In an earlier training tip, we covered the importance of mastering your buoyancy. An important piece of that puzzle is your weight system, as proper dive weights can make or break a dive. Excessive weight will make you slower and less agile, and you’ll use more air during your dive. Too little weight and you’ll spend the dive (especially the latter part of it) struggling to stay submerged.
Evaluating your dive weights
We all know the standard buoyancy test: before a dive, get in the water and deflate your BCD. After doing so, you should float with the waterline at about eye level and bob gently up and down as you breathe. As you exhale beyond your normal breath, you should start to descend. If you sink while breathing normally, you’re too heavy. And if you cannot descend, no matter how much you exhale, you’re too light.
To get an even better impression of your weighting, use your safety stop. When you reach approximately 50 bars (725 psi) of air remaining in your tank, you should be able to completely deflate your BCD and stay at your designated depth of about 15 feet, hovering there using nothing but your breath. If you’re unable to do this without sinking when you deflate your BCD, you’re too heavy. If you’re not able to maintain 15 feet of depth, but find yourself surfacing even with an empty BCD, you’re too light. Most divers find that they are too heavy.
Adjusting your dive weights
The trick is to remove the correct amount of weight if you’re too heavy, or to add just enough if you’re too light. If you dive in tropical conditions, you may find that you’re too heavy even with minimal or no weight (this happens to me). The solution, then, is to switch your tank from steel to aluminum (if using steel), or to choose a smaller tank, provided it still meets your gas needs. If none of this makes you light enough, something that can happen for divers with very small frames, and/or when diving with minimal insulation, the only thing to do is to adjust with the BCD.
The trickiest part of adjusting your weighting is removing weight during a dive. If you have a helpful buddy, he or she might agree to hold a pound or two for you if you find yourself too heavy. As long as you’re adjusting your weight, always bring a logbook to make note of whether it was too little or too much. Note as well the conditions of your dive, if you change environments frequently — saltwater or fresh, exposure protection, type of tank, etc. This way, you’ll not only be able to make the adjustments before your next dive, but also adjust for dives in a variety of scenarios. As you gain experience, you’ll start to get an idea of your weight needs with different configurations.
In any of these cases, unless you’ve done the safety-stop test, remember to add a pound or two to the weight setup you begin with to compensate for the air that has been emptied from the tank during the dive.