Almost Every Skill Problem in Diving Is a Weighting Problem Wearing a Disguise

Watch a group of recreational divers and you can usually rank them on one variable. Not depth, not certification, not how much equipment they own. Whether they are still.

A diver in control hangs in the water and barely moves. A diver who is not is finning constantly, drifting up and down, and touching things. The difference is almost never talent, and it is almost always weight.

The cascade

This is the mechanism, and once you see it you cannot unsee it.

A diver is overweighted, usually by three or four kilograms, usually because a shop guessed high on their first dive and nobody has revisited it since.

To offset that lead they carry more air in the buoyancy compensator. That air is a gas, so it compresses on descent and expands on ascent. The more of it you carry, the more violently your buoyancy swings with every change in depth, and the more constantly you are adding and dumping to stay level.

Fighting that swing means finning. Finning with a body angled head-up, which is what excess lead on a belt encourages, drives you upward, so you compensate by dumping more air, which makes you heavier, which needs more finning.

The results are a diver who is never still, breathes hard, uses far more gas than their buddy, cannot hold a safety stop in any swell, kicks the reef, and gets cold because they are working the whole dive.

Every one of those symptoms is usually treated as a separate skill deficiency. They are one problem.

The weight check, done properly

Almost everybody does this wrong, because they do it at the start of the dive with a full cylinder.

Do it at the end, with roughly 50 bar left. Empty the buoyancy compensator completely. Hold a normal breath. You should float at eye level. Exhale fully and you should begin to sink slowly.

The reason it has to be at the end is that a cylinder gets lighter as you breathe it. An aluminium 80, the commonest recreational cylinder, is negatively buoyant when full and becomes roughly two kilograms positively buoyant when nearly empty. If you weight yourself correctly for the start of the dive, you will be two kilograms light at exactly the moment you are trying to hold a safety stop at five metres with an almost empty tank. That is why safety stops feel impossible to so many people.