Scuba Skill - Determining Proper Weighting

[@shane472]

Rather strange that no mention of the tank pressure is made. Generally, a buoyancy check is performed with 500psi to simulate what your tank pressure will be at the end of a dive. If you're performing the check at the start of a dive with a 3000psi tank, you need to add weight to compensate for the increased buoyancy of your tank as you use up air. Otherwise, you may struggle maintain your position during your safety stop.

[@seikibrian8641]

I agree that you need to add weight if you did your check with a full tank, but disagree with those who say you should do it with 500 PSI. Doing a buoyancy check at the END of a dive is rather pointless, and taking a depleted tank to a dive site along with a full one isn't practical for most divers. Instead, do the check with full tanks, and then add the appropriate weight to compensate for the change in buoyancy; that difference is listed somewhere for most types of tanks. For example, a standard Sherwood aluminum 80 goes from -1.4 pounds full to +3.4 pounds empty; a Sherwood aluminum 80 "compact neutral" is -5.9 pounds full, and -1.4 empty; etc.

[@davidsantiago2856]

How much weight is typical to compensate the tank at 500psi at the end of a dive? is about 5lbs for the tank itself?

[@dannygjk]

Yeah...at the end of the dive if you have about 500 PSI left from 3,000 it will mean a gain in buoyancy of about 5 lbs. So maybe achieve neutral buoyancy, (with a full tank), while just below the surface and then add 2 lbs so that making a safety stop is easier, (if you have a line to hold ok but not all dives are that ideal). However it also depends on much suit you are wearing, from just a 2 mm 'T-shirt' to a full head to toe 8 mm suit. With a full cold water suit you will lose quite a bit of buoyancy even at about 30 feet from compression of the suit so then skip the extra 2 lbs.

[@ftfisher4x4]

I've always heard that this test should be done with 500psi of air. The goal is to not be under weight and positively buoyant at the end of the dive.

[@Aerosnapper]

This video is misleading. It makes no mention of the state of the tank, near empty or full. Nor does it provide any consideration of the weight of air consumed during a dive. This will vary significantly with different sizes and materials of tank.

[@seikibrian8641]

It's a two-minute video; just an overview. The details come from your instructor, as this video is not intended to replace formal scuba instruction.

[@YouTube_user3333]

I’m sick of seeing this misinformation. It depends on if your tank is aluminium or steel. It’s also meant to be done at the end of your dive, with 50 bar or 500psi in your tank. If you can’t maintain 3-5 metres (15-25ft) for your safety stop, this will be the issue.

[@rsauder]

BAD instruction for the below reasons. The tank needs to be close to what you'd have at the end of your dive, say 500lbs.

[@luxuryplaster1103]

it suppose your thank have to be fill all the way

[@justinbarber4567]

Terrible