Before you explore the oceans deep with a scuba dive session, you need to make sure you can cope with and counter the buoyant force. The idea is to sink below the surface, which ordinarily is not a particularly hard thing.
That is until you strap on a whole host of different diving equipment. This is why it pays to be familiar with different types of dive weights and complete a pre-dive weight check before ascending into your next adventure.
How to Complete a Pre-Dive Weight Check
When you are looking at scuba diving weight belts or if you are finding it difficult choosing either weight belts or an integrated weight system, remember the goal of all your efforts, to remain buoyant.
If you are struggling to understand the term buoyancy, it’s the natural force that makes objects float in water. Further to getting to the point of sinking below the surface you can then adjust things with your equipment and gear to ensure you maintain and achieve neutral buoyancy. This is called a pre-dive weight check. Here’s how it works.
Predive Weight Check
Although it may seem tricky, it’s quite easy determining whether you have enough or too much weight for a dive. You need to use a body of water that reaches at least your chest level or higher. Ideally, a swimming pool or by the boat is your best bet. Then you can have additional weights close to hand.
Ask for help from your diving buddy or an instructor or friend to help with handing each additional weight as you need them while making alterations. You need to make sure you wear the diving equipment you are going to wear on your dives, including fins, mask, exposure protection, BC, tank, the weight you estimate you need and those accessories you are going to take with you too.
To start, have your BC fully inflated and the regulator and mask in the correct position. Get into an almost vertical position and if you are in shallow water that allows you to stand, lift your feet a little from the bottom of the pool and then vent all the air out of your BC while taking a full, but a normal breath. Stop breathing for a moment and work at staying motionless.
If you have the correct amount of weight to achieve neutral buoyancy, then you should start to float with the water around between your eye-level and hairlines level. Once you finally exhale completely, you will, if everything’s gone correctly, start to submerge into the water.
If, though you find your mask has not submerged partially while conducting the first weight test, you are probably underweighted and should start adding weights one at a time. Do this until you start to float as illustrated above.
On the other hand, if you started to be submerged almost immediately, you are probably overweighted and should remove around a 1lb at a time until you are floating with the water at eye level. Here’s a short visual video clip on how to complete a pre-dive weight check.
If you dive at a few different locations, you should make a note of the weight you require at each to achieve neutral buoyancy. You can use your logbook for this.
What Has an Effect on Your Buoyancy?
Well, this question is rather simple – just about everything and anything has an effect on your buoyancy.
Whether it’s the weight worn, the volume of air already breathed, the type of exposure gear and equipment you are using, your own body makeup and whether the water you are diving in is fresh or salty.
Why Neutral Buoyancy is Vital
Enjoyable diving experiences are only possible if you have a proper and balanced weighting in place. If you don’t have enough weight, for example, you could find that you are unable to descend and will just stay at the same depth. Something that can really put a dampener on the whole scuba diving experience.
You then have the problem too of when you need to initiate a safety stop while in shallower water because your tank will be much lighter towards the end of your dive than it was at the start.
Taking more weight than is necessary is also problematic, as you could too easily lose the control you need over your rate of descent. This increases the risk of barotrauma or mask squeeze, as well as the issue of you diving further down than you had originally intended.
It also means your BC needs more air added to maintain neutral buoyancy. Thanks to the extra air present in the BC, the torso will rise more than normal and when you have weights on your waist, it makes you swim at a diagonal rather than in a more pleasant fashion.
Weighting is central to achieving and maintaining neutral buoyancy. By far the best way to figure out the proper amount of weights you need is long before you get into the water. That’s why it’s so important to carry out a weight check as part of your predive routine.