Weight check

A standard weight check begins with the diver wearing all their intended dive gear, including their exposure suit (wetsuit or drysuit) and a full cylinder. They enter the water and, at the surface, fully deflate their BCD. While holding a normal breath (not hyperventilating or holding excess air), the diver should ideally float at eye level, with the water breaking around their mask. If they sink, they are likely over-weighted; if they float too high, they are under-weighted.

The next step is to slowly exhale. With a full exhalation, the diver should gently and slowly descend. This confirms they have enough weight to start a descent without excessive effort. Once underwater, often in shallow water (2-3 metres / 6-10 feet), the diver will perform a critical part of the check: hovering at approximately 50% tank pressure. A diver's buoyancy changes throughout a dive as air is consumed from the cylinder, making them lighter.

To confirm correct weighting, the diver descends to a shallow depth, inflates their BCD to neutral buoyancy, and then consumes air until their cylinder is at approximately half full. At this point, with an empty BCD, they should still be able to maintain neutral buoyancy by holding a normal breath. If they float up, they need more weight; if they sink, they have too much. The goal is to be able to hover effortlessly at this 50% tank pressure point with an empty BCD.

For liveaboard divers, a proper weight check at the beginning of the trip is crucial, as conditions and gear can differ from their usual diving. Divers might be using rental equipment, different cylinder materials (e.g., aluminium instead of steel), or be diving in water with different salinity. Tropical liveaboards typically operate in saltwater, which requires more weight than freshwater diving.

Many liveaboards offer aluminium cylinders, which become significantly more buoyant as air is consumed compared to steel cylinders. This means that a weight check performed with a full cylinder might result in adequate weighting for the initial part of the dive, but the diver could become excessively buoyant towards the end, especially during the safety stop. Liveaboard dive guides are experienced in helping divers fine-tune their weighting to account for these changes.

Taking the time to do an accurate weight check early in the trip, possibly during the check dive, ensures that you are perfectly weighted for the majority of subsequent dives. This will enhance your comfort, reduce air consumption, improve your trim for easier movement and photography, and minimise the risk of accidental contact with delicate coral reefs, contributing to a more enjoyable and environmentally responsible liveaboard experience.

Myth: More weight is always safer, especially for new divers. Fact: Over-weighting can be dangerous and detrimental. It leads to poor buoyancy control, higher air consumption, difficulty maintaining trim, and can result in uncontrollable descents, making safety stops challenging and increasing the risk of reef damage. Proper weighting, not excessive weighting, is key for safety.

Myth: My weighting is set for life once I've done it. Fact: Weighting needs to be re-evaluated whenever there are significant changes to your gear (e.g., new wetsuit, different cylinder type), your dive environment (freshwater vs. saltwater), or your body composition. Even a slight change in exposure suit thickness or a new piece of equipment can alter your buoyancy.

Myth: You should use enough weight to sink immediately when you exhale. Fact: While exhaling should cause a slow descent, an immediate rapid descent often indicates over-weighting. The goal is a controlled, gentle descent after a full exhale, allowing for fine-tuning with BCD inflation as needed. Rapid sinking can stress a diver and make clearing ears more difficult.

Myth: The amount of weight I use is a sign of my diving skill. Fact: The amount of weight a diver uses is highly individual and depends on numerous factors, including body fat, exposure suit, gear, and water type. Using the correct amount of weight for neutral buoyancy is a sign of good diving practice and understanding of physics, not the specific number on the weight belt.