This is a tough question every diver faces from time to time. Although only a buoyancy check precisely determines the proper amount of weight needed, here are some basic weight guidelines that’ll get you started. These guidelines are based on individuals of average build, diving in salt water. Lean individuals or individuals diving in fresh water may need less weight, heavy individuals may need more.
Basic Guidelines:
Exposure Suit Type and Weight to Begin With
1. Swimsuit or dive skin 1 – 4 lb.
2. Thin (3 mm) one-piece 5% of your body weight
wet suits – shorties or jump suits
3. Medium-thickness (5mm), 10% of your body weight
two-piece wet suit
4. Cold-water (7mm), two-piece 10% of your body weight,
wet suit with hood and boots plus 3 – 5 lb.
Conversion Estimates for Salt or Fresh Water
Convert from salt water to fresh water (or vice versa) using the following
estimates.
Weight to (+)Add (Fresh Water to Salt Water) or (-)Subtract (Salt Water to Fresh Water)
Body Weight
100 – 125 lb. 4 lb.
126 – 155 lb. 5 lb.
156 – 186 lb. 6 lb.
187 – 217 lb. 7 lb.
Estimating Weight Change Due to Air Consumption
Depending on the type of tank you use, it can become 3-5 lb. more buoyant by the end of your dive. The popular aluminum 80 tank will become approximately 5 lb. more buoyant. To compensate for this increased buoyancy near the end of your dive, you may need to add some weight beyond the basic guidelines above. Additional weight, beyond the guidelines may not be needed for some types of steel tanks.
Using the Estimates – Two Examples
1. A diver weighing 155 lb. buys a medium thickness, two-piece 5mm wet suit. Using the estimates above, he decides to begin with 15 lb. in salt water or 10 lb. in fresh water. He plans on using an aluminum 80 cubic foot tank, so he adds 5 lb. of lead to his weight system. To begin his buoyancy check he enters the water with an estimated 20 lb. in salt water or 15 lb. in fresh water.
2. A diver weighing 188 lb. travels to a resort, warm-water ocean destination where he decides to dive using nonbuoyant dive skins. Using the estimates above, he decides to begin with 4 lb. Since he is a little pudgy, he decides to add an additional 1 lb. The divemaster informs him that the steel tanks supplied by the resort are neutrally buoyant at the end of the dive. With this information he decides conduct his buoyancy check at the beginning of his first dive with a total of 5 lb.
Remember that this is a starting point and a general guideline. You should conduct your own buoyancy checks with an empty aluminum 80 (250-500 psi) to see what you really need.
Have fun, and safe diving!
