Buoyancy problems – can’t get horizontal,

[Suzana]

Hello all,

I am still quite a ‘newbie’ but after 25 dives I think that my buoyancy could be better. On my last trip I dropped some weight and that made things much better.

My main problem now is that I seem to be kind of ‘bottom heavy’. Especially in the beginning of the dive - I find it difficult to stay in a horizontal ‘stream lined’ position. As soon as I stop somewhere to have a look at something my body tends to tip up and my feet get close to the ground. Most of the time I manage not to actually hit the bottom with the feet but I often need to fin hard and I sometime stir up sand – not very professional. :upset:

I am guessing that this problem is caused by the fact that I am a woman with a rather large cup size – and I suppose they make me float.

For some reason this problem seem to get better at the end of the dive when I am getting lower on air.

So my question is, are there any weight systems or techniques that could help me overcome this problem?

 

[Bob3]

Your tank has different buoyancy characteristics when it's full & empty, total weight swing for an 80 cubic footer is about 6 lbs.
Try hiking your tank up a little higher in your backpack.
You don't want it smacking the back of your head, but for some odd reason I see a lot of folks with their tanks slid way down, like a rapper fashion statement.

 

[roakey]

See: http://www.scubaboard.com/t8232/s.html

Roak

 

[Charlie99]

Suzana once bubbled...
Buoyancy problems – can’t get horizontal, ....

Don't forget that you need to control both your trim and your buoyancy. From your description, it sounds like you aren't really neutral buoyant. Trying to correct trim is difficult until you are truly neutral.

Step one is to simply stop ALL motion. No hand waving, no finning, no wiggling of ankles. Just let your body roll/tilt/or whatever. This sounds simple, but an amazing number of people can't stop moving.

As you continue your normal breathing pattern, you should be ascending a foot or two and then descending back that same foot or two, as you breathe in and out. If this isn't happening, adjust the amount of air in your BC. Getting, and staying, neutral is much, much easier if you are correctly weighted. Extra weight means extra air in the BC, which changes volume and lift as you ascend and descend. Keep taking a pound off with each dive until you have to alter your breathing pattern towards the exhaled end in order to stay at your safety stop.
Another indication that you are overweighted is that you any air whatsoever air in your BC at the safety stop and 500psi in your tank.

Once you are truly neutral while pefectly still, then you can analyze what you need to do for trim.

A lot of the time, you can fix your head up/head down trim simply by moving the tank higher or lower. Airheads like me might also need a couple pounds in trim pockets or up on the tank itself.

Charlie

 

[detroit diver]

I don't know what type of equipment you are using, but your BC may not be helping the situation. Some are just not built for horizontal trim. In fact, they praise themselves on how well they float you vertically on the surface. Those two don't mix very well, IMO.

If it's not the BC, then it's just a lot of practice and fine adjustme of weights. Get some pool time and play around.

 

[The Chairman]

it's usually as simple as sliding the tank forward to make you tilt forward and back to make you tilt back. Imagine your tummy as the middle of a see saw to visualize what you are doing. In fact, I can adjust my trim during a dive by utilizing my legs. Pull them in and my head just naturally rises. Extend them out and I go horizontal with my toes just higher than my head.

I have yet to put on a BC (back inflate, vest or BP/wings) that I could not easily adjust to neutral weighting and then adjust my trim to horizontal. Don't go blaming equipment for bad technique. Remember... weighting will position somewhere up or down in the water column... trim will make you horizontal (or not).

 

[victoriawtx]

although I do agree with the others that technique and proper weighting is also involved. I know that in the past I had used an ill-fitting BC that made me feel like a ungainly elephant in the water. LOL When I switched BCs it made an enormous difference in my trim, like night and day.

good luck!

 

[MgicTwnger]

The following were the steps I took to improve my bouyancy & trim control:

PADI (I know, don't say it ) Peak Performance Bouyancy course.

Switching from jacket-style BC to a Seaquest Balance, weight-integrated w/trim pockets.

Diving, practice, diving, practice, diving, practice, diving, practice, etc.

 

[HammerNoMore]

Suzana,

I can certainly understand your problems. I had them myself. I started diving using a Zeagle Ranger. I never really had any problems with my bouyancy but like you, whenever I stopped finning I always returned to vertical.

The first thing I tried to fix my trim was to slide the tank up as others have suggested. This may work for some but it certainly did not for me. First, moving the tank up to the point that it bumped my head every time I moved did not solve the problem. Second, when diving with AL80's they start negative and end up posetive. So moving the tank further north might help at the start of a dive and hinder at the end of a dive.

My next step was to play with weighting. I bought the trim weight pockets and cam band weight pocket for my BC. By carfully moving weight around, I was able to rectify the situation. The problem is that it is something that requires tweaking every time you change things like thermal protection, etc.

This is one of the 2 reasons that prompted me to move to a BP/Wing config. With the steel plate on my back and closer to the center of gravity, I have never had a trim problem since.

James

 

[jhelmuth]

The distribution (and amount) of body fat can play a significant role in trim (as posted earlier - neutral buoyancy is an issue of where you are in the water column) for some people. Adjustments to tank position, weighting distribution in the upper torso and waist (I agree with all who post that you should never require ankle weights if your trim is correct), selection of equipment (e.g. - many DMs are using light-weight full-foot snorkel fins due to their trim benefits as well as power benefits in some models). Don't underestimate the power of trim. Choose the right equipment. For most people, their legs are the "leanest" part of their body. This makes that portion naturally lower in the water column when compared to the upper body which has the additional buoyancy of the lung cavity. If you are physically fit and have a good body shape, you will find that buoyancy control and trim are much easier - another benefit of being in good physical shape/condition.
For many, distribution of body fat is roughly similar. So similar gear configurations (in terms of weight) are good choices. This is not always so for every diver. Women with larger cup sizes do face additional trim problems that most do not. For you, weight distribution higher up in the torso and/or tank adjustments will be required to compensate. Follow the wise advice you were given in trying out different gear and find what works for you. You really should take the time to carefully consider the impact of your choices in configuration and how that will change your trim - then adjust accordingly.