In Reply to: Re: Why a 120? posted by Walt on October 23, 2004 at 22:00:19:
Walt has a great method for finding the right amount of weight. Then the question is; How much BC lift do you need one you are weighted correctly? The answer is just enough to compensate for the weight of the full tank, and a bit more for lights and camera.
9 lbs. for the air in a 120 ft3 tank {less for smaller tanks).
6 lbs. to carry a camera and a dive light. (usually less)
8 lbs. for wetsuit buoyancy change with depth (smaller for most wetsuits and unneeded for a dry suit)
TOTAL: 25 lbs. of lift is plenty if you are properly weighted. Most novice divers tend to use more weight than they really need, I think that is why many divers get told they need BCs with a lot of lift. If when you let the air out of your BC you drop like a rock you are definitely overweighed. As you gain experience the weight you need for Walt’s method will decrease as well because of your improved relaxation and breathing. Once you minimize your weight you will find your air consumption will drop some as well because you will have less drag when you move. I use a 18 lb. lift BC when I take pictures only because I could not find a 12 lb. lift model. When I don’t take the camera, I don’t even use a BC.