Using your drysuit as a BC

[mempilot]

String is my kind of diver. Sounds like he's been doing this for awhile. Diving is easy if you do it right.

Interesting comment. Using equipment for what it was designed for is doing it right. It doesn't get any simpler than being properly weighted, take the squeeze off, and dive. If you need the lift, put a little in the wing. PADI's drysuit course doesn't get a lot of respect from tech divers for obvious reasons.

If you'd like to know what kind of diving the rest of us do, just ask. You might be surprised by our experience as well.

 

[mempilot]

Uh ? To dump air from my drysuit i raise my left arm. No buttons to press, no tubes to find, no pull cords to find...Raise arm....Dump air. It cant get any simpler than that.

Raise inflater hose.... Dump air. If you can't find that 'tube' as you call it, then you might not want to be diving at all. If you can't find a dump cord by memory and feel, then I'd say the drysuit is probably too complicated for you as well. Sorry to be course, but come on. What are going to do if your suit dump valve fails? Break the seal? Now you have water flowing in your suit. You just made your life more difficult, not simpler.

 

[jcclink]

All the modern drysuits I've seen have an adjustable auto deflate valve usually on the left arm. Like String said, all you have to do is raise your arm. If your suit isn't set up this way, then diving is more difficult than it has to be. If it doesn't vent fast enough during ascent, either it isn't adjusted properly or you're ascending too fast.

 

[mempilot]

I figure this should start a lively discussion.

More of a troll me's thinks.

 

[Yerba Mate]

All I know about this is that from my experience with my suit. I dive a White's Quadflex (laminate) suit and a Zeagle Ranger. I use a correct amount of weight (determined empirically), I dive singles exclusively at this time, and I do have relatively few dives in my logbook. I don't necessarily use my suit for bouyancy but it works out that way.

I find that the amount of air I put into my suit to offset squeeze (and adding a bit more for warmth), takes care of my bouyancy pretty good. I personally can't stand it when I'm a marshmellow either, so if for some reason I need a bit more that that, I put it into my BC. However, almost always it's perfect putting air into my suit. I don't know...Maybe I'm weighted properly and maybe it has to do with the fact that my suit has no inherent bouyancy, but that's how it is.

Also with the dumping air deal, I find that dumping air from my suit is easier than dumping air from my BC. Both my BC and my suit dump at basically the same speed, and although my BC has more places to dump, my suit has a valve on my forearm that dumps whenever I put my arm up (which I can of course turn down if I want).

Regarding this argument, my opinion is as follows. It doesn't make sense to use the suit for bouyancy just to avoid using the BC (that results in way too much air in the suit). But it does make sense to use the suit for bouyancy if using the BC is unnecessary. Why would I cause excessive suit squeeze on myself, just to put that air into my BC, when putting it into my suit will offset the squeeze and not cause the suit to be difficult to use?

 

[pipedope]

If doing deep, long dives with large amounts of gas it is probably somewhat better to use the BC to control bouyancy and put just enough air in the suit to keep the squeeze off.

Most recreational diving it doesn't make much difference.

Some sidemount divers don't use a BC at all. They do bouyancy control with the suit.

There are a number of commercial diving situations where the suit is used for bouyancy and no BC is worn.

Pick the best system for the dives you are doing and the buddies your are diving with, and practice so you are good at it.

 

[jcclink]

Don't start the DIR thing - we'll be here all night.

 

[mempilot]

Yerba,

You got it right. Properly weighted, you won't need to add air to your bc diving singles at recreational depths. Go deeper with a large single or doubles, and you'll need the lift that the bc affords you. Go over a wall down deep, get into an uncontrolled desent, and try to use your suit to arrest the descent. Bad news. There is a reason for both pieces of equipment. Using one vs the other for most divers isn't neccesarily a big deal. Until you rely on that improper use when you really need it. Dumping air from the bc should not be a difficult task. I question whether people really have this problem, or if they are just using it for arguments sake.

 

[mempilot]

If doing deep, long dives with large amounts of gas it is probably somewhat better to use the BC to control bouyancy and put just enough air in the suit to keep the squeeze off.

Most recreational diving it doesn't make much difference.

Agreed.

Some sidemount divers don't use a BC at all. They do bouyancy control with the suit.

I assume you're talking about cave and some technical wreck penetration. I doubt our poster knows anything about sidemount divers. Very specialized rig setup.

There are a number of commercial diving situations where the suit is used for bouyancy and no BC is worn.

Again, this is so far from recreational, that it will cloud the discussion on recreational and technical diving.

Pick the best system for the dives you are doing and the buddies your are diving with, and practice so you are good at it.

Agreed. But I've seen whole groups of divers following bad procedure, so make sure what you do isn't dangerous. I'm not saying what is being discussed is absolutely dangerous, just know what you're going to do in an emergency.

Pipe,

I'm not questioning you or really anyone. Just making sure the original poster understands both sides. He hasn't chimed in a while anyway, so we're probably all just chatting amongst ourselves as usual.

 

[String]

PADI's drysuit course doesn't get a lot of respect from tech divers for obvious reasons.

Maybe not but PADI drysuit isnt the only way to go. Ive never done it for example. All our club is just taught by experienced dry suit users. FWIW theres roughly a 50% split in the club between "BC'ers" and "Drysuits" for buoyancy - both sides fight their corner religously neither giving an inch. We have several dives with several thousands dives to their names down to 50-60m, single cylinder/ponys who use their drysuits alone for buoyancy without problemsand we have others that wont do a 10m dive without using the BC. Both sides are very much alive and well and when you total up all the dives youd have to conclude that neither method is more dangerous than the other and its entirely personal preference.

Raise inflater hose.... Dump air. If you can't find that 'tube' as you call it, then you might not want to be diving at all.

That maybe the case but my response was a reply to the "more convenient to dump from a BC" line. Lets be honest here, raising an arm is as simple as it gets - how can anything be more convenient than that ! No buttons, nothing, just raise arm (i have a cuff dump).

The bc bladder has an overpressure relief

If you have enough air in a BC to trigger the overpressure valve you have far more immediate problems than a convenient way to dump air. You're looking at hitting the surface in 2 seconds flat. FWIW drysuits will all have an equivalent - over a certain pressure of air it will simply escape from neck and/or wrist seals. To trigger an overpressure in either of these requires a LOT of air - far smaller amounts than that underwater will rocket you to the surface.

Using equipment for what it was designed for is doing it right.

Dangerous assumption to make - My drysuit manual and many others ive seen all recommend using the suit for buoyancy and leaving the BC empty. Given thats come from the people that actually make the suits youd have to conclude from that the product was intended for this purpose.

What are going to do if your suit dump valve fails? Break the seal?

Exactly that, i'll let a tiny bit of air out through the wrist seal as and when needed. Its not big issue - a few people have NO dumps in their drysuit and dump by the wrist method without getting a suit full of water. Provdied there is air to dump and the inside is under positive pressure you wouldnt expect water to come flooding in and it doesnt.

Having said that i find it very hard to envisage my cuff dump failing, it has no moving parts save a plastic diaphgram that flexes upwards when the pressure on it becomes more than ambient. No springs, dials, screw fittings at all. The worst ive seen is the undersuit blocks it in which case shaking the arm or moving it a bit clears that. As an extra on my suit i also have a shoulder auto dump (normally fully closed as not used). I could use the manual dump press off that if needed. That said im thinking of removing this valve as i hate it.

I find that the amount of air I put into my suit to offset squeeze (and adding a bit more for warmth), takes care of my bouyancy pretty good. I personally can't stand it when I'm a marshmellow either, so if for some reason I need a bit more that that, I put it into my BC. However, almost always it's perfect putting air into my suit. I don't know...Maybe I'm weighted properly and maybe it has to do with the fact that my suit has no inherent bouyancy, but that's how it is.

Thats the point i was trying to make, a properly weighted single tank driver should be near neutral with squeeze removed in the suit and not require the use of the BC to sort it out. This doesnt apply to twinset and staged divers who typically have to dive overweighted especially at the start.

Go deeper with a large single or doubles, and you'll need the lift that the bc affords you.

Just how deep do you want to go ? Nearly all diving here is done with 15l cylinders which are fairly large and drysuit buoyancy has been used by people i know down to 50m, possibly more. None of them have had any problems. Ive personally used mine down to 40m again with no issues what so ever.

Pick the best system for the dives you are doing and the buddies your are diving with, and practice so you are good at it.

The most sensible comment so far.

This debate is likely to never end, just like the off-line people i know on both sides both will fight their corner totally and stick at it. Given the fact tens of thousands of dives happen world wide annually with some divers using drysuit, some using BCs, incidents are very few and far between (those relating to suit or BC problems) you have to take from that that neither method is particulary dangerous. Both have advantages over the other and disadvantages and there is nothing wrong at all with experimenting and deciding for yourself which method you prefer.

As i said ages ago on this thread, i spent all last year using my suit alone for buoyancy and this year experimenting using squeeze off on suit and BC for buoyancy. At the moment ive only managed 11 dives this year but im totally undecided as to which method i prefer. I notice no real difference.