Most divers are overweighed, partly from the fact that their benchmark is the amount of weight they used when doing their Open Water course and more often due to their decision to add more weight after having a dive where they struggled to descend.
We are not all the same and different tissues have a different specific gravity, fatty tissues less than 1 and muscle and bone around 1.8-1.9 therefore not all 80 kg divers will wear the same weight.
Wetsuits, boots, gloves, mask volume, hoodies all have different buoyancy characteristics just as changing from a 10 litre cylinder to a 12 litre cylinder will also affect your buoyancy. As your comfort level in the ocean increases your breathing rate improves, your control over the inflator button improves (i.e. small bursts). All these factors contribute to achieving the real weight you require.
Tank weights are often used to ensure a diver is ”heavy” saving the instructor or divemaster the hassle of a buoyant diver floating on the surface whilst the rest of his divers are descending to unknown depths. Tank weights are promoted as being the reason a diver is balanced. Ankle weights are also often added to girls’ ankles as they are ”too light”. A huge factor in this is the material used in their fins: some cheap fins float like corks. I don’t like tank weights because if you are at 25 metres and run out of air you will be unable to ditch all your weights. A well trained diver will not be over weighted, will not run out of air at 25 metrees or have any other mishap… However correct weighting, proper training and a competent diver in the correct gear all go hand in hand. Mess with just one of these aspects and mishaps do happen.
If you think you are correctly weighted, lie in 5 metres of water, take your weight belt off and hold it in your lap. Slowly remove one weight at a time: you will be surprised at how little weight you need to stay at the bottom. Another option is to place your weight belt on the bottom, hold it tightly and move your arms up and down the length of your body until you are perfectly horizontal. If you find you need all your weight on your chest..then look at a BC with integrated weight pockets. Moving your cylinder up and down in your BC strap also helps find the perfect balance. Remember adding a shorty wetsuit and a rash vest to keep you warm add to the buoyancy of your chest area. A hoodie that fills with air also affects your profile.
