Drysuit Buoyancy

[TartanFrog]

I read all the literature, talked with lots of people including the instructor, watched the video and they all said the same thing. Bouyancy in a drysuit is completely different than when in a wetsuit. WOW, were they ever right. I felt like a total beginner all over again. The escapes were no problem and maintaining bouyancy while moving was not an issue, but trying to hover was so ugly! I could not believe how bad it could be when the air started moving around inside the suit.

Oh well, good thing that was just the beginning. Lots more time practicing. Oh darn, I have to go diving.

 

[MaxBottomtime]

You will soon learn that it's so much easier to use your BC for buoyancy as it was intended and only put enough air into the suit to relieve the squeeze. Then, it becomes no different than wetsuit diving, other than the cold.

 

[krawlings]

once you figure out how to control the air bubble and feel how it feels to start to migrate fron one point to a nother. you will be able to keep it under your control not just rangum and moves at it ,. Dive Dive Dive it jets better each and eavery time :But remember this you will have some great dives and then there are the ones that just push you new skillsnmmnmn
GOOD LUCK AND INJOY

 

[DwayneJ]

I don't agree with PADI drysuit training - I only add just enough air to the drysuit so that the squeeze is not uncomfortable and use my BCD for buoyancy control. I do not have a big air bubble floating around the drysuit.

The problem with using a drysuit for buoyancy -
1. A bubble can move from neck to feet thus limiting your orientation in the water.
2. Somewhat unstable.
3. Keeping buoyancy in a drysuit means closing off the dump valve - You then have to manually manipulate the valve to dump excess air. The dump valve should be around 50% open so you can dump easily with a lift of the shoulder on ascent.

As a side note, I would validate weighting - You may be carrying too much if you need a large amount of buoyancy during your dive.

Dwayne

 

[TartanFrog]

Thanks for the inputs! I have wondered about using the BC in addition to the drysuit. But as stated, that is not what is taught in the course. So I will continue to practice and find what works for me.

 

[KevinHoward]

I agree with you when it comes to PADI's approach. I, like many others, only add enough air to my dry suit to be comfortable from the squeeze. My BC is my primary buoyancy compensator. The rest was just practice. So substitute for tank time.

 

[TSandM]

I think, if you're pretty good with buoyancy in a wetsuit, it's easier to do the "BC primary, air in suit to relieve squeeze" approach. When you get more facile with managing the suit, you can put more gas in it if you want -- it helps you stay warmer.

 

[knowone]

Tie some rope around your waist.

 

[Bubbletrubble]

I don't agree with PADI drysuit training - I only add just enough air to the drysuit so that the squeeze is not uncomfortable and use my BCD for buoyancy control. I do not have a big air bubble floating around the drysuit.

To give the OP another data point, I think it's useful to experiment with both methods: (1) using the drysuit only for buoyancy and (2) adding just enough gas to the suit to offset squeeze then add air to the BCD to effect buoyancy changes. There are times when it makes sense for a drysuit diver to run more air inside the suit to stay warmer. In my single tank configuration, I find that adding enough gas to my drysuit to offset squeeze is just about enough to establish neutral buoyancy at depth. YMMV.

The problem with using a drysuit for buoyancy -
1. A bubble can move from neck to feet thus limiting your orientation in the water.
2. Somewhat unstable.
3. Keeping buoyancy in a drysuit means closing off the dump valve - You then have to manually manipulate the valve to dump excess air. The dump valve should be around 50% open so you can dump easily with a lift of the shoulder on ascent.

I agree with #1 and #2. #3 is inconsistent with the way my dump valve works. I have a Si-tech brand valve oriented on the upper left arm of my drysuit. When I'm in my normal diving position (horizontal in the water column) with a single tank configuration, I can leave the exhaust valve fully open, yet still keep more than enough air inside the suit to remain neutral. When I need to dump air during ascent, I simply rotate my right shoulder down (moving my left shoulder up) and air is exhausted through the valve. I can't remember the last time I had to push on my exhaust valve to dump (manual operation). The auto-dump feature works great.

As a side note, I would validate weighting - You may be carrying too much if you need a large amount of buoyancy during your dive.

DwayneJ brings up a very good point here. New drysuit divers need to ensure that they are properly weighted. Conducting a proper weight check is complicated by the fact that it's best to do it in a horizontal position (in a vertical position, air will get squeezed out of the lower part of your suit and escape through the exhaust valve) and your weighting requirements will vary with how much air was inside your suit at the time of the weight check.

 

[lord khram]

The point about weighting is so important. I was initially told on my drysuit course that I would need extra weights ('try around 3 kilo extra') to what I had been using with my old 7mm semi dry suit, also I would need ankle weights.
It obviously depends on the particular suit, and indeed undersuit, but I very soon found what I was tought to be incorrect, and actually managed to reduce the weight in my harness by around 3-4 kilo. Upon finally getting my weighting correct I found I was infact needing to add so little air to the suit, indeed as others have suggested (contrerary to what I was tought) I reverted back to using my BCD for minor underwater adjustments, then after a few more dives with the new suit, and without the excess air moving around in my suit making me unstable in the water I also found the ankle weights to be unnecessary.
I gained more knowledge about drysuit diving by simply going on a days diving with a friend who was experienced in such, than I learned from the course, my friend pointed out simply by watching me dive the problems and we rectified them on the second dive, followed with a little fine tuning to the weights over my next few dive trips everything was soon ok.
Why was my instructor unable to do the same? PADI drysuit speciality - forget it, just another nonsensical speciality course.