Drysuit weighting: how much lead to add, where to put it, and how to check it

Summary

A drysuit diver typically needs 4–8 lb (2–4 kg) more lead than the same diver in their thickest wetsuit, because the undergarment's insulating loft and trapped air add buoyancy that must be sunk. A common landing zone in cold salt water is about ten percent of body weight plus a couple of kilograms, but drysuit numbers spread more widely than wetsuit numbers, so the figure must be verified by a surface check and a near-empty-tank check at the safety stop. Weight belongs to the suit-plus-undergarment combination, not the suit alone, and carrying too much lead creates a large unstable air bubble inside the suit.

What actually floats

A drysuit shell on its own floats little. The buoyancy comes from what the shell keeps dry: the loft of the undergarments and the air trapped in and around them. That insulation is the purpose of the suit, and all of it must be sunk with lead. This is why there is no single drysuit number — the same shell over a thin fleece and over a heavyweight thermal undersuit are two different weighting problems, several pounds apart. Each combination of suit and undergarment has its own number.

Dialing it in, step by step

  1. Start from an estimate. Take the diver's 7mm wetsuit number for the same water and add 4–8 lb, toward the high end for thick undergarments. Without a 7mm reference, start near ten percent of body weight plus 4–6 lb in salt water, less in fresh.
  2. Surface check in full kit. Undergarments on, suit zipped and vented, tank on, BCD empty. Holding a normal breath should float the diver at eye level; a full exhale should start a slow descent.
  3. Add only enough suit air to relieve squeeze. On descent, small puffs into the suit stop the pinch. The BCD remains the buoyancy tool; the suit is insulation and comfort.
  4. Verify at the safety stop with a near-empty tank. The diver should hold 15 feet comfortably with 500–700 psi remaining. Adjust by one or two pounds per dive, one change at a time.
  5. Log the combination. Record the lead together with the undergarment, tank, and water type — "24 lb, heavyweight undersuit, steel 100, salt" is reusable for years.

The overweighting spiral

Drysuits punish excess lead more than wetsuits do. Extra lead requires extra air in the suit to stay neutral; a bigger bubble shifts with every trim change and migrates toward the boots when the diver goes head-down, producing instability that is usually blamed on the suit. The fix is almost always less lead, not ankle weights. A correctly weighted drysuit diver manages a small, calm bubble.

Weight placement

With a larger total, placement matters. Enough lead should stay in ditchable pockets to create real positive buoyancy in an emergency; the rest can spread across trim pockets, tank weights, or a harness until the diver holds flat trim without sculling. A steel tank carries several pounds of the ballast job by staying negatively buoyant through the dive, but fixed ballast should never grow so large that nothing can be dropped. Freshwater drysuit diving stacks the salt-to-fresh adjustment — about 4–6 lb less — on top of everything here.

Frequently asked questions

How much more weight does a drysuit need than a wetsuit?

Typically 4–8 lb (2–4 kg) more than the same diver needs in their thickest wetsuit in the same water, with the exact figure set by the undergarment. A common landing zone in cold salt water is about ten percent of body weight plus a couple of kilograms, verified by a buoyancy check.

What makes a drysuit buoyant — the suit or the undergarment?

Mostly the undergarment. The shell itself floats little; the buoyancy comes from the loft of the insulation and the air it traps. The same shell over a thin fleece and over a heavyweight undersuit are different weighting problems several pounds apart, so weight belongs to the suit-plus-undergarment combination.

What happens if a drysuit diver carries too much lead?

Extra lead requires extra air in the suit to stay neutral. The larger bubble shifts whenever trim changes, migrates toward the boots when head-down, and makes the diver unstable. Overweighted drysuit divers usually blame the suit, but reducing the lead shrinks the bubble and restores control.

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