Why correct weighting in scuba diving is a matter of safety. How to choose the right amount of weights for your dives

When we think of scuba safety, our minds immediately go to technical gear, dive computers, and dive profile planning. All too often, however, even the most experienced divers overlook a crucial element: proper weight management. Yet, correct weighting is the cornerstone of a safe, comfortable, and efficient dive.

This is a stage every diver goes through, from their first days as a novice: you start your theory lessons and you’re soon confronted with the divers’ boogeyman, the specter told to young divers sitting around campfires on summer nights while owls screech and fireflies swirl in the air: the “runaway ascent,” the loss of buoyancy control that sends divers shooting towards the surface, jeopardizing their lungs and causing countless tiny, hostile nitrogen bubbles to explode in their blood vessels and tissues. And so, everyone, acutely aware of their inexperience and shaky buoyancy control, sooner or later thinks: “I don’t want to risk it; better to carry a few extra kilos on my weight belt than end up as another cross in the cemetery.” And that’s how you get novice divers, laden with anvils strapped around their waists and BCDs inflated like party balloons, clumsily simulating artificial pufferfish in the ocean depths.

But over-weighting, even out of presumed caution, is a serious mistake that leads to buoyancy problems, excessive air consumption, and unnecessary physical effort during the dive.

Let’s see why having the correct weight is essential, and how to achieve it.

Weighting: an art that makes the difference

Learning to master your weighting isn’t just about better buoyancy—it can literally save your life in an emergency. A concrete example? A BCD failure: if you’re over-weighted, you might be unable to ascend or maintain a safe depth, and your only option will be to ditch your weight belt—risking a dangerous runaway ascent, precisely the hazard you tried to avoid by strapping on enough lead to resemble a Maginot Line artillery battery.

The effects of excessive weighting

Carrying more weight than necessary complicates buoyancy control: it increases physical effort, speeds up air consumption, reduces hydrodynamics, and makes every dive more tiring and less enjoyable. But above all, in emergencies like a BCD malfunction, excess weight can become dangerous, compromising your ability to ascend in a controlled way. The purpose of weighting is simple: add the minimum amount of weight needed for a controlled descent and to manage safety stops or surface emergencies—even with malfunctioning gear. During the dive itself, at depth, the pressure of the water column will keep you down.

A quick anecdote: the author, during a dive on the Thistlegorm wreck in the Red Sea, spent an hour wondering why their buoyancy felt different that day, only to realize at the end of the dive, while removing their gear, that they’d done the entire dive… without a weight belt. Of course, the idea that I’d been so absent-minded as to dive without my belt never crossed my mind during the dive itself. But at the Thistlegorm, partly due to the current, partly to low visibility, the descent and ascent are done by pulling yourself along the line anchoring the boat to the wreck; since I didn’t need the belt for the descent or ascent, and the dive itself takes place almost entirely at 30 meters deep, I didn’t miss the belt, even if I noticed some oddities in my buoyancy—pressure alone kept me down. I can laugh about it now because everything went well, but things could have taken a bad turn: don’t try this at home! The point of this anecdote is to show that your weight belt plays its most important role during descent and ascent; at depth, weight is relatively unnecessary, so you should avoid carrying even a kilo too much.

How to calculate correct weighting

The ideal weight is calculated by knowing the buoyancy characteristics of every piece of your equipment, including:

• the wetsuit (positive buoyancy, especially with thick neoprene or drysuits),

• the BCD,

• the tank (negative buoyancy, varying with gas consumption; don’t forget the tank becomes lighter when nearly empty),

• any plates or accessories,

• your own body; if, like most divers, you carry extra body fat, Archimedes’ principle will give you additional buoyancy.

A practical approach is to sum the positive (wetsuit, BCD) and negative (full tank, plates) buoyancies, then determine the initial weight required to offset the difference. But beware: during the dive you’ll use gas, your tank will become lighter, and your buoyancy will shift. To account for this, you should add 1.5–2 kg depending on your tank size and gas consumption.

The perfect weighting check

The most effective way to find your perfect weighting is to run a careful check at the end of your dive, with your tank nearly empty (around 50 bar), since that’s when you’ll be lightest. Proceed as follows:

• Stop at a depth of 3–5 meters.

• Empty your BCD completely.

• Hold your lungs at mid-capacity (about 50% full).

• If you stay stable without rising or sinking, your weighting is perfect.

• If you sink when exhaling or rise slowly when inhaling → you’re perfectly weighted.

• If you can’t control your buoyancy with your breath alone → you need to adjust your weighting.

Remember: even 1 kg too much can force you to stay neutral only by keeping your lungs completely full, reducing your margin for a safe ascent. With 2 kg excess, you could lose control and sink uncontrollably, unable to counteract descent even by breathing.

Practical tips to avoid mistakes

✅ Check your weighting every time you change equipment (wetsuit, tank, BCD).

✅ Record your settings in your logbook: they’ll be a valuable reference for future dives.

✅ Never skip these checks, even after years of experience—safety is built on good habits.

Conclusion: Weight management isn’t a minor detail but an essential skill for every diver who wants to dive safely and in maximum comfort. Taking the time to find the correct weighting reduces real risks, improves your diving experience, conserves air, avoids unnecessary strain on your back, makes gear lighter topside (for example on a rocking boat or during rocky shore entries), and above all prepares you to handle emergencies more calmly.