Some Divers Really Need to Drop a Few Pounds

We've all been there. Traveling solo, you get paired with a diver you don't know. All is well until you note he's wearing only a thin shorty and going in for the check-out dive with 30 pounds of weights. I remember well, questioning such a person if all that lead was necessary before jumping from the boat, only to find him flailing around on the sand 33 feet below me with his BCD fully inflated.

Why do we need weights? The human body is more or less neutrally buoyant. The weights counteract the buoyancy in our equipment, mainly our wetsuits. If you we start neutrally buoyant at the surface (allowing extra lead for the weight of gas we will consume during the dive), you we should only need to add air to our buoyancy compensating device to compensate for the loss of displacement of our wetsuit as it gets compressed while we go deeper. That doesn't seem to stop some divers from going in over-weighted.

Remember that buoyancy test? At the surface, you should have your eyes above the water when you breathe in, and sink only when you exhale. Add weight to compensate for the air you'll use during the dive. Eighty cubic feet of air weighs about seven pounds, but hopefully you won't use it all. (You should come back with some air left in your tank.)

When it comes to over-weighting, drysuit divers are among the worst culprits. I often hear one say that she only puts air in her suit to take off the squeeze, then uses the BCD for buoyancy control. The auto-dump valve of a drysuit used to be called a constant-volume dump. The clue is in the name. If the drysuit diver is neutrally buoyant at the start of the dive, she will need only to put air in the suit to compensate for its compression as she goes deeper. Maintaining the suit at constant volume keeps it at constant buoyancy because it displaces the same amount of water. The BCD becomes redundant. If a single-tank drysuit diver needs to use her BCD as well, it's probably a sign she's over-weighted.

Some divers say "why worry about too much weight -- you can always put extra air in the BCD to compensate, right?" Besides using more energy and having your tank run out quicker, Ken Kurtis of Reef Seekers Dive Company (Beverly Hills, CA) points out that rescuing a diver in distress is more difficult if he is overweighted. The deeper the rescue that has to be made, at, the riskier it becomes, with the degree of difficulty increasing exponentially.

So it's worth your effort to gently encourage those over-weighted divers you see to shed a few pounds and have a better and safer dive - for everyone.

- - John Bantin