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.
- End a normal dive and ascend to your last stop, about 10 feet.
- Have about 500 psi left in an aluminum 80. Plan for it. Don't extend a dive to get there.
- Empty your wing completely. If you're in a drysuit, keep only the gas you need to avoid squeeze.
- Breathe normally and stay still. No kicking, no sculling, no big breaths.
- Watch what happens. If you hold the stop with a normal breath, your weighting is right. If you sink, you can take some lead off next time. If you can't stay down, you need a little more.
- Adjust in small steps and repeat on the next dive.
- 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 cylinders vary by model. Some stay negative when empty, some don't. Know yours, and redo the weight check when you change cylinders. UTD requires a balanced exposure system such as a drysuit with steel doubles, and in my classes steel never goes with a wetsuit.
What else changes how much weight you need?
| Factor | Effect |
|---|---|
| Exposure suit | Thicker wetsuits and drysuit undergarments need more lead |
| Salt or fresh water | Salt water is denser, so you float more and need more lead |
| Cylinder | Material, model and remaining gas all change buoyancy |
| Backplate | A steel plate carries ballast you'd otherwise wear on a belt |
| Your body | Body composition changes buoyancy as much as size does |
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.
Frequently asked questions
Why do the weight check at the end of the dive?
Because your cylinder is lightest then. An aluminum 80 gets about 6 pounds lighter as you breathe it down. If you can hold a shallow stop with a nearly empty tank, you aren't underweighted at the point where it matters most.
Does a steel backplate reduce how much lead I need?
It moves some of your ballast onto your back, but your total is about the same. You still keep some weight you can ditch.
How often should I redo the weight check?
Whenever anything changes: a new suit or undergarment, a different cylinder, fresh water instead of salt, or a new plate or wing. Log the result so you can start from it next time.
Is it safer to carry a few extra pounds?
No. Extra weight means more air in your wing, more effort to stay stable and more gas used. It also makes a wing failure harder to manage.
Related reading
How to Master Scuba Buoyancy: Weight, Trim, Breath
Good buoyancy comes from correct weighting, a balanced rig, horizontal trim and calm breathing, in that order. Here's how to fix each one.
Read articleDrysuit Buoyancy and Trim: Fixes for Floaty Feet
In a drysuit, gas moves to the highest point, often your feet. How to manage suit gas, weighting and trim, recover from floaty feet and dive dry in San Diego.
Read articleHow to Hover Without Using Your Hands
Sculling hands are a symptom of weighting, trim or breathing problems. Why hands creep in, how UTD scores buoyancy and drills to keep your hands still.
Read article