diver 85
Contributor
Have done it several times in a 2.5mm & 120 steel...what's the problem and why an empty BC??......
No steel tanks with wetsuits?
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Have done it several times in a 2.5mm & 120 steel...what's the problem and why an empty BC??......
SparticleBrane
Contributor
Just going with worst case scenario.
No point in flaming me, just tossing things out into the mix.
No point in flaming me, just tossing things out into the mix.
When I got certified this was all part of basic Scuba training. We didn’t have 130 cu ft tanks, but all our tanks were steel.
We not only had to thread water and be able to remove and put on our rig on the surface, we swam many laps on the surface with it. Oh …and we didn’t have to worry about having air in the BC. We didn’t have a BC or any surface flotation aid during basic Scuba training. You learn real quickly to never be over-weighted.
Removing your gear on the surface should be easy, especially if you have a quick release waist and shoulder strap. I don’t understand why some new rigs don’t have a quick release on the shoulder.
And to simulate worst case condition, we swam laps with simulated equipment lost:
Only one fin, then no fins, then we could use our fins but no snorkel, and then we could keep the snorkel but no mask, etc. I learned that if I am going to loose anything, the mask is the least important. For surface swim with no BC a snorkel will save you from having to ditch your tank.
It doesn’t seem that much fun to have the strong equipment dependence that many divers have now a day, never mind safety.
IMHO any tank selection should work, with your complete gear set, so that when you are out of air you should be neutral (or maybe even just a bit positive) at the surface with no buoyancy aids.
Hi Max, always good to see a fellow Ontario boy around.
The issue really isn't how tough it is to tread water on the surface with a dead BC and a steel tank. Well, not totally anyway. It would be tougher than it should be, but if we consider the gas in the tank is gone/low, and that the diver was truly weighted correctly in the first place, you wouldn't be seriously negative.
Of course as you know from your OW class that you would ideally ditch some weight when in distress at the surface, but with a steel tank, depending on the diver, suit, etc etc, you may not have had any to ditch. That's a problem for me.
The real issue as it pertains to steel tanks and wet suits is actually at it's worse when you are at depth, and when you're diving a heavy wetsuit. (5mm or 7mm).
Assuming again we're always speaking of divers that are properly weighted, what you have here vs. someone diving a lighter wetsuit, is that you need a lot of weight to compress the neoprene to get you started, but that weight is now part of a non-ditchable steel tank, which becomes an albatros around your neck once the neo of your wetsuit compresses at depth. You are at that point undeniably way over weight. If you have a wing failure there, it may very well be depending on the diver and the situation an impossibility to swim upwards to the surface.
Interestingly, again assuming a properly weighted diver, that the problem is LESS of an issue with lighter wet-suits, as you don't have as much neo to compress, and you don't have that inherent huge buoyancy loss as with thicker wet-suits.
The problem is it is a little tough to know 'how much' buoyancy loss you have with a particular wetsuit at depth, you just know it this problem gets worse with depth as well as when the thickness of the wetsuit is increased, so those of us that understand this just use a simple rule of thumb to not wear wetsuits with steel tanks. It's not always true and you can find exceptions if you want to.
If you really want to find out, get to depth with your chosen gear, dump you gas in your wing and see how you fare. May as well make it a full tank to ensure you have your worst case scenario.
Hope that is clear as mud for you.
This deal with the old-timers and no buoyancy device is one of two things. Either one walked around rediculously negative on the bottom and found it real tough to stay on the surface, or with the guys that cared a bit more than that, they were forced to be as properly weighted as they could. There really was no inbetween or other way around it.
Then they got smart and started using bleach jugs and stuff
BC's today make it very easy to remain neutrally buoyant at all points in the dive, and this simply wasn't possible before they existed. The problem with BC's is that people can now way over-weight themselves and it is not necessarily readily apparent to some of them, until they lose the ability to use the BC due to failure.
The WKPP info is correct. This has nothing to do with different environments, and everything to do with basic buoyancy concepts.
regards
SparticleBrane
Contributor
Once again, Steve explains the situation much more eloquently than I ever could have.
Gilldiver
Contributor
My basic problem with the whole dead BC thing is, How do you get a 100% dead BC?
The only way I can see it happening is if you tear the BC inflator hose, it comes unscrewed from the BC, or it gets broken off.
The old rubber corrugated hoses were easier to tear then the new ones. But I don't ever remember seeing one get torn. The new hoses are much tougher and almost tare/ puncture proof.
If the hose comes unscrewed, you take your gear off and put it back on or get your buddy to do it for you.
I have seen a hose broken off, but only on a boat or on land due to handling problems. I have never seen a hose broken off underwater. Now, I could see it happening if you were scootering fast and it got hooked on part of an overhead, be it a cave or wreck. Since I don't have a scooter and don't do caves, there is no problem here.
The last thing that can happen is a puncture in the BC, Been there - Done that. Sure you loose some air but it is a slow leak and by changing your position in the water to keep the puncture at the lowest level you can, it can be dealt with easily.
If you are thousands of feet back into a cave, with twin 130's there may be a reason to worry about the whole steel/wetsuit issue, but for the vast majority of divers it is a non-issue.
The only way I can see it happening is if you tear the BC inflator hose, it comes unscrewed from the BC, or it gets broken off.
The old rubber corrugated hoses were easier to tear then the new ones. But I don't ever remember seeing one get torn. The new hoses are much tougher and almost tare/ puncture proof.
If the hose comes unscrewed, you take your gear off and put it back on or get your buddy to do it for you.
I have seen a hose broken off, but only on a boat or on land due to handling problems. I have never seen a hose broken off underwater. Now, I could see it happening if you were scootering fast and it got hooked on part of an overhead, be it a cave or wreck. Since I don't have a scooter and don't do caves, there is no problem here.
The last thing that can happen is a puncture in the BC, Been there - Done that. Sure you loose some air but it is a slow leak and by changing your position in the water to keep the puncture at the lowest level you can, it can be dealt with easily.
If you are thousands of feet back into a cave, with twin 130's there may be a reason to worry about the whole steel/wetsuit issue, but for the vast majority of divers it is a non-issue.
Yes. Not a huge problem IF your tank still has sufficient air left in it (as it should). If not, you have a problem!
I routinely dove an HP120 wet with a single wing. On some of my deep dives I've often thought about the issue of wing redundancy, and may head in that direction in the future (or carry a lift bag) since I dive solo.
For most of my diving above 100 ft I don't worry about it since I often swim up with a largely deflated wing anyway. After all, I didn't use a BCD at all during the first 29 years of my diving "career."
This deal with the old-timers and no buoyancy device is one of two things. Either one walked around rediculously negative on the bottom and found it real tough to stay on the surface, or with the guys that cared a bit more than that, they were forced to be as properly weighted as they could. There really was no inbetween or other way around it.
Then they got smart and started using bleach jugs and stuff
regards
We never walked on the bottom, except when I dove a brass hard hat
, but that was mostly last spring.I grew up diving in the Caribbean so being properly weighted was easy (I only wore a shorty wet suit). The weight change for a single 72 tank is less than 5.4 lbs. Therefore, being close to neutral the whole dive without a BC is not too difficult.
What some divers use to do to deal with the neoprene compression and buoyancy loss at depth was to weight themselves for the expected diving depth. You just swim down and at depth you were neutral (this was before anyone ever thought of a safety stop). But, in some dives were I knew I was exiting in the same area where I entered I have done a similar technique, by leaving weight behind and picking them up on the way up.
I dont know about bleach jugs, but I have been thinking about using a couple of PVC rigid 2 short pipes to get 5 lbs of constant positive lift at the beginning of a dive. As I consume the air out of the tank I would pull a plug to flood one pipe (then flood the other one for a shallow safety stop). Using a couple of small rigid ballast cylinders I think I could do a dive without messing with the volume change of air in the bladder and I wouldnt have to touch the inflator.
My impression of this issue/question has been:
- it seems the assumption is that all weight is non-ditchable (other than ditching equipment)
- It seems the issue is the ability to maintain enough neutral buoyancy in an overhead environment...so if a BC fails, you need to not crash in to the ceiling from ditching weight...you need to be able to get out of the cave or wreck. In an open water environment, we can always bail out to the surface.
- Steel and AL tanks mean diving with about the same amount of weight; it is just a question of if some of the weight is incorporated in to the tank + lead or more lead carried to compensate for a buoyant tank
- If the recommendation is to not use steel tanks, then the recommendation should also be to not use non-ditchable ballast weight pockets in BCs...since it doesn't mention this it seems the recommendation is not geared to recreational BC configurations and open water diving.
- So, it is possible to use an AL tank and still have the risk since the diver is carrying extra lead to make up for the positive buoyancy of the AL tank....and if that lead is not ditchable then there could still be a problem.
- It seems a diver who is way overweighted will have the issue regardless of the type of tank they are carrying....if the wing goes, then they sink.
- In the WKPP scenario, the diver still has an air supply, so an OW diver should still be able to swim up a negative rig. If we add an out of air situation, then it seems taking a position on this issue also involves taking a position on the positive buoyant ascent (i.e. ditching some weight at depth if you cannot get to the surface in time via a swimming ascent). I would much rather use a buoyancy of my dry suit to make the ascent, but a wetsuit diver would have to swim it up being negative...if they are also OOA or too negative to swim it up, then the buoyant ascent comes in.
My conclusion is that using an steel tank should be fine for OW and a wetsuit as long as there is enough ditchable weight to be able to make an ascent at max depth with a full tank and an empty BC and no air supply (like faulty first stage)....like a bunch of things go wrong at the beginning of the dive right after the descent.
Thank you Steve R and Rob 9000. When reading this thread from the start it was obvious that people were missing the point.
Steel tanks are not all significantly heavier. Some, like the generic steel 72 and the X7-100 are only a few pounds more negative than for example an AL80.
In my opinion, if you have problems treading water on the surface in just your doubles (you can drop the stage bottles deco bottles, reels, lights, etc.) you are badly overweighted and doing the pillsbury doughboy imitation with your drysuit is not the correct solution.
The issue at depth in a wet suit is wet suit compression where the compressed suit can leave you so excessively negative with large steel doubles that you cannot swim to the surface in the event your BC fails. In this case you also cannot neccesarily unload the deco tanks, etc. nor can you drop weight if you are in an over head environment and/or have a deco obligation that prevents you from having the luxury of ascending all the way to the surface in a positively bouyant condition. This is a concern as the wet suit will regain the bouyancy it lost as you near the surface, but you cannot regain lost weight and will then be too positive to maintain a deco stop. With a dry suit is is not much of a problem as the suit can be over inflated (compared to normal) to gain the bouyancy needed to get everything to the surface in a controlled manner without skipping deco stops. But obviously the situation only applies to technical diving where you do not have the recreational option of ditching weight at depth (although a technical diver still can still configure themselves so as to be able to ditch weight at the surface, which can be very handy after you surface if the boat is not there to pick you up, as long as the method used is reliable enough to ensure that unintended weight loss will not occur at depth.)
So on the one hand, yes care needs to be taken to ensure that you take into account the potential for wet suit compression (especially with a heavy 7mm wet suit) when diving large doubles to ensure that you can swim them up or have a backup bpuyancy system (dry suit, redundant wing or a lift bag with an easily controllable dump). But on the other hand, care also needs to be paid to the overall configuration.
Personally, it totally escapes me why some technical divers go everywhere in a stainless steel back plate when they are already badly over weighted and an aluminum backplate would be a better choice that would leave them about 4 lbs less negative. Apparently it is just cooler to have a SS plate rather than aluminum, even if it potentially kills you.
In some cases an SS plate makes sense if you would have to carry weight anyway, since in deco diving, dumping weight is not an option anyway. But then that same diver will change locations where less exposure protection is needed and invariably ends up being very negative with the SS plate and a large and very negative when full set of doubles.
Rather than adhere to a general rule like no steel tanks with a wet suit, it makes more sense to look at things from a systems perspective and assess whether your entire configuration makes sense and make adaptations and changes when the situation dictates - ie switching to an AL rather than SS plate in warm water or perhaps diving double AL80's rather than a more negative set of steel tanks in warm water if the dive profile allows.
In general though getting a total wing failure is rare. I have had the rear dump fail open and have had to ascend vertically to keep the air trapped in the wing (the main reason wings do not have shoulder mounted dump valves is that you do not want a failure prone valve that high on the wing where it would prevent air trapping). A large hole high in the wing could be problematic, but is unlikely unless you are crashing around inside a wreck and generally using less than ideal technique.
In any case, whenever possible a recreatonal diver shouldl weight themselves so that they are neutral at their 15 ft safety stop with no air in the BC and aboput 500 psi in the tank. This will ensure that they are not overweighted. The overweighting problem comes from a tendency for instructors to address technique issues, like the diver un knowingly finning at the surface, by adding more weight - and then of course advising the new diver to track the weight required in their log so they can continue to be over weighted. Another cause is weighting for a new wet suit that will becomes less bouyant after several dives that cause some permant crushing of some of the neoprene bubbles. The moral of the story is to repeat the bouyancy check at 15 ft whenever you get the chance and if you find yourself sinking with no air in the bc and only 500 psi in the tank, you are now to heavy and need to lose a pound or two of weight.
Steel tanks are not all significantly heavier. Some, like the generic steel 72 and the X7-100 are only a few pounds more negative than for example an AL80.
In my opinion, if you have problems treading water on the surface in just your doubles (you can drop the stage bottles deco bottles, reels, lights, etc.) you are badly overweighted and doing the pillsbury doughboy imitation with your drysuit is not the correct solution.
The issue at depth in a wet suit is wet suit compression where the compressed suit can leave you so excessively negative with large steel doubles that you cannot swim to the surface in the event your BC fails. In this case you also cannot neccesarily unload the deco tanks, etc. nor can you drop weight if you are in an over head environment and/or have a deco obligation that prevents you from having the luxury of ascending all the way to the surface in a positively bouyant condition. This is a concern as the wet suit will regain the bouyancy it lost as you near the surface, but you cannot regain lost weight and will then be too positive to maintain a deco stop. With a dry suit is is not much of a problem as the suit can be over inflated (compared to normal) to gain the bouyancy needed to get everything to the surface in a controlled manner without skipping deco stops. But obviously the situation only applies to technical diving where you do not have the recreational option of ditching weight at depth (although a technical diver still can still configure themselves so as to be able to ditch weight at the surface, which can be very handy after you surface if the boat is not there to pick you up, as long as the method used is reliable enough to ensure that unintended weight loss will not occur at depth.)
So on the one hand, yes care needs to be taken to ensure that you take into account the potential for wet suit compression (especially with a heavy 7mm wet suit) when diving large doubles to ensure that you can swim them up or have a backup bpuyancy system (dry suit, redundant wing or a lift bag with an easily controllable dump). But on the other hand, care also needs to be paid to the overall configuration.
Personally, it totally escapes me why some technical divers go everywhere in a stainless steel back plate when they are already badly over weighted and an aluminum backplate would be a better choice that would leave them about 4 lbs less negative. Apparently it is just cooler to have a SS plate rather than aluminum, even if it potentially kills you.
In some cases an SS plate makes sense if you would have to carry weight anyway, since in deco diving, dumping weight is not an option anyway. But then that same diver will change locations where less exposure protection is needed and invariably ends up being very negative with the SS plate and a large and very negative when full set of doubles.
Rather than adhere to a general rule like no steel tanks with a wet suit, it makes more sense to look at things from a systems perspective and assess whether your entire configuration makes sense and make adaptations and changes when the situation dictates - ie switching to an AL rather than SS plate in warm water or perhaps diving double AL80's rather than a more negative set of steel tanks in warm water if the dive profile allows.
In general though getting a total wing failure is rare. I have had the rear dump fail open and have had to ascend vertically to keep the air trapped in the wing (the main reason wings do not have shoulder mounted dump valves is that you do not want a failure prone valve that high on the wing where it would prevent air trapping). A large hole high in the wing could be problematic, but is unlikely unless you are crashing around inside a wreck and generally using less than ideal technique.
In any case, whenever possible a recreatonal diver shouldl weight themselves so that they are neutral at their 15 ft safety stop with no air in the BC and aboput 500 psi in the tank. This will ensure that they are not overweighted. The overweighting problem comes from a tendency for instructors to address technique issues, like the diver un knowingly finning at the surface, by adding more weight - and then of course advising the new diver to track the weight required in their log so they can continue to be over weighted. Another cause is weighting for a new wet suit that will becomes less bouyant after several dives that cause some permant crushing of some of the neoprene bubbles. The moral of the story is to repeat the bouyancy check at 15 ft whenever you get the chance and if you find yourself sinking with no air in the bc and only 500 psi in the tank, you are now to heavy and need to lose a pound or two of weight.
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