How much weight
Proper weighting is achieved when a diver can hold a 10′ stop with no air in the BC and with 500 psi remaining in the tank. This insures that the diver can hold his last stop at the end of a dive, without the need of a buoyancy device.
Why overweighted in OW?
If the proper weighting is significantly
Effects of Overweighting
Carrying additional weight than necessary means that the diver needs to carry more air (buoyancy) was well.
When a diver ascends, this extra air expands and needs to be managed.
Let’s say that a diver is properly weighted and compensating for 2# of weight near the end of his dive at 100′. He ascends from 100′ to 33′ and now has 4# of lift in his wing, as the air in the BC expands from decreased pressure. In order to remain neutrally buoyant, the diver removes 2# of lift.
In the same scenario, let’s say that the same diver is over weighted by 4#s. At 100′, he is now compensating for 6#s of weight. When he ascends to 33′, the air in his BC expands to equal 12#s of lift. To remain neutrally buoyant, the diver must now remove 6#s of gas from the BC.
It’s definitely possible to manage the extra 4#s of gas. However, it requires more management and more diligence. For new divers, this extra 4#s of gas is additional work that is not necessary and only adds to make diving more difficult.
Requiring less weight the more I dive
As you gain experience, you shed add’l weight cause you improve your breath control, your body movement and buoyancy.
In addition, you’re be more effective in eliminating gas from your BC. Trapped gas or inefficient purging is one of the reasons that new divers need to carry more weight.