How Much Weight Do I Need?
Sounds familiar right? You just arrived at a beautiful dive site to explore, you’re gearing up and then the dive guide asks how much weight do you need? Hmm, what was it again, did I make a note in my logbook? Did I use a wet suit, dry suit, short or full-suit, salt water or freshwater (like the cenotes). It’s very common problem among us divers.
One the one hand, nobody wants to bring too much weight. You don’t want to sink like a rock nor have to compensate by overinflating your BCD. Resulting in more drag, more water resistance, since the surface breaking the water column is now increased and carrying unnecessary weight on the surface and in the water. Which means you use more energy and automatically will cost you more air.
On the other hand too light is also not an option. Carrying too little weight can jeopordize your safety stop (and deco stops). Especially in cenotes this is another argument why you should always have a balanced configuration, because in overhead diving you would risk ending up to the ceiling, keep on fin kicking down to hold your position, as your tank is becoming more empty.
The challenge lies in finding a balanced configuration. There are 3 ways of determining your weight: theoretical, beginner and technical way.
1. Theoretically you could bring all your gear separate to dunk it under the surface level, and put enough weight on it to offset the balance (becoming neutrally buoyant). Including yourself, empty tanks, wetsuit, BCD, etc. Sum the results of all the gear and what you need up to determine the weight you need. Although this is the most accurate way, it is very time-consuming and not really practical.
2. When you just started diving, you’ve probably been taught to float on eye-level holding a normal breath in the beginning of the dive. If you sink too fast you have to deduct weight and if can’t sink you probably have to add some weights. Problem is what is too fast?! Further if you would float on eye-level exhale and descent it is unlikely that you would be able to maintain your shallow stop with nearly empty tanks. As a rule of thumb for a standard aluminum 11 liter tank filled to 200 Bar (or 80 cft), you would have to add 3 kg (6,5 lbs) after floating on eye level holding a normal breath.
3. The last way is often used by technical divers. Starting in the shallows checking at the surface for enough lift. That means that you can easily float at the surface with full tank(s) at the beginning of the dive. And on the end of the dive with nearly empty tanks (30 – 50 Bar) you can hold your stop for a couple of minutes motionless at shallowest depth. But how much could be integrated? Well you should be able to swim to the surface with a BCD-failure at bottom depth with full tanks, if this is not possible a part of your weight needs to be ditchable (on weight belt or pockets) until you can make it safely to the surface.If it doesn’t feel right, probably there is something off. Once you have the right weights, you immediately feel the difference!
Having trouble determining how much weight you need, consider taking our Buoyancy specialist course.
