There are two dimensions (at least) to weighting

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Posted by Chuck Tribolet on January 12, 2006 at 18:45:00:

In Reply to: Re: Re: Take a drysuit class, and listen to experience. posted by Josh.C on January 12, 2006 at 15:35:21:

There are at least two dimensions to weighting.

The first and most obvious is getting the diver neutral.

The second is trim: the attitude of the diver in the water. If
the diver has their center of gravity lower than their center of
buoyancy, they will naturally float with their feet low. This
is the case for the typical diver with a typical BC and aluminum
tank. Have a neutral trim, that is, the diver naturally floats
horizontally in the water, has a number of advantages:
- When you kick, you are thrusting horizontally, not upwards at
an angle.
- You don't kick up the bottom.
- When hovering, either for a safety stop, or photography, or any
number of other reasons, you are presenting a large cross-section
to vertical movement, so vertical movements happen more slowly
and are therefore easier to control with small buoyancy
- Some of the techies think you offgas better when your body is
more or less at the same pressure. I'm not sure I believe this
but there doesn't seem to be any evidence that it hurts
So how can you adjust your center of gravity upwards?
- Steel tank
- Steel backplate
- Attaching some of your weight high on your body. For, me it's
most of the time a camera that's a couple of pounds negative,
or a two-pound ankle weight around the neck of the tank when
I'm diving without the camera. On tropical trips where I'm
stuck with an AL tank, I put about four more pounds up high.
- Lighter fins might make a difference I guess.

I dive with a steel backplate, steel tank, and the camera, and
that's what it take to get me into neutral (or maybe even a
touch head down) trim.


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