Drysuit weight approximation formula

[Rafael]

I'm a 200# guy, tri-lam drysuit, polar 300 undergarments.
when using steel 120's i add 22# of weight, on salt water.
10# on BC, 8# on belt and 4# ankle weights, and the steel thanks make up for about 6#, so the formula does apply for me too.

I just came back from Mexico where i did my Caverns specialty and while there i was using a 3mm in fresh water with AL 80's, 6# where enough to sink.

Dive safe.

 

[The Kraken]

I'm with Jonnythan on this one.

There seem to be too many variables in dry suit diving to come up with a patent formula to address the weight issue.

Here's my formula:

(Dry suit + undies + gear) - air to 500 psi / pool

the K

 

[dannobee]

It will get most divers close enough to do a pool check.

How close does it come for you?

 

[jonnythan]

It will get most divers close enough to do a pool check.

How close does it come for you?

It's off by about 5 lbs for me.

 

[dannobee]

Heavy or light? Are your unders thicker than 200 gm? Is your tank steel instead of an AL80? Salt water?

Bottom line is that it's better than no guess at all, and frequently comes close. You could always put a couple of extra pounds on your student and not have him blow through the safety because he's too light.

 

[RPanick]

Salt water or fresh? Shell suit or Neoprene? The rule of thumb is 10% of body weight + 5lbs with lightweight unders and a shell suit. Add 5 lbs more if the drysuit's neoprene. Compressed/crushed neoprene, maybe 2 lbs instead of adding 5. Add a couple of pounds if you're diving salt water. Obviously, do a pool check to confirm before doing a real dive.

The rule of thumb also suggests that you weigh 120 lbs (5% of body weight for a 3mm suit), so take that for what it's worth.

For me the formula doesn't even come close, with a shell and lightweight unders, I should be 33 lbs with the formula, I come in at 16 lbs when diving. Okay, I'm fat I admit it, I also sink in fresh water.

The pool is a nice theory, but reality is the water is too warm to find out what works. Dress to be warm enough, find a nice safe shore entry and walk in, you can add weights until you sink.

Unfortunately my first dry suit dive was off a boat, I was just lucky I guessed pretty close to what I needed. If I had to do it again, I would go the quary and play with it in a nice controlled setting.

Here's a better rule that seems to be pretty close, at least for me. Start with the weight you would use if you were diving wet. By this I mean if you would be wearing a 6mm suit for the water temps, and need 24 lbs, start with that. Turns out looking back at my logs when I was diving wet that was actually pretty close.

 

[divad]

OK:
1. You are using 6 #s of weight (BP and hardware).
2. You are using an AL 80.
3. You are using a 3 mil wetsuit.
4. You switch to a trilaminate drysuit and 100 gm underwear, everything else stays the same.
5. How more weight do you start to experiment with? One thousand pounds? Ten
pounds? One hundred pounds?

 

[jonnythan]

100gram.. what? Thinsulate? Fleece? Something else?

I'd head to a pool with about 20lbs of small weights and start with an empty belt and a tank with 500psi. I'd slowly add weights until I could easily sink.

End of story.