Yet another Buoyancy Thread

I didn't want to hiijack the other thread I can see as it was as much about photography as buoyancy.

Obviously the continual message with Buoyancy Control is practice, practice, and more practice. However, I was wondering if anyone had a specific tip for my buoyancy issues on the weekend.

I'm a fairly new diver, and to date all of my diving had been in warm water - holiday diving basically. I've never really had an issue with buoyancy control (well apart from my first dive). Not saying I was perfect by any imagination, but it's never something i've struggled with significantly.

Anyway, on the weekend was the first time i had cold-water dived, and it was as I was doing a Nav course. It was also the first time i've used this BCD and wetsuit.

The course was all in water @ ~2m depth, and i was wearing a 5/7 semi dry suit. I had on 24lbs of weight, which is far more than i've ever worn before obviously. The issue I had was that i could achieve acceptable buoyancy while swimming forward, but if at any time i had to stop to take a compass heading, i'd start to head toward the surface, even if i didn't change my body position.
If I tried with less air in the BC, i'd be bouncing off the bottom the whole time. So it became frustrating as i had to stop, immediately try to dump air out of the BC, take a reading, inflate, and start swimming. Which just made it frustrating.

I noticed the other divers weren't having the same problem, and my overall air usage was just as good as the best in the class, so I don't think i was over-breathing or anything.

Is diving in such a thick suit in such shallow water just something that will only come with practice? Or was I over / under weighted?

Sounds like my 4 checkout dives--but I know now that we were all overweighted. I assume you have done a weight check with your new equipment. There are ways to fine tune trim, consider different fins, etc. But once you are properly weighted--that's the main thing-- it shouldn't be long before you are doing fine in the shallowest of water or right near the surface. You may need a little practise with amounts of air in the BC at that point, but not much. That was my experience.

Short answer: yes, maintaining buoyancy in thick wetsuits takes practice. It becomes more difficult at shallower depths.
You're weighting sounds like it's in the ballpark, but no one can really say for sure unless they're there with you.

From the sounds of things, I don't think you're in full control of your buoyancy. If you're only able to maintain your depth by swimming then is sounds to me that your hydrodynamic profile is what's keeping you at depth, not your buoyancy control.

Definitely play around with you're BC input/output and make sure you can activate all your dumps reliably; that will make experimenting much safer. Sometimes you just need to hold down the inflator just a feather to get a tiny squeak of air instead of tapping it for a blast of air.

Make sure you're breathing is calm and you're not exhaling in one big "whoosh". You may be even with the best SAC in the group, but that doesn't mean you're breathing the same. Some people have bigger resting SAC's because they're lungs are just bigger. So a person with smaller lungs breathing heavy might strike even with a person sporting bigger lungs but breathing less frequently. Their SAC's will be the same, but the ratio of SAC: Lung Volume will be different.

You should also try to hover in a horizontal position, parallel to the surface. This will put your weights, wetsuit, and BC at the same depth, making less of a buoyancy difference throughout your entire body.

Stopping is such a wonderful thing. Only when you stop, do you really know where your buoyancy is. What you learned is that you were swimming yourself down all the time. Now, if your gear is such that you assume a head-down/feet-up position in the water, any swimming you do will drive you downward. If you don't stay positive, you WILL hit the bottom.

I don't know where you had your 24 lbs (and that sure sounds like an awful lot of weight for a 5/7 suit -- it's about what we put on our OW students wearing 7 mil Farmer Johns, and thus 14 mm of neoprene on the torso) or what kind of tank you were using, but rig imbalance may have played a significant part in your problems.

What I would recommend is first to do a real, formal weight check in the gear you are using. You can do this with a full tank; weight yourself to where you float at eye level with a full tank, and then add a pound for every 13 cubic feet of air you intend to use during the dive. (With an Al80, that's about 5 lbs.) After you have the correct amount of total weight, get underwater and try to get as horizontal as you can. Head up, body flat, legs out behind you. Have your buddy confirm that you are, in fact, flat. Then stop moving. See how you tilt -- do your feet start up as soon as you stop? If that's the case, you need to move some weight around to achieve better balance. You can sometimes move the tank down, or put more weight on your belt. If all else fails, you can use ankle weights, or go to negative fins.

(In Puget Sound, the same type of problem is common, but ours is the feet-down diver who dives negative all the time because he's kicking himself up. Until the dive has good posture and the rig is at least close to balanced, you can't solve this.)

You should do a buoyancy check, like suggested above. Also, I found that when I started, I was overcompensating with the BCD to control buoyancy. Instead, what I do now is get decently buoyant and then change levels using breathing (obviously NOT holding your breath). In other words, more air in your lungs = up, less air = down. It works out and you make your air last longer that way.

It also helps if you stop near the beginning (or whenever you're having problems) and fix your buoyancy completely (e.g., breathing or BCD control) before moving on. It sounds like you're compensating for lacking buoyancy control by swimming forward without fixing the problem. Just pausing and fixing the problem completely might be a better solution.

OzGriffo:

Anyway, on the weekend was the first time i had cold-water dived, and it was as I was doing a Nav course. It was also the first time i've used this BCD and wetsuit.

The course was all in water @ ~2m depth, and i was wearing a 5/7 semi dry suit. I had on 24lbs of weight, which is far more than i've ever worn before obviously. The issue I had was that i could achieve acceptable buoyancy while swimming forward, but if at any time i had to stop to take a compass heading, i'd start to head toward the surface, even if i didn't change my body position.
If I tried with less air in the BC, i'd be bouncing off the bottom the whole time. So it became frustrating as i had to stop, immediately try to dump air out of the BC, take a reading, inflate, and start swimming. Which just made it frustrating.

I noticed the other divers weren't having the same problem, and my overall air usage was just as good as the best in the class, so I don't think i was over-breathing or anything.

Is diving in such a thick suit in such shallow water just something that will only come with practice? Or was I over / under weighted?

Click to expand...

Well, combining a new environment and multiple new equipments with a Nav course @ ~ 2 m depth seems like making it as hard as possible.

Anyway, if you were able to use the compass without changing body position, I guess I'd need video of these "dives" 'cause my imagination can not imagine your current descriptions.

Or you could post nearly every last detail...

Bring over-weighted makes things harder, but your biggest problem is newness.

The best way to achieve weightlessness is to stop and hover. If you stop and begin to rise then dump air. If you sink add air. Do this in small amounts, a squirt not 5 seconds of inflating/dumping.

You want that zone where you are still, and when you fully inhale you start to rise. But by then you have fully exhaled so you start to sink. But by then.... see how breath control works.

Unfortunately this is harder than it sounds, so it takes practice. It is also harder when you are overweight, but still very doable. You may want to practice this a bit deeper, say 15meters. The next part to this is trim.....

Thanks everyone, I guess i just need to get out in the water and play some more. And again, and again until I sort it.

I was diving with a steel 10L and Steel 12L tank. First dive i had 27lbs (12 in each ditchable pocket, 3lbs in the trim pocket). The LDS have given me 4x 6lb and 1x3lb weights so i coulnd't be very fine in the adjustments.

I dropped 3lb's of weight for the second dive and felt more balanced, but it just wasn't right.

All my previous diving was in the tropics with completely different gear. Even though i'm a novice diver with less than 20 dives, i did seem to have control of techniques described. I could swim over a reef, stop, take a photo with no issues. I learnt breath control to adjust my position up or down, and later figured out ascend and descend with body position. I have photo's of me diving taken by the GF and i did seem to be pretty close to horizontal, and I managed to dive the SS Coolidge without any trouble.

This last weekend with the different gear, semi-dry and much more weight, i just couldn't get it to work. Stop, and i'd float. Get neutral, and then i'd hit the bottom when finning. It was so annoying I felt.. incompetent in the water Or maybe it was just that i was spending too much brain power on navigating.

But it now seems obvious that I must have been finning in a downward position, so this weekend i'll start with a full bouyancy check, then make sure I get my buddy to check my attitude and see how I fare.

Thanks all.

While being properly weighted is where you want to be but just being overweighed will not cause this issue. If you are neutral you are neutral, your BC is compensating for the overweighting. Being overweighed does make things more difficult however. There are a couple of things that can cause you to do what you describe, swimming angle or changes in your breathing. Being negative and sinking when you stop is the most common swimming issue and since you are starting to rise, my guess is you are either taking a larger than normal inhale or more likely unconsciously holding/pausing your breath. This is fairly common when new divers start task loading and shift their attention from diving to some other activity like setting a compass or adjusting a camera.

OzGriffo:

Thanks everyone, I guess i just need to get out in the water and play some more. And again, and again until I sort it.

I was diving with a steel 10L and Steel 12L tank. First dive i had 27lbs (12 in each ditchable pocket, 3lbs in the trim pocket). The LDS have given me 4x 6lb and 1x3lb weights so i coulnd't be very fine in the adjustments.

I dropped 3lb's of weight for the second dive and felt more balanced, but it just wasn't right.

...

But it now seems obvious that I must have been finning in a downward position, so this weekend i'll start with a full bouyancy check, then make sure I get my buddy to check my attitude and see how I fare.

Click to expand...

IMHO, "balanced weighting" for a beginner is typically "symmetrical weighting", so the dive shop giving you just one 3 lb weight, and 5 total pieces of weight, is odd.

I typically "train" my beginners to have their head lower than their feet, giving "some" downforce with forward movement. When you stop swimming you are a little positively buoyant, but a good exhale is all that's necessary to abort ascent until you can vent a little air from the BC.

Timing the breaths is the real control.

I'd be interested in more details about a Nav class that is "all in water @ ~2m depth"