STA Weight with 7mm?

[cozumelkeith]

Hey All,
Posted this on DIRx, figured I'd give here a try as well...

Hey Guys
Recently ordered an STA weight (6lbs) after discussing weighting options with an LDS. Im a little concerned now after crunching some numbers that using the STA weight with a stainless backplate and 7mm might leave me with too much non ditchable weight.

Taking some numbers from the GUE Rec 1 workbook, at 30m with a full AL80:

Regs: -1.4kg
Tank: -1.8kg
Stainless BP: -2.7kg
STA Weight: -2.7kg

For a total of -8.6kg non ditchable weight.

With a 7mm I'm looking at about 2.7kg of lift at 30m, which gives me a buoyancy of -5.9kg. (Although I'll likely be wearing a hooded vest as well, so positive buoyancy from the suit might be a little more than 2.7kg).

Id be using my ACB pockets for the ditchable weight needed, but I am wondering, in your opinion, would using the STA weight with the setup I am describing here leave me unacceptably negative in the event of a wing failure at depth with full tank? I want to get as much weight off my belt as possible to facilitate trim, but wondering if maybe trim weights on cam straps with one or two pounds might be a better/safer way to go...

Thanks in advance for your help!

-Keith

 

[aquaregia]

I would also be concerned with those numbers. Are you sure an AL80 is -1.8kg full? Most sources I see say -1.4lbs salt water, which is only 0.6kg. Going from -5.9kg to -4.7kg might make a difference.

Try it and see if you can swim it up?

 

[cozumelkeith]

Hmm, yeah when I checked on pre-2009 Luxfer AL80s (what I have) says -1.4lbs (-.6kg)... Wonder if this is an error in the workbook?

 

[Kern]

Hmm, yeah when I checked on pre-2009 Luxfer AL80s (what I have) says -1.4lbs (-.6kg)... Wonder if this is an error in the workbook?

Al S080 luxfer is -1.7lb full & 4.2lb empty.

L6X® aluminum cylinder specifications - Luxfer: Setting The Standard Worldwide

The older spec is -1.4 full & 4.4 empty. (See attachment.)

I might question your buoyancy figure for the 7mm wet suit.