Being over-weighted is one of the most common mistakes that divers make. It's easy to assume that having an extra kilo or two will not make much difference, but it really does. Every extra kilo of weight you carry requires an extra litre of air in your BCD to compensate. This increases the size of your BCD and creates more drag which in turn will require more effort from you to move through the water. This now means you expend more energy and use more air - exactly the opposite of what you want when you dive.
So how to determine the correct amount of weight to carry? During the PADI Open Water Course we learn to adjust for proper weighting as follows – carry enough weight to float at eye level at the surface with an empty BCD while holding a normal breath. If you can do this with 50 bar in your tank your weighting should be about right. This is a good rule of thumb but maybe there is more to consider?
The time you need to have enough weight to stay underwater comfortably is at the end of your dive when you are at 5m making your safety stop. If you are perfectly neutral at this point of your dive then you will be slightly positively buoyant during your final ascent, but this is compensated by the fact you can make your lungs slightly smaller during the ascent and it is good practice to be exhaling while you ascend anyway.
So here is a great way to calculate the correct weighting for yourself on your next dive. Carry your normal number of weights but leave one of them inside the pocket of your BCD. At the end of the dive when your tank is at 50 bar, make your safety stop near a buoyline just to be safe. When ready, pass the weight to your buddy and empty your BCD. If you can hover comfortably without moving your hands or fins, then you now are wearing the correct amount of weights.
Of course there are times when it makes sense to carry extra weight, such as when there is surge, if you haven't dived in a while or if you might need to pass an extra weight to a buddy. But in general it is best to have the exact weighting as this will give you much better buoyancy control and will dramatically improve your air consumption.
If you wish to find out more ways to improve your diving skills and use less air, check out the PADI Peak Performance Buoyancy Specialty Course. Not only will it bring you closer to diving like a pro, but you also get to make 2 dives at some of the best dive sites in Thailand. A great time to take this course is when you haven't dived for a while and wish to get back in the water. Not only will you refresh the diving skills you previously learned, but you will amaze yourself with how effortless diving can be when you do it properly.
Plus, better buoyancy control helps protect you and also our fragile corals, so you can help yourself and also the environment :)
Plus, better buoyancy control helps protect you and also our fragile corals, so you can help yourself and also the environment :)