Travel BC question

Is there a rule of thumb concerning travel BC's vs full BC's as far as bouyancy?
To elaborate.....does a travel BC require more or les weight to achieve the same bouyancy as a full BC?
I have a Sherwood Freedom that I need 16# to get perfectly bouyant.
Will I need more weight to get the same result from an older Zeagle travel BC?

I'm not sure what the difference is between "travel" and "full" BCs, but probably the less padding, plastic, and fabric that a BC has, the less inherent positive buoyancy it will have, and should require less weight to sink. As BCs age, I would guess that there is some compression of the fibers and maybe they will lose some inherent buoyancy. Is that the question you're asking? Probably the zeagle will require a little less weight, if your current BC is bulky and the zeagle is not. It's hard to say but easy to test, just empty them, throw them in a pool, and add weight in the pockets until each sinks.

mksmith713:

Is there a rule of thumb concerning travel BC's vs full BC's as far as bouyancy?
To elaborate.....does a travel BC require more or les weight to achieve the same bouyancy as a full BC?
I have a Sherwood Freedom that I need 16# to get perfectly bouyant.
Will I need more weight to get the same result from an older Zeagle travel BC?

Click to expand...

"Travel" bc's usually feature less lift than "conventional" bc's because most people choose to travel warm sunny places.

Warm water means less exposure suit. Thinner suits will have less of a change in buoyancy than a thick wetsuit. Buoyancy Compensators are used primarily to compensate for changes in the buoyancy of the divers exposure suit.

Any bc needs to meet two criteria; offer enough lift to float the diver's gear at the surface if they ditch it. This should be calculated with a full tank.

I deal with BP&W's so I'll use one in this example. A medium SS plate and harness is about -6 lbs, a reg is about -2 and a full al 80 is about -2. That totals -10 lbs. In theory only 10 lbs of lift is necessary to float this rig at the surface with a full tank.

With an empty tank this rig will be about -4 lbs.

If you assume that this diver is in tropical conditions and is wearing a full 3mm wetsuit, their suit will only be about 4 lbs positive. This suit cannot loose more buoyancy than it starts with, that is a max of 4 lbs. This diver needs only 4 lbs of lift to compensate for a fully compressed suit.

In short in a thin suit with buoyant tanks our "example diver" only needs about 12-17 lbs of lift.

Contrast this with a cold water diver in a suit that might be 20+ lbs positive, and who might be using negative steel tanks. With a large single steel cylinder the rig could be -18 lbs or more if the diver adds ballast to the rig. The diver's suit can now possibly loose more than 20 lbs of buoyancy via compression.

In this case our diver needs more lift, with a 26-30 lbs lift bc a reasonable choice.

Tobin