How Much Weight Do I Need? The End-of-Dive Weight Check

Overweighting is the most common buoyancy problem in recreational diving, and the easiest to fix. Most divers were weighted once, in their first course, with a rental suit and a guess, and have carried the same lead ever since.

The fix is a five-minute check at the end of a dive.

How much weight do you actually need?

Enough to stay at a shallow stop at the end of the dive, with a nearly empty cylinder and no air in your wing. No more.

At the end of the dive, your cylinder is at its lightest, your wetsuit is at its thickest near the surface, and you're at the point where staying down matters most: the last stops before the surface. If you can hold those stops with the wing empty, you aren't underweighted. Any lead beyond that is extra weight you carry for the whole dive.

How do you do the end-of-dive weight check?

UTD runs this check at the end of training dives, at about 10 feet with roughly 500 psi left in an aluminum 80.

1. End a normal dive and ascend to your last stop, about 10 feet.
2. Use the planned near-empty-cylinder condition. About 500 psi in an AL80 is a reference condition, not a reason to consume emergency gas or extend a dive. Arrange the check with your instructor while retaining the gas needed to finish safely.
3. Empty your wing completely. If you're in a drysuit, keep only the gas you need to avoid squeeze.
4. Breathe normally and stay still. No kicking, no sculling, no big breaths.
5. Watch what happens. If you hold the stop with a normal breath, your weighting is right. If you sink, plan to reduce ballast for the next check. If you cannot stay down, reassess the setup before adding ballast. Have an instructor manage any in-water adjustment so you do not lose control.
6. Adjust in small steps and repeat on the next dive.
7. Write it down: suit, undergarments, cylinder, plate, water and the weight that worked.

Do it with a teammate or instructor close by and a plan for the ascent, and keep it to a calm, shallow stop.

Why does the cylinder matter so much?

Because gas has weight. An aluminum 80 holds about 77 cubic feet of gas at 3,000 psi, and that gas weighs roughly 6 pounds. As you breathe it, the cylinder gets lighter, and an aluminum 80 ends the dive buoyant.

At the start of the dive, your wing simply carries the weight of the gas you haven't breathed yet. That's why you weight for the end, not the beginning.

Steel-cylinder buoyancy varies by model and remaining pressure; some are neutral or positive near empty. Check the actual cylinder data and redo the weighting assessment. Gardner does not pair steel cylinders with wetsuits. UTD's general steel-doubles rule calls for a balanced exposure system such as a drysuit, except for steel cylinders neutral or positive at 500 psi/35 bar.

What else changes how much weight you need?

Charts that base weight on body weight or suit thickness are a reasonable place to start. They can't account for your body, your suit's age or your rig, so treat them as a first guess and let the weight check give you the answer.

Is the weight check the whole story?

No. It tells you that you aren't underweighted at the end of the dive. It doesn't tell you whether your rig is balanced at the start, when the cylinder is full and your suit is compressed at depth. If your wing failed then, could you manage the rig?

That question is the balanced rig, and it deserves its own check with your instructor. See What Is a Balanced Rig.

Where should the weight go?

Where you carry it changes your trim. Keep heavy items close to your center and adjust body position and ballast together. If your feet sink or your head tips down, see Horizontal Trim.

Get it checked in the water

Weighting, balanced rigs and the end-of-dive weight check are covered early in Essentials of Recreational Diving, with your own suit and rig. For the full picture of buoyancy, from weighting to breathing, read How to Master Scuba Buoyancy.