Dry Suit and Buoyancy Control

[Jim Lapenta]

First thing I would do if I was your instructor would be to take you in the pool and get you properly weighted in the just the suit and then add the BC. Spend 3-4 hours working on adding and venting air with both the BC and the suit combined and individually. Then do the recovery skills and finally OW dives. If you are having issues in that last 1/2 atmosphere you probably did not spend enough time in the pool learning to really use the suit.
I am weighted so that I can vent from both the BC and the suit as needed. It's venting both at the same time on many occasions. Also do as much of the ascent horizontally as possible rather than vertically. Without seeing you in the water it's hard to tell where the problem is. Too much air, not enough weight, improper technique, etc. Get with a good drysuit instructor and have them do a dive with you.

 

[sea_otter]

Can you describe your venting procedure as you ascend?

My current problem is losing the slow ascent battle at 15-17 feet. I'm thinking I need to complete de-air the suit as a first step in ascents and, then, manage with the wing.

The last few feet are certainly the most difficult, as you have the highest change in pressure. I keep my drysuit vent fully open. As you ascend, raise your left arm and bend it to squeeze any remaining air out of the forearm. Even if your suit is "completely empty" at 30', you'll still be venting it on the way up.

I've been practicing making a short stop every 10' (I have signed up for a GUE fundies class in the near future, and I'm trying to get comfortable doing this ahead of time). It is a good exercise to make sure your buoyancy is very well controlled while ascending slowly.

Here's a video of someone making it look really easy (jump to 2:00):
I've done only 6 dives so far with my drysuit. Each one is an improvement, and I'm finally starting to get the hang of it. I'm nowhere near as good as she is.

 

[Cowtown44]

First thing I would do if I was your instructor would be to take you in the pool and get you properly weighted in the just the suit and then add the BC. Spend 3-4 hours working on adding and venting air with both the BC and the suit combined and individually. Then do the recovery skills and finally OW dives. If you are having issues in that last 1/2 atmosphere you probably did not spend enough time in the pool learning to really use the suit.
I am weighted so that I can vent from both the BC and the suit as needed. It's venting both at the same time on many occasions. Also do as much of the ascent horizontally as possible rather than vertically. Without seeing you in the water it's hard to tell where the problem is. Too much air, not enough weight, improper technique, etc. Get with a good drysuit instructor and have them do a dive with you.

Sounds like good advice. I'm thinking its multifactoral. What pool drills would you recommend after ensuring proper weighting and not adding too much air to the suit?

 

[KevinNM]

Hover a feet off the bottom in the deep end with enough air in the suit to prevent squeeze and enough in the BCD to get you neutral. Try to not move, ensure you are neutral as you breath in and out. Inhale deeper and allow yourself to go up by 5 feet. Try to stop at 5 foot increase, so you need to vent air from the suit and BCD appropriately. If you vent too fast you'll get stuck short, if you vent too slow you'll overshoot or find yourself at the surface. Then drop back down and stop back at the same distance from the bottom. Play with this until it works reliably.

If your pool is like the ones around me a 5 foot rise would have you somewhere between 5-9 feet of depth. Once that works, try to go from near the bottom to closer to the surface. The closer to the surface you try to stop and the farther up you go before you stop the harder this gets, so trying to go from 12 feet to stop at 2 feet is really pretty hard for me.

Also go to the bottom and point your head slightly down and your feet slightly up. Add air to the suit until you start to go up feet first.

There are two objectives to this. First, you need to learn how to get your feet under you, because everyone eventually ends up starting a feet first ascent during a real dive and you need to learn how to stop it. Don't worry about staying flat in the water during this, you may need to somersault or something similar to get your feet under you so you can vent the air. Second, you want to learn how to recognize the whole "floaty feet" feeling before you start to go up so you can fix it when it's a trim issue and not a buoyancy issue.

 

[Reku]

I use just enough air in my suit to not strangle me - then use the bcd for the rest.

 

[coralreefer_1]

First thing I would do if I was your instructor would be to take you in the pool and get you properly weighted in the just the suit and then add the BC. Spend 3-4 hours working on adding and venting air with both the BC and the suit combined and individually. Then do the recovery skills and finally OW dives. If you are having issues in that last 1/2 atmosphere you probably did not spend enough time in the pool learning to really use the suit.
I am weighted so that I can vent from both the BC and the suit as needed. It's venting both at the same time on many occasions. Also do as much of the ascent horizontally as possible rather than vertically. Without seeing you in the water it's hard to tell where the problem is. Too much air, not enough weight, improper technique, etc. Get with a good drysuit instructor and have them do a dive with you.

That is exactly what I have been doing the last few weekends. My instructor teaches diving to Physical Education students at a nearby university, and for the past two Saturdays I've been going to the pool with them just to get in the water and practice with the suit, releasing the safety sausage..and a few other basic things I wanted to improve more.

I feel a bit more comfortable now that I did when I made the updated post. I had much better control and success with venting that previous dives, and it was the first dive where I wasn't training and could just take my time and work on what I wanted to practice. As an added bonus I got to hang around with my instructor while he was teaching others and help spot gear setup mistakes and otherwise assist on a totally non-professional level.

 

[abyss_scuba]

Sorry it took me so long to get back to this thread but I have been busy with work. Bob talks about the dry suit valve dumping slower than the BC and uncontrolled ascents.

First thing I ask is how much air are you putting in your bc? I wear a 36 ld wing lets move on up to a 45 lb wing. For each cubic foot of water you displace you gain 64 lb of lift so a 45 lb wing has a volume of 8" x12"x12" when I displace that amount of air through my dry suit we are not talking about a lot of air and that is if you needed a full wing, something I have never done. So if I needed half of that it would be 4x12x12. Again not a lot of air. Having dove with a dry suit since 1993 I have become quite comfortable using my dry suit for buoyancy. Now if for some reason you find yourself making that uncontrolled ascent every one talks about you burp your suit through your neck seal. You did learn this in your class right? Not saying my way is right and your way is wrong, just what I am used to. More important is dive, dive dive, find what works for you and stick to it unless you find something better then. Dive dive dive keep reexamining what you do and keep and open mind.

 

[coralreefer_1]

Sorry it took me so long to get back to this thread but I have been busy with work. Bob talks about the dry suit valve dumping slower than the BC and uncontrolled ascents.

First thing I ask is how much air are you putting in your bc? I wear a 36 ld wing lets move on up to a 45 lb wing. For each cubic foot of water you displace you gain 64 lb of lift so a 45 lb wing has a volume of 8" x12"x12" when I displace that amount of air through my dry suit we are not talking about a lot of air and that is if you needed a full wing, something I have never done. So if I needed half of that it would be 4x12x12. Again not a lot of air. Having dove with a dry suit since 1993 I have become quite comfortable using my dry suit for buoyancy. Now if for some reason you find yourself making that uncontrolled ascent every one talks about you burp your suit through your neck seal. You did learn this in your class right? Not saying my way is right and your way is wrong, just what I am used to. More important is dive, dive dive, find what works for you and stick to it unless you find something better then. Dive dive dive keep reexamining what you do and keep and open mind.

I do not recall being taught about purging the suit via neck seal in the case of an uncontrolled ascent when I took the specialty. Then again though I may very well have beenn told that and it got lost in translation. ( I am learning in Korean by a Korean instructor,and while my Korean is above average for a foreigner is still not fluent and some things slip by me). For example, I actually had my first pool session for rescue diver course today, and while we were going over the breathing for an unresponsive diver in the water and doing the 5 seconds, give breath, release a harness in 5, give breath...etc...i did not realize that when my instructor was flinging his hand on 3-4, that he was doing so to remove water from his hand/fingers before closing the nasal passage as to avoid getting water in the nose. I thought it was just some thing he was doing to keep count when i first observed it. Turns out he explained it earlier but i totally missed the reason WHY he was doing it.

I could have taken my course today in a wetsuit, but I chose the dry suit because i wanted the extra challenge of it in regards to just one more thing to consider when removing gear from a victim. I haven't been back in the ocean in the drysuit since the update, but i feel at least a bit more confident that I have been able to bleed more consistently and successfully than before. ( granted, its the pool) As you say, all I can really do at this point is dive it and get more comfortable. I will keep your comment in mind however about the emergency release via the neck.