How much weight to rent before you arrive at a dive shop
Summary
Dive shop rental forms ask how much weight a diver needs before they have seen the water, the suit, or the tank. The answer can be calculated from four things knowable in advance: body weight, the exposure suit being rented, salt or fresh water, and tank material. The baseline is roughly 10 percent of body weight, adjusted for those inputs. The most useful thing to write on the form is the number together with its assumptions, because that lets the shop correct it with knowledge of their own gear before packing. A diver who logs weight on every dive turns this question into a lookup.
The four inputs to work out in advance
- Body weight: the baseline is approximately 10 percent of it in lead, adjusted by the factors below.
- Exposure suit: ask the operation, or check the water temperature for the month of travel. Most warm-water operations supply 3mm suits.
- Water type: ocean diving requires about 4–6 lb (2–3 kg) more lead than the same dive in fresh water.
- Tank: nearly all warm-water operations use aluminum 80s. Cold-water operations often use steel, which changes the figure by 4–6 lb.
What to write on the form
A bare number is less useful than a number with its assumptions attached. A complete answer looks like: "About 14 lb / 6 kg — based on 160 lb, 3mm full suit, salt water, aluminum 80. Happy to adjust at the checkout dive." If the operation's suits run thicker, or they are supplying steel tanks, they can correct the figure before packing the crate rather than searching for weights on a moving boat.
If the number is genuinely unknown
State that, and supply what is known: body weight, rough experience level, and whether the diver tends to run heavy or light. A dive operation would rather receive "I am 160 lb, last dived a year ago in the Caribbean, I think I carried around 12 lb" than a confident figure that proves wrong. Asking them to bring a couple of pounds either side costs nothing.
Why the question is hard only once
The rental weight question is difficult the first time because the answer was not recorded the previous time. Logging the lead, the suit, the tank, and the water type on every dive, together with a one-line verdict on whether it was correct, converts the form from a puzzle into a lookup. The SCUBAzen logbook is free and searchable, and its paperwork generator produces a rental form with the diver's sizes and weight already filled in.
Frequently asked questions
How do I know how much weight to rent before a dive trip?
Calculate it from four things you can know before travelling: your body weight, the exposure suit you will be renting, whether the water is salt or fresh, and the tank material. Roughly 10% of body weight is the baseline, adjusted for those inputs. Give the shop the number along with the assumptions it is based on.
What should I write on a dive shop rental form for weight?
Write the number and its assumptions, for example: about 14 lb / 6 kg, based on 160 lb body weight, 3mm full suit, salt water, aluminum 80, happy to adjust at the checkout dive. Assumptions let the shop correct the figure using what they know about their own suits and tanks before they pack the gear.
What if I genuinely do not know how much weight I need?
Tell the shop what you do know: your body weight, your rough experience level, and whether you tend to run heavy or light. A dive operation would rather hear an honest estimate with context than a confident number that turns out to be wrong, and can bring a couple of pounds either side.