drysuit tech diving

[martini_effect]

Hi guys...some advice please...

I'm a warm water pansy, with lots of warm water (30c) tech experience using a 3mm suit and double 12l aluminium or double 15l steel tanks.

I'm now acclimatising myself in a drysuit this summer, in order to make some cold water tech dives in late Sept.

Obviously there are 2 ways of controlling bouyancy / ascent using a drysuit and / or wing. and with the weight of double 15l tanks, obviously a fair amount of air will need to be added to compensate for the weight (which I will be practising in controlled conditions with no deco obligations)

anyway my point is....do you use 1 or both as bouyancy compensators. do you add air to the drysuit to avoid squeeze and then use the wing for neutral bouyancy, or do you use only the drysuit and just use the wing for positive bouyancy on the surface?

it seems to me that reeling in a line, dumping from a drysuit valve, deflating a wing and looking at a computer all at the same time is extreme task loading if you're trying to stay +- 50cm on a deco stop

any tips are welcomed...

 

[dannobee]

Add air to eliminate the squeeze only. Leave the BC to do its job-to compensate for bouyancy changes.

 

[Dive-aholic]

There's a difference of opinion on this subject. I think most agree with dannobee. I do. A wing is a buoyancy compensator. The dry suit is supposed to keep you warm. The only reason to add air to the dry suit is to eliminate squeeze.

 

[Doc Intrepid]

Coupla other observations:

Drysuits are not like BCs or wings; they have arms and legs. Depending on the type of undergarment you're wearing, whatever underwater issues you may be experiencing, and/or other parameters such as your body position (head down), etc. a drysuit valve does not exhaust gas as rapidly or completely as a wing or BC will. Beware of putting too much gas into a drysuit. Once you begin an ascent, unless you effectively control both your rate of ascent and your body position the gas in a drysuit is capable of expanding faster than the valve can vent it (e.g. you may be feet up, wrapped up in something, etc.) While it isn't inherently difficult to deal with, new drysuit divers may need a few dives to get it all figured out.

Dive such as those you're referring to in a drysuit place extra requirements on your ability to control your rate of ascent and your position in the water column. A drysuit valve is designed to vent automatically (assuming you dive with the valve dialed open all the way). Therefore, if you're horizontal in the water and rising at a slow and controlled pace, the valve will automatically vent excess gas as you rise. At most you only need to tense your bicep to cause the valve to 'burp' out gas. After a few dives you'll notice that this does not add to task loading..., but it's important to be able to control your body position and rate of ascent when making those sorts of dives in a drysuit.

Candidly, its likely that extremely cold water may give you more issues than your drysuit will, if you are basically a warm water diver used to Thai dive sites. You can get accustomed to your drysuit in Thailand, but be sure to leave yourself a few dives to get used to extremely cold water before doing any major drops! Hypothermia on deco stops sucks...



Best,

Doc

 

[scuba.ie]

Add air to eliminate the squeeze only. Leave the BC to do its job-to compensate for bouyancy changes.

Totally agree with this. Like to add, when I'm dropping down the line I hold my inflator hose in my left hand which I can operate with my ring and little finger to inflate, and I keep my middle and index fingers by my drysuit inflate button. That way its not a big deal finding one or the other while dropping, getting squeezed, checking depth, etc...

 

[jonnythan]

I think that contrilling the amount of air necessary to offset the weight of air in those big tanks inside a drysuit is awfully hard.

If you leave the drysuit valve way open, and use your BC for buoyancy control, it becomes very simple on ascent. Assuming your drysuit exhaust valve is placed in a good location, it will simply vent automatically as you ascend. It takes some practice, but it's not something you have to continually think about. It's way easier and less dangerous than maintaining a huge air bubble all over your drysuit.

 

[Tassie_Rohan]

Allow for around 10 dives to get the hang of the drysuit. Keeping a moderate squeeze in the drysuit will help you master the basics and keep the dump valve on full open.

As doc mentioned try to get some non-tec cold water dives in. Cold deep dives in low vis, with loads of lead and thick exposure protection hindering your movements and senses, is a totally different psychological realm to tropical diving. The more cold water dives you do the more comfortable you wil be when doing your exercises.

Cheers,
Rohan.

 

[tterry1]

What Doc Intrepid said. You really can get really really cold in a drysuit. Beyond that, I agree with the comments on using the wing for buoyancy control and the drysuit for warmth and squeeze.

 

[TrojanCatMan]

Why does some of the rec training agencies tell you to use your drysuit for bouyancy then? What your saying here makes way more sense!

 

[NSDiver]

When I took my Drysuit class I was told to use the suit for buoyancy, and leave the wing alone. About 15 dives later I started using the wing for buoyancy instead (very recently), and it's MUCH easier, even with the so called "task loading" of managing an extra air space.