Weight Up!

Though seemingly insignificant, weights are an important component of a dive setup that should not be overlooked.

- Marty McCafferty, EMT-P, DMT, and Patty Seery, MHS, DMT

Early in dive training, students learn that there are three elements involved in buoyancy control: the buoyancy compensator (BC), weights and lung volume. Although most divers are familiar with the need to be properly weighted, many do not understand all that it entails. Students and experienced divers alike make two common errors when it comes to weighting: diving while overweighted and failing to adjust the amount of weight used in response to changes in equipment and environment.

DON’T WORK TOO HARD

Improper weighting makes it harder to achieve neutral buoyancy. Many divers who wear too much weight do not even realise they are overweighted. The excess weight means that to achieve neutral buoyancy, the diver has to put more air into the BC bladders, which can create a more upright profile in the water. The upright position increases drag when swimming, causing the diver to expend more effort and consume more air. Underweighted divers can also become significantly fatigued while trying to stay down. In addition to increasing breathing-gas consumption, extra exertion can elevate decompression stress.

GET IT RIGHT

You may have heard a diver say, “This is how much weight I always use.” While field testing and prior experience can be useful, this statement shouldn’t be the endpoint of a dialogue about weighting. Proper weighting requires thought and practice, and the amount of weight worn is not fixed. Over the course of our lives, we experience change in muscle mass, body fat and physical fitness. Equipment, including wetsuits, wears out and gets replaced. Dive environments differ. All these factors affect buoyancy and require adjustments to the amount of weight used.