Fine tuning of buoyancy distribution.

[Frosty]

Hey folks Ive gotten into open sea swimming.Part of this is getting your body as streamlined as possible.
my swimming wetsuit is very different from a scuba suit but it got me thinking a bit about scuba suits
Mens swim suits have 5mm of rubber in the legs and 2mm round the arms to give extra buoyancy to the legs.
I got to thinking that might be a great way to fine tune yourself for scuba dives.More leg insulation to make legs more boyant and less if you have floaty legs

 

[DA Aquamaster]

The problem is that neoprene compresses at depth, so the deeper you go the more the neoprene compresses and the more buoyancy you lose.

A better approach is to use fins that are less negatively buoyant. For example, I'm a big fan of XL sized Scubapro Jet fins, but they are heavy fins. As a result, in some configurations I have to switch to OMS Slipstream fins to trim out properly. The Slipstreams have the same blade design as the Jet Fins, but in a lighter monoprene material. The blades are a little stiffer, but the swim characteristics are very similar.

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On a related note, with a small wing, the temptation is to increase wet suit thickness to add more buoyancy to let the wing support larger, heavier steel tanks.

That works to an small extent provided you are:

1) not having to add additional weight to maintain neutral buoyancy at the end of the dive, and
2) you still have enough lift in the wing to achieve neutral buoyancy at depth with a full tank, and as the suit ages a bit and loses buoyancy anyway.

After a few dives to 200' for example, I find my 5mm wet suits end up as more or less 3mm suits.

 

[tbone1004]

the other concern is that you need the insulation around your core and that much neoprene restricts movement in your legs. Like what Larry said, the compression at depth kind of ruins the advantage you'd have at the surface like you do with a triathlon wetsuit. Much better to use static trim adjustments than to use neoprene to adjust it. Plenty of things you can move around that will fix it, but it is very important to know that it is essentially impossible to maintain horizontal trim with your legs extended like you have with a flutter kick. Moment arm shifts too far down and no amount of lead can fix it, you have to get into that "skydivers" position in order for your trim to balance out.

 

[TMHeimer]

I always question why there isn't some sort of "ankle floats" for scuba divers that would be sold at the LDS. Perhaps something fairly thin that wraps around the ankle or calf, maybe made out of styrophoam or related material that is thin?
Anyone know the physics about styrophoam's compressability, or any theories on why nothing like this is available?

 

[DevonDiver]

Because ankle floats would probably cause a drastic increase in fining workload?

 

[tbone1004]

have you seen coffee cups that have gone to depth for fun? I have a pair of them, one that has been to the Titanic, and another to somewhere quite deep in the pacific. They're almost thimble sized.... Open cell foam doesn't work. Closed cell doesn't either because while it may work at the surface, it stops working so well at depth.

In the immortal words of Chris Richardson that is an equipment solution to a skills problem. The skills problem coming from piss poor instruction

 

[boat sju]

I'm a big fan of a 1# ankle wt placed on the tank valve. Anything on your ankle will also cause resistance to your finning.

 

[TMHeimer]

have you seen coffee cups that have gone to depth for fun? I have a pair of them, one that has been to the Titanic, and another to somewhere quite deep in the pacific. They're almost thimble sized.... Open cell foam doesn't work. Closed cell doesn't either because while it may work at the surface, it stops working so well at depth.

In the immortal words of Chris Richardson that is an equipment solution to a skills problem. The skills problem coming from piss poor instruction

Not necessarily. Could be poor selection of fins for those heavy legs--that were bought long after instruction. But it could be poor instruction in a lot of cases.

 

[TMHeimer]

Because ankle floats would probably cause a drastic increase in fining workload?

Could very well be. Unless there was some material that is buoyant and extremely thin?

 

[TMHeimer]

I'm a big fan of a 1# ankle wt placed on the tank valve. Anything on your ankle will also cause resistance to your finning.

Agree, and we do this at times for OW students. Don't see how adding weight to the top area of a tank helps with heavy legs. Wait, my head's on backwards today--of course the ankle weight on valve counteracts heavy legs.