Weight Distribution For Wreck Diving
When using a BC [buoyancy compensator] with an integrated weight system, is it better to put more weight in the upper back weight pockets? Especially for wreck diving where losing a front weight pouch that could cause a rapid ascent.
There are actually two different questions here, so let's address each separately. Clearly, redistributing weight will provide better trim. That's the whole purpose of doing it, and why many BC manufacturers now put pockets for small weights in the rear portions of the devices. Some have found success in simple tricks like clipping an ankle weight around the tank valve, or securing small weights to the tank itself. Anything that will shift the center of buoyancy to the point where you can achieve a more comfortable horizontal swimming position is likely to reduce your level of exertion and, therefore, your air consumption. It can also go a long way in reducing anxiety.
The second issue — the danger of a rapid ascent — is another matter. The risk of an abrupt buoyant ascent resulting from the loss of a weight belt, unless you're wearing an overinflated dry suit or you're in extremely shallow water, is largely myth. In your case, especially, even if you lost a front weight pocket inadvertently, you'll still have the remaining ballast in the rear compartments. As many divers come to learn, unlike in a swimming pool, when you ditch your weights at depth you almost always have to initiate an ascent by kicking before the effect of positive buoyancy takes over. Concentrate on weight redistribution for better trim, and don't be too concerned about the rapid ascent consideration.