at 66 metres, so the question arises of what do you do in the middle. That is a question I sort of know the answer to, but am not qualified to post, and it's outside the scope of what I want to cover in this post anyway. Let's stay at 48M or below to keep things nice and simple.
Portions of the Dive.
Let's go back to our 30 minute dive to 45 Metres. We now know that we have 30 minutes decompression to do on the way up, but how do we do it. Where do we do our stops, and how long should each stop be.
Well, the areas of the dive can be broken down as follows;
Bottom to 80% of Average ATAS = Lower Portion of Ascent.
80% of ATAs to 21M = Deep Stops
21 metres = Gas switch
21M - 9M = Intermediate Stops
6M - surface = Shallow Stops
Or, just for Janos, a pretty chart...
Now, let's deal with each portion of the ascent in turn.
Bottom Portion of Ascent
At this point, we are still ongassing. So, there's no reason to hang about with slow ascent rates. We use 9 metres per minute as it's quick enough to get us out of dodge, but slow enough so it can be brought to a stop comfortably. We want to get up to 80% of our ATAS at 9 metres per minute because if we do it any slower then we are going to bugger up our decompression by ongassing too much. It is critical at this point not to hang about. Once the decision is made to leave the bottom, we leave.
We need to get up to 80% of our ATAS before anything changes. Why 80%. Becuase it's around this area that we stop ongassing and start off gassing. Now, as with everything in DIR, it's not perfect for all oaccassions, but it's about the best standard you can apply to all situations, which is really what the entire concept of DIR is all about. so 80% of our ATAS. How the hell do we work that out. Sounds complicated. Here's the trick...
Let's say we're our average depth was 45 metres. convert that to ATAS =5.5. divide by ten = 0.55. Mutiply by 2 = 1.1. Take that off the depth in metres. 45 Metres - 1.1 ATAS = 34 metres. So, 80% of the ATAS when we have been diving to 45 Metres is 34 metres.
Let's do another example. We've been to 42 metres. Thats 5.2 ATAS. Multiply by 2 = 10.4. Call it 11. Take that off the depth in metres. 42 - 1.1 ATA (11m) = 31 metres.
Repeat that above excercise a few times and you'll find you can do it in a heartbeat without thinking about it, and it's the most complicated bit of maths we have to do in the whole excercise.
Now, just to make things a tad more complicated, we always round to the nearest three, becuase then it's a bloody doddle to do 3 metres per minute up to 21M. So if our 80% is at 34M, we'd actually go up to 33. If our 80% was actually 31 metres then we'd stop at 30M. See how that works?
So, taking our 30 minute dive to 45 metres. We leave the bottom after 30 minutes and we ascend at a rate of 9 metres per minute until we hit 33 metres. This probably takes us about 75 seconds.
Deep Stops Portion of Ascent
OK, so we hit 33 metres and we are now in the deep stops portion of the ascent. At the Tech1 level, this is simple. We do 1 minute stops every three metres. Looking at this another way, we can just do 15 seconds move, 15 seconds stop, which looking at it yet another way, could be done as a 6 metre per minute ascent, which is actually what we do. So all we have to do at this point in the dive is slow down from 9 metres per minute to 6 metres per minute, and then ascend at that rate until we hit 21 metres.
Now, this is an area where I could go on for ever more. The deep stops change if you go beyond Tech1 levels, and all of a sudden the maths gets a little more complicated with longer stops and changing ascent rates, but that's for another day. On our nice, simple 30 minute dive to 45 metres, all we have to do is slow down the ascent rate until we hit 21 metres.
21 Metres - the Gas Switch and first intermediate stop
21 metres is where the work begins. Here we have to switch the team from their back gas onto the decompression gas of 50%. We also need to put up a bag, and work out how much deco we have to do.
Let's get going. The gas switch. The procedure for that is another post, and I never would have believed this until trained to do it, but switching the entire team from backgas to decompression gas takes about 10 seconds. Backgas regulators are clipped off. Now, the roles come into play. Typically one person sends up a bag from 21 whilst another person is running the deco.
The first intermediate stop depth is 21 metres, however we stop at 21M for at least 3 minutes regardless of how much decompression is actually required. why do we do this. We do this to open the Oxygen Window. Now, I've read and know at least 4 different versions of what the words "Oxygen Window" actually mean, but all of them seem to agree that it's not a bad idea to spend at least 2-3 minutes at the depth where you switch to your decompression gas containing a higher partial pressure of O2. Obviously, several compartments are still ongassing, and also you have a limited gas supply, so you don;t want to stay there forever, but 3 minutes as a minimum for Ratio Deco as I am explaining it.
Shaping the Decompression Curve - Intermediate Stops.
Ahh, Howard it putting up the bag, I'd better work out what deco we are going to do before he finishes or he'll only take the piss. Well, we did 30 minutes at 45 metres. That means we have 30 minutes of Decompression to do. so where do we do it
Well, we need to do half our decompression in the intermediate stops, and half in the shallow stops.
Let's take our dive, 30 minutes at 45 metres. We have 30 minutes of decompression to do. that means we have to do 15 minutes at 21-9 metres (see table 2) and 15 minutes at 6-0 metres (see table 2).
Now, our intermediate stops are alwasy the same. They are
21M
18M
15M
12M
9M
That means we have five stops to do. If 50% of our deco is therefore divisible by 5, it's simple. We have 15 minutes to do in the intermediate stops. So we would do the following
21M - 3 minutes
18M - 3 minutes
15M - 3 minutes
12M - 3 minutes
9M - 3 minutes
Now how bloody simple is that.
There is an endless debate about whether you should do a linear curve as I have described above, or whether you should minimise the stops in the middle and load the start and end. This would mean you maximise the deco from the partial pressure of 50% and then start to push the gradient, and ignore the stuff in the middle. This becomes more apparant when the deco is NOT divisible by 5, becuase then the divers have a choice about where to do the stops.
Let's look at a few examples of that.
Let's say we have 18 minutes to do in the intermediate portion. I'd probably do
21M - 4 minutes
18M - 4 minutes
15M - 2 minutes
12M - 4 minutes
9M - 4 minutes
but we could also do
21M - 4 minutes
18M - 3 minutes
15M - 3 minutes
12M - 4 minutes
9M - 4 minutes
There is no right or wrong, and different people do different things. It becomes far more regimented at the Tech2 and Tech3 levels, but at the Tech1 level, you will get away with pretty much anything. Howard has put the bag up now. we'll wait until the clock hits three minutes at 21M and then move through the intermediate stops. We'll actually move a little faster so we are moving for 30 seconds and stablisiing for thirty seconds. Up we go to 6 metres.
Shaping the Decompression Curve - Shallow Stops.
Well, here we are at 6 metres. We had 30 minutes of decompression to do, 15 of which we did in the intermediate stops, and 15 of which we need to do here. We have a few options here. We could just do 15 minutes at 6 and then ascend over 5 minutes. If the surface conditions did not allow this we could do 18 mins and then a 2 minute ascent. Team foxturd take the best of both world, and would do the 15 minutes at 6 and then attempt a 5 minute ascent. But we're in no rush to get to the surface.
That was easy, wasn't it.
The simple example
45 metres. 30 minutes.
We thumb the dive and leave the bottom. We need to get to 80% of the ATAS. Let's see, thats 5.5 X 2 taken away from 45. That's means 34 metres. Let's call it 33.
We go up to 33 at 9 metres per minute. It takes just over a minute. We slow down to 23 metres per minute and it takes us another 4 minutes to get to 21 Metres. We started at 45 metres so its the 1: 1 ratio. We did 30 mins so we have 30 mins deco to do, 15 in the intermediate stops and 15 in the shallows.
We then switch gas and bag up.
15 minutes is divisible by 5, which makes the deco easy...
21M - 3 minutes
18 M - 3 Minutes
15M - 3 Minutes
12 - 3 Minutes
9M - 3 Minutes
Now we are at 6 metres. We have 15 minutes to do so we do them and then ascend as slowly as possible
The complicated example.
Here we are on the Salsette. We have been swimming around and over things so the average depth is actually 42 metres. We have been on the bottom for 28 minutes. Gareth hits minimum gas, so we thumb the dive. We leave the bottom immediately on thumbing the dive.
Up we go at 9 metres per minute. 80% of the ATAS from 42 metres is 5.2 *2 = 10.4 taken away from 42 = 11 metres, so lets call it 31 metres. Actually, we call it 30. It takes us a minute and a bit to get there.
At 30 we slow down to 3 metres per minute. It takes us a further 3 minutes to get to 21 Metres. During which time I'll have probably worked out the deco.
Now we gas switch and put a bag up. We do 3 minutes at 21M.
We did 42 metres for 28 minutes. thats 3 metres less than 45 so take off 5 minutes. We have 23 minutes deco to do. Sod that, let's do 24
Half of 24 is 12, divided by 5 is not possible so let's do the following
21 M = 3 Minutes
18 Metres = 2 Minutes
15 Metres = 2 Minutes
12 Metres = 2 Minutes
9 Metres = 3 Minutes
Up we go through the intermediate stops.
Now we are at 6 metres. We have 12 minutes to do
Let's keep things simple. 12 minutes at 6 and then ascend as slowly as possible.
Dive Over.
Now wasn't that painless?
Comparisons with Dive Models
The nearest model to ratio deco for the sake of comparison is gradient factors of 30/85
Taking our two dives,
the 45 metre /30 min dive would give us a runtime of about 66 mins (with a 3 minute ascent from 6m), as compared to a runtime of 63 mins from decoplanner.
the 42 metre / 28 min dive would give us a runtime of about 59 mins (with a 3 minute ascent from 6M), as compared to a runtime of 53 mins from decoplanner.
It will be closer or further away depending on the depths and times. Ratio deco is not perfect, it suits some dives better than others.
Summary
DIR is not about a perfect configuration, or a perfect set of standards. It's about providing a kit configuration and set of standards that can be applied everywhere. It may be a good fit in some situations, and a poorer fit in others, but there is so much advantage in having the standard that DIR divers who think through all the standards just have to accept this.
Ratio Deco, like everything else in DIR, does not provide the perfect option for all scenarios. However, it does provide an option that fits all scenarios to a greater or lesser degree. Learning where these degrees are is all part of the education process. If we dived to 54 metres, I probably wouldn't be happy with 1:1, but would start padding it out.
Whilst on the subject of padding, the question may arise where one person in the team wants to do more deco. It doesn't matter why. The most conservative person always wins. Of someone wants to extend the stops, that's what we do, no discussion, no arguments.
One interesting point is that if you always round up the deco to the next ten minutes, it all becomes ridiculously easy. Lets say we have 30 minutes deco to do. That's 15 in the intermediate stops and 15 in the shallows. I get to 18 metres and signal 3. If we follow the rule of always rounding up the deco to the next ten minutes then the team know from that one signal exactly how much deco I am planning on doing at each stop, and the total amount of deco we have to do. However, that is making the assumption that you don't mind doing a few extra minutes deco.
We do not really have to worry about carrying enough deco gas becuase using this form of ratio deo and using twin 12s means we will not be able to get into the position of not having enough deco gas unless we lose our AL80 deco bottle. If that happens, Ratio Deco also allows for a lost deco gas. We can just double the stops and deco out on the back gas. At the Tech1 level, it just works in terms of gas logistics.
Now, just on a closing note, for the love of God don't go out and do this without training in all the other elements I have mentioned.
The DIR Head to Toe Check (by Team Foxturd)
The
DIR Head to toe check is something that gets taught to you and drilled in to you
in every training course. At the fundies level, it can seem overkill, as it
takes a couple of minutes, and some of the items checked just seem ridiculous.
At the Tech1 level and above, the reasons for the checks become more obvious,
and indeed can be suitably demonstrated by the instructor failing the piece of
kit if he/she sees you missing a piece of the check. You have already checked a
great deal of this when actually putting the kit on, but this is a check
witnessed by the whole team, when you are about to hit or go under the water.
the purpose of the check is to ensure that everything required to get you and
the team back out of the water safely is attached properly, and working
properly, so that you don't find out when you need it that it is not there. Lots
of divers do a predive check, but many people do many different versions of it.
If you are diving with someone new, how do you know what they will check etc. We
do this the same way within our team every time, because the time you don't is
the time you miss something.
Anyway, someone asked me to document it for them, so I just thought it might make an interesting excercise to write and expand it into an article. . The check, as the name suggests, begins at the head and ends at the toes. The precise order seems to vary depending on who is doing it, but the principle of moving down the body is sound, as it prompts you to remember things you may otherwise have forgotten. The check is done either on the boat in the sea, or in the water inland. It's worth noting at this point, that this head to toe forms part of the GUE EDGE pre dive checks (winner of the dumbest name in world history award). Anyway, on we go.
The check is done as a team. Each person is checking their own kit, but looking to the others to confirm they have actually checked theirs, and in some cases, doing the check for them. Each team member will have a role assigned to them for the dive. This will dictate their position in the water - diver 1 will lead, and in a three man team diver 3 will bring up the rear. This team element also manifests itself during kitting up, and during the head to toe check. Although each person will check their own kit, Diver 1 will check diver 2 where necessary, diver 2 will check diver 3 and diver 3 will check diver 1. This way everyone understands from the start who they will be checking, and nobody gets missed. It's all about making the checks flow smoothly. It is the same ethos that we use when doing a gas switch. 1 switches first, then 2 then 3.
Hood
Is it on. An obvious one, but I'm sure I'm not the only diver to have seen people jump in without a hood and practically leap back out of the water onto the boat to get it.
Mask
Is it on, and ready (demisted). Also, check your team's masks - are they trapping the hood and likely to flood once you descend. 20M per minute is not the time to find out your mask is flooding as it just becomes a stress factor and ups the breathing rate, and yet we see it all the time - divers having to stop on the ascent to sort things out. Whilst this might not be a big deal to them, we have a constant descent rate because we do not include the descent as part of bottom time for deco calculations - so stopping to sort something out for two minutes at 35 metres can bugger things up.
Valves - Flow Check
Reach behind you and check that all your valves are in the appropriate position - fully open for us. I've been guilty of leaving the isolator closed in the dark and hopefully distant past, descending with 200 bar, and surfacing with 200 bar. Oops. If you have deco bottles or stages, check that the valves are are again in the appropriate position - for us this means charged and then switched off. finally, check the suit inflation bottle if you have one. Again 20M per minute down to 50M becomes a real pain the arse if your argon bottle is switched off. We also perform another flow check at the bottom of a shotline in case anyone has rolled off a post against the line on the way down.
Regulators
Breathe Both regaulators in the water, so dip your head, breathe from the primary, do a switch to the necklaced reg and check it breathes. If your 2nd stages diaphram has become unseated, the reg will breathe lovely on the surface, and breathe water underwater. Not nice. Best to find out now than when you have to dinate gas to someone and find you have nothing left to breathe off.
Torch
Is your primary torch now deployed and in your head. Is it switched on and working. Are your backup torches in position. If not, get out of the water and sort it out. Trust me on this one
Modified S Drill
Take the second stage out of your mouth and hold it in your hand. Dip your head and undo the long hose. Undo it from the canister light and check it is free all the way back to the first stage. Hold it up in the air so your team mates can see it - they are the interested ones because they are the ones You are checking to make sure you can donate gas freely at any point, a critical piece of the configuration, yet it does get missed. We missed this once on Tech1 and spent a portion of the dive having to do mask to mask gas donations because the hoses were becoming trapped. Restow the hose carefully when you have finished. I was coaching a diver a few weeks ago and saw the same thing when he was kitting up and the inevitable out of gas I threw at him went predictably pie-shaped. I suspect he won't do it again.
Bubble check.
Whilst we're looking at the valves, let's check them for bubbles. Turn around onto your back and let your teammates look at your valves / manifold. Then let them check your suit inflation bottle and hoses, inflation valves, SPGs, deco bottles, stages. Diver 1 checks diver 2, diver 2 checks diver 3, diver 3 checks diver 1. This is a theme that goes all the way through DIR, each person has a role, and each person knows who they should be keeping an eye on / checking, so it happens smoothly and in an understood order. This takes practice.
Suit Dump Valve
Is it in the appropriate position. I forgot this on one of my fundies dives, leaving it mostly closed with air in the suit. It was a very uncomfortable dive, and the ascent was ludicrously messy as I now had a large bubble of gas to manage on the way up. Most divers I know just open it and leave it there, but the important thing is that you check it and it is in the position you want it to be in.
Suit Inflate Valve
Is the hose connected properly, can it be pulled off. Does it iactually inflate the suit properly without water ingressing. Suit squeeze - not nice
Wing Inflate
Is the hose connected properly or entangled. Can the low pressure hose be pulled off. Does the wing inflate.
Wing Dumps
Does the corrugated hose dump work effectively. Does the kidney dump work effectively. I missed this one on a Tech1 dive and found to my horror on the ascent that the string was not there. Kerslake denied cutting it, but who knows. You are checking to make sure you can actually reach it - you haven't got anything in the way, and that it functions correctly
Instruments
Have you remembered to put on the instruments on your arms? hold your arms up and let your team see - they might be counting on you to call the deco. GLOC's deco is shaky at the best of times, but when we arrived at 52 metres on the moldavia with nothing on his arms and showed us...well, you can imagine how the conversation went on the boat. An easy one to forget.
Weight system
How many times have you seen people jump in without weights. Easy at the start of the dive, especially in a twinset, but I bet its a sickening feeling realising as that twinset gets lighter when you realise that "something" that you were sure you had forgotten is what would have kept you from hitting the surface early.
Knife
Can you reach it, with both hands. Is it on the appropriate place on yoru harness so that your team mates know where to get it if they need it.
Pockets
We tell each other at this point what we are carrying in our pockets. This is pretty easy for us, as we are all carrying the same things, in the same pockets, but this is when someone goes "bugger, I forgot my SMB" when they tap their pockets to make sure they are appropriately full. This is also the time for people to deal with anything poking out of pockets for a team mate and tidy it away.
Deco Bottles
If you have clipped off your deco bottles to your hip d ring, have a team mate check to make sure that your main SPG coming off your left post is not clipped off THROUGH one of the hoses, making deployment of the deco regulator a job of either hvaing to thred it through, or removing the spg and then reattaching it. This was my biggest one on Tech1, kept doing this, and its amazing how much stress it adds when you can't pull the hose free. Whilst we are looking at each other's deco bottles, are the second stages stowed neatly away on all the bottles, and can we read the MOd markings clearly on the bottle for when we authorise a gas switch later in the dive.
Fins
Are we wearing them today?
Anyway, someone asked me to document it for them, so I just thought it might make an interesting excercise to write and expand it into an article. . The check, as the name suggests, begins at the head and ends at the toes. The precise order seems to vary depending on who is doing it, but the principle of moving down the body is sound, as it prompts you to remember things you may otherwise have forgotten. The check is done either on the boat in the sea, or in the water inland. It's worth noting at this point, that this head to toe forms part of the GUE EDGE pre dive checks (winner of the dumbest name in world history award). Anyway, on we go.
The check is done as a team. Each person is checking their own kit, but looking to the others to confirm they have actually checked theirs, and in some cases, doing the check for them. Each team member will have a role assigned to them for the dive. This will dictate their position in the water - diver 1 will lead, and in a three man team diver 3 will bring up the rear. This team element also manifests itself during kitting up, and during the head to toe check. Although each person will check their own kit, Diver 1 will check diver 2 where necessary, diver 2 will check diver 3 and diver 3 will check diver 1. This way everyone understands from the start who they will be checking, and nobody gets missed. It's all about making the checks flow smoothly. It is the same ethos that we use when doing a gas switch. 1 switches first, then 2 then 3.
Hood
Is it on. An obvious one, but I'm sure I'm not the only diver to have seen people jump in without a hood and practically leap back out of the water onto the boat to get it.
Mask
Is it on, and ready (demisted). Also, check your team's masks - are they trapping the hood and likely to flood once you descend. 20M per minute is not the time to find out your mask is flooding as it just becomes a stress factor and ups the breathing rate, and yet we see it all the time - divers having to stop on the ascent to sort things out. Whilst this might not be a big deal to them, we have a constant descent rate because we do not include the descent as part of bottom time for deco calculations - so stopping to sort something out for two minutes at 35 metres can bugger things up.
Valves - Flow Check
Reach behind you and check that all your valves are in the appropriate position - fully open for us. I've been guilty of leaving the isolator closed in the dark and hopefully distant past, descending with 200 bar, and surfacing with 200 bar. Oops. If you have deco bottles or stages, check that the valves are are again in the appropriate position - for us this means charged and then switched off. finally, check the suit inflation bottle if you have one. Again 20M per minute down to 50M becomes a real pain the arse if your argon bottle is switched off. We also perform another flow check at the bottom of a shotline in case anyone has rolled off a post against the line on the way down.
Regulators
Breathe Both regaulators in the water, so dip your head, breathe from the primary, do a switch to the necklaced reg and check it breathes. If your 2nd stages diaphram has become unseated, the reg will breathe lovely on the surface, and breathe water underwater. Not nice. Best to find out now than when you have to dinate gas to someone and find you have nothing left to breathe off.
Torch
Is your primary torch now deployed and in your head. Is it switched on and working. Are your backup torches in position. If not, get out of the water and sort it out. Trust me on this one
Modified S Drill
Take the second stage out of your mouth and hold it in your hand. Dip your head and undo the long hose. Undo it from the canister light and check it is free all the way back to the first stage. Hold it up in the air so your team mates can see it - they are the interested ones because they are the ones You are checking to make sure you can donate gas freely at any point, a critical piece of the configuration, yet it does get missed. We missed this once on Tech1 and spent a portion of the dive having to do mask to mask gas donations because the hoses were becoming trapped. Restow the hose carefully when you have finished. I was coaching a diver a few weeks ago and saw the same thing when he was kitting up and the inevitable out of gas I threw at him went predictably pie-shaped. I suspect he won't do it again.
Bubble check.
Whilst we're looking at the valves, let's check them for bubbles. Turn around onto your back and let your teammates look at your valves / manifold. Then let them check your suit inflation bottle and hoses, inflation valves, SPGs, deco bottles, stages. Diver 1 checks diver 2, diver 2 checks diver 3, diver 3 checks diver 1. This is a theme that goes all the way through DIR, each person has a role, and each person knows who they should be keeping an eye on / checking, so it happens smoothly and in an understood order. This takes practice.
Suit Dump Valve
Is it in the appropriate position. I forgot this on one of my fundies dives, leaving it mostly closed with air in the suit. It was a very uncomfortable dive, and the ascent was ludicrously messy as I now had a large bubble of gas to manage on the way up. Most divers I know just open it and leave it there, but the important thing is that you check it and it is in the position you want it to be in.
Suit Inflate Valve
Is the hose connected properly, can it be pulled off. Does it iactually inflate the suit properly without water ingressing. Suit squeeze - not nice
Wing Inflate
Is the hose connected properly or entangled. Can the low pressure hose be pulled off. Does the wing inflate.
Wing Dumps
Does the corrugated hose dump work effectively. Does the kidney dump work effectively. I missed this one on a Tech1 dive and found to my horror on the ascent that the string was not there. Kerslake denied cutting it, but who knows. You are checking to make sure you can actually reach it - you haven't got anything in the way, and that it functions correctly
Instruments
Have you remembered to put on the instruments on your arms? hold your arms up and let your team see - they might be counting on you to call the deco. GLOC's deco is shaky at the best of times, but when we arrived at 52 metres on the moldavia with nothing on his arms and showed us...well, you can imagine how the conversation went on the boat. An easy one to forget.
Weight system
How many times have you seen people jump in without weights. Easy at the start of the dive, especially in a twinset, but I bet its a sickening feeling realising as that twinset gets lighter when you realise that "something" that you were sure you had forgotten is what would have kept you from hitting the surface early.
Knife
Can you reach it, with both hands. Is it on the appropriate place on yoru harness so that your team mates know where to get it if they need it.
Pockets
We tell each other at this point what we are carrying in our pockets. This is pretty easy for us, as we are all carrying the same things, in the same pockets, but this is when someone goes "bugger, I forgot my SMB" when they tap their pockets to make sure they are appropriately full. This is also the time for people to deal with anything poking out of pockets for a team mate and tidy it away.
Deco Bottles
If you have clipped off your deco bottles to your hip d ring, have a team mate check to make sure that your main SPG coming off your left post is not clipped off THROUGH one of the hoses, making deployment of the deco regulator a job of either hvaing to thred it through, or removing the spg and then reattaching it. This was my biggest one on Tech1, kept doing this, and its amazing how much stress it adds when you can't pull the hose free. Whilst we are looking at each other's deco bottles, are the second stages stowed neatly away on all the bottles, and can we read the MOd markings clearly on the bottle for when we authorise a gas switch later in the dive.
Fins
Are we wearing them today?
DIR Rules. Explained (by Team Foxturd)
Rule 1 - "DO NOT DIVE WITH UNSAFE DIVERS"
It’s the first rule, arguably the most important, and the one that has raised the most emotions in the past. It has been erroneously translated by dumb-ass DIR and non-DIR divers as “Don’t dive with people outside your team” or even “Don’t dive with people from another agency”, and by some real dipsticks “Only dive with DIR divers”.
This is an error.
The rule does not mean don’t dive with a particular type of person. It means don’t dive with someone who is unsafe. So what is an unsafe diver.? Forget the agency, training or background. Your best friend and GUE team mate can be an unsafe diver as much as anyone else. An unsafe diver is someone who is not physically or psychologically prepared, in your opinion, to safely conduct the dive you have planned. Maybe their kit looks cobbled together because they rushed. Maybe something on their kit looks like it needs maintenance. Perhaps they are so focussed on themselves they are not taking an active team role in preparing for the dive. Perhaps they haven’t analysed their gas, or conducted a proper pre dive briefing with you. Perhaps you are not on the save wavelength regarding the dive plan, or the decompression strategy. Perhaps they are using kit they are clearly not comfortable with, or trying out new kit on an inappropriate dive. There might be a million and one things, but I’d come back to someone who is not prepared, in your opinion. To safely conduct the dive.. Someone will raise so I’ll pre-empt it – the rule has also been described as “Don’t dive with strokes”. A stroke, in this context, is an unsafe diver, regardless of background or training. Rule 1 then, Do not dive with unsafe divers.
Rule 2 – “DO NOT LISTEN TO UNSAFE DIVERS”
As a general rule, if you have decided someone is acting in an unsafe manner, you probably don't want to listen to any arguments they might have. Again, this does not mean “don’t listen (or speak to, as someone once suggested) to non-DIR divers. It means don’t take advice from people you shouldn’t’. I have been guilty of this so many times. I hear a diver, using a different configuration, or different signals, or kit, or whatever, and I think “that sounds cool, I’ll incorporate that into my diving”. I’ve just forgotten the point of DIR, which is that the strength is in standardisation, and the moment someone starts moving away from that standard, the system begins to fray around the edges. I can jump in the water with any DIR diver and know exactly how their kit is supposed to be setup, and how intend to conduct the dive. Until someone starts mucking about with the standard. Another take on the “do not listen” rule – You think your best mate is unsafe today because they haven’t analysed their gas – there’s no current sticker on it (IE one that says they analysed it TODAY). They tell you it’s fine because they did it last week. If you listen to that, you’ve broken rule 2.
Rule 3 -NOTHING UNDERWATER IS WORTH DYING FOR
Surely this is obvious to everyone. Yet we keep hearing about people who stayed just a little bit too long. Or went a little bit too deep. Etc. George Irvine came out with a lot of vitriolic nonsense, but one of the things he said which rings true to me is that no-one gets any smarter underwater. If you’ve made a plan on the surface, stick to it in the water, as you made it for a reason. If you happen to stumble across the treasure of the Sierra Madre but you have reached minimum gas, tough shit. Come back tomorrow. I can personally attest that it’s far more pleasant being at home wishing you were diving, than being diving wishing you were at home.
Rule 4 – ALWAYS ANALYSE YOUR GAS (BEFORE EVERY DIVE)
Logic would suggest that this would be the least emotive rule. Surely everyone would agree this is a sensible idea. But every now and again, someone dies for the lack of adhering to it. A couple of years ago, I tested my twinset on the boat as I prepared for my 40 metre dive, and found to my consternation that I had 200 bar of pure Oxygen in my twinset. How my body would have reacted to a partial pressure of Oxygen of 5.0 I cannot precisely determine, but I think it’s far to say the dive would have been both brief and somewhat eventful. Another diver I know blacked out whilst sitting on the side of a rib as he prepared to roll off the side into the sea. He can be thankful to an unnamed and unknown gas filler for the low price he had been charged for a very expensive fill, and thankful to his body’s swift reaction to the 100% helium in his twinset for probably saving his life. Stuff like this happens. Most of the time, it gets caught in time. When it doesn’t, the unfortunate result is that we tend to read about it. Gas accidents sicken me, because their results can be so easily fatal, and yet so easily avoided. Analyse your gas before every dive, including after air tops in the morning. Do not make any assumptions based on what people are telling you. Analyse anything you might potentially have to breathe. Mark your cylinders with the current date, and check your team mates to make sure they have done the same. If they haven’t, see rules 1 and 2. If the shit hits the fan you might have to breathe what's in their cylinders, so check those stickers before you hit the water.
Rule 5 - DON'T DIVE A RE-BREATHER UNLESS YOU NEED IT
DIR’s stance on rebreathers is fairly simple. There is a balance of risk and need. DIR Divers believe that rebreathers are, generally speaking, more dangerous than Open Circuit. However, there are certain dives where the risks of open circuit outweigh the risks of closed circuit. Where gas logistics become ludicrous – extremely long exposure cave exploration, or very deep wreck diving, then there is an argument that a rebreather is the tool of choice. I have to be honest, if I wrote more on this rule I’d be making it up. I don’t do these types of dives, so I don’t really relate to this rule.
Rule 6 – ALWAYS LOOK COOL / FABULOUS.
T hat seems a bit silly doesn’t it? Everything I’ve written above is designed to help safety, so what’s this bollox about looking cool?Just a joke? Maybe. But think about it a bit and all of a sudden you start to see something in it.Let’s just assume for a moment that the rule does not mean “Only wear black”. Let’s also assume that it doesn’t mean “Only buy Halcyon”. On a side note, I don’t know of a single DIR diver that only uses Halcyon equipment. Anyway, I digress. DIR and Non-Divers that make the assumption that this is what the rule actually means are missing the point.
Let’s imagine you are on a boat. Your potential buddy’s equipment looks messy, or poorly maintained. Maybe the hose routing looks all untidy. They are clearly in breach of rule 6. What’s important is not that their configuration is not neat, or their equipment knackered. What’s important is that they have rushed their setup, or have been failing to keep up to date with maintenance. Refer to rule 1. Let’s assume your buddy’s cylinders have 15 different stickers on them. Bong. Rule 6 violation. But again the important thing is that you might not be able to identify a current gas test sticker or, god forbid, misread the maximum operating depth. Refer to Rule 1. Now you’re in the water. Your buddy is dropping in and out of trim. They are waving their arms about. Bong. Rule 6 violation. They are not looking cool. Equally, if you have your head switched on, you now know that they are uncomfortable for some reason. Don’t ignore it. Find out why.
Rule 6 is not about looking cool for the sake of cool. It’s about looking in control, prepared, calm. In short, it’s about demonstrating you are a safe diver.
Those are the rules. There is one small addition I might as well make to this post. Something we call “Option 1”. Option one is very simple indeed.
Option 1 Any diver can call any dive. At any time.
Before or during the dive. No debate. No questioning. No argument. The dive is over. Why someone calls a dive is irrelevant. They have decided they want to be out of the water, or don’t want to get into it. Diving is supposed to be fun. So respect that decision. Would you really want to be in the water with someone who doesn’t. If someone tries to convince you to dive when you don’t feel comfortable, please refer to Rule 1.
It’s the first rule, arguably the most important, and the one that has raised the most emotions in the past. It has been erroneously translated by dumb-ass DIR and non-DIR divers as “Don’t dive with people outside your team” or even “Don’t dive with people from another agency”, and by some real dipsticks “Only dive with DIR divers”.
This is an error.
The rule does not mean don’t dive with a particular type of person. It means don’t dive with someone who is unsafe. So what is an unsafe diver.? Forget the agency, training or background. Your best friend and GUE team mate can be an unsafe diver as much as anyone else. An unsafe diver is someone who is not physically or psychologically prepared, in your opinion, to safely conduct the dive you have planned. Maybe their kit looks cobbled together because they rushed. Maybe something on their kit looks like it needs maintenance. Perhaps they are so focussed on themselves they are not taking an active team role in preparing for the dive. Perhaps they haven’t analysed their gas, or conducted a proper pre dive briefing with you. Perhaps you are not on the save wavelength regarding the dive plan, or the decompression strategy. Perhaps they are using kit they are clearly not comfortable with, or trying out new kit on an inappropriate dive. There might be a million and one things, but I’d come back to someone who is not prepared, in your opinion. To safely conduct the dive.. Someone will raise so I’ll pre-empt it – the rule has also been described as “Don’t dive with strokes”. A stroke, in this context, is an unsafe diver, regardless of background or training. Rule 1 then, Do not dive with unsafe divers.
Rule 2 – “DO NOT LISTEN TO UNSAFE DIVERS”
As a general rule, if you have decided someone is acting in an unsafe manner, you probably don't want to listen to any arguments they might have. Again, this does not mean “don’t listen (or speak to, as someone once suggested) to non-DIR divers. It means don’t take advice from people you shouldn’t’. I have been guilty of this so many times. I hear a diver, using a different configuration, or different signals, or kit, or whatever, and I think “that sounds cool, I’ll incorporate that into my diving”. I’ve just forgotten the point of DIR, which is that the strength is in standardisation, and the moment someone starts moving away from that standard, the system begins to fray around the edges. I can jump in the water with any DIR diver and know exactly how their kit is supposed to be setup, and how intend to conduct the dive. Until someone starts mucking about with the standard. Another take on the “do not listen” rule – You think your best mate is unsafe today because they haven’t analysed their gas – there’s no current sticker on it (IE one that says they analysed it TODAY). They tell you it’s fine because they did it last week. If you listen to that, you’ve broken rule 2.
Rule 3 -NOTHING UNDERWATER IS WORTH DYING FOR
Surely this is obvious to everyone. Yet we keep hearing about people who stayed just a little bit too long. Or went a little bit too deep. Etc. George Irvine came out with a lot of vitriolic nonsense, but one of the things he said which rings true to me is that no-one gets any smarter underwater. If you’ve made a plan on the surface, stick to it in the water, as you made it for a reason. If you happen to stumble across the treasure of the Sierra Madre but you have reached minimum gas, tough shit. Come back tomorrow. I can personally attest that it’s far more pleasant being at home wishing you were diving, than being diving wishing you were at home.
Rule 4 – ALWAYS ANALYSE YOUR GAS (BEFORE EVERY DIVE)
Logic would suggest that this would be the least emotive rule. Surely everyone would agree this is a sensible idea. But every now and again, someone dies for the lack of adhering to it. A couple of years ago, I tested my twinset on the boat as I prepared for my 40 metre dive, and found to my consternation that I had 200 bar of pure Oxygen in my twinset. How my body would have reacted to a partial pressure of Oxygen of 5.0 I cannot precisely determine, but I think it’s far to say the dive would have been both brief and somewhat eventful. Another diver I know blacked out whilst sitting on the side of a rib as he prepared to roll off the side into the sea. He can be thankful to an unnamed and unknown gas filler for the low price he had been charged for a very expensive fill, and thankful to his body’s swift reaction to the 100% helium in his twinset for probably saving his life. Stuff like this happens. Most of the time, it gets caught in time. When it doesn’t, the unfortunate result is that we tend to read about it. Gas accidents sicken me, because their results can be so easily fatal, and yet so easily avoided. Analyse your gas before every dive, including after air tops in the morning. Do not make any assumptions based on what people are telling you. Analyse anything you might potentially have to breathe. Mark your cylinders with the current date, and check your team mates to make sure they have done the same. If they haven’t, see rules 1 and 2. If the shit hits the fan you might have to breathe what's in their cylinders, so check those stickers before you hit the water.
Rule 5 - DON'T DIVE A RE-BREATHER UNLESS YOU NEED IT
DIR’s stance on rebreathers is fairly simple. There is a balance of risk and need. DIR Divers believe that rebreathers are, generally speaking, more dangerous than Open Circuit. However, there are certain dives where the risks of open circuit outweigh the risks of closed circuit. Where gas logistics become ludicrous – extremely long exposure cave exploration, or very deep wreck diving, then there is an argument that a rebreather is the tool of choice. I have to be honest, if I wrote more on this rule I’d be making it up. I don’t do these types of dives, so I don’t really relate to this rule.
Rule 6 – ALWAYS LOOK COOL / FABULOUS.
T hat seems a bit silly doesn’t it? Everything I’ve written above is designed to help safety, so what’s this bollox about looking cool?Just a joke? Maybe. But think about it a bit and all of a sudden you start to see something in it.Let’s just assume for a moment that the rule does not mean “Only wear black”. Let’s also assume that it doesn’t mean “Only buy Halcyon”. On a side note, I don’t know of a single DIR diver that only uses Halcyon equipment. Anyway, I digress. DIR and Non-Divers that make the assumption that this is what the rule actually means are missing the point.
Let’s imagine you are on a boat. Your potential buddy’s equipment looks messy, or poorly maintained. Maybe the hose routing looks all untidy. They are clearly in breach of rule 6. What’s important is not that their configuration is not neat, or their equipment knackered. What’s important is that they have rushed their setup, or have been failing to keep up to date with maintenance. Refer to rule 1. Let’s assume your buddy’s cylinders have 15 different stickers on them. Bong. Rule 6 violation. But again the important thing is that you might not be able to identify a current gas test sticker or, god forbid, misread the maximum operating depth. Refer to Rule 1. Now you’re in the water. Your buddy is dropping in and out of trim. They are waving their arms about. Bong. Rule 6 violation. They are not looking cool. Equally, if you have your head switched on, you now know that they are uncomfortable for some reason. Don’t ignore it. Find out why.
Rule 6 is not about looking cool for the sake of cool. It’s about looking in control, prepared, calm. In short, it’s about demonstrating you are a safe diver.
Those are the rules. There is one small addition I might as well make to this post. Something we call “Option 1”. Option one is very simple indeed.
Option 1 Any diver can call any dive. At any time.
Before or during the dive. No debate. No questioning. No argument. The dive is over. Why someone calls a dive is irrelevant. They have decided they want to be out of the water, or don’t want to get into it. Diving is supposed to be fun. So respect that decision. Would you really want to be in the water with someone who doesn’t. If someone tries to convince you to dive when you don’t feel comfortable, please refer to Rule 1.
5 Ocak 2012 Perşembe
2 Ocak 2012 Pazartesi
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