Info The "Ultimate" wing lift calculator :)

[cool_hardware52]

Tobin,

If my most buoyant suit is 30 lbs. and I am diving doubles why would I need a 94 lb. wing?

Bill

You don't. The largest doubles wing we offer is 57 lbs and most don't need thant much capacity.

We sell more 49 lbs wing than any other size.

Why?

Most exposure suits are less than 30 lbs buoyant and few divers carry more than 16 lbs of back gas.

Keep in mind that the math is the same for singles vs doubles, but the assumptions are a little different.

The quick and dirty method is suit buoyancy + weight of back gas + 3 lbs = minimum wing capacity for doubles.

Tobin

 

[bj139]

In January, I went to my LDS, to give them some business, thinking to buy a 32lb wing. They had to order the one I wanted but they had a Zeagle 44lb bungied wing on display. They told me I would need more lift than 32 lbs for a single HP117 so I bought the 44lb wing. The wing works OK but I now see I am overwinged for a single tank with drysuit.

If I wear a 7mm wetsuit with double layer body core (~30lbs) plus 7 lbs of backgas I would need 40 lbs of lift and 30 lbs of lead so I could still dive if my drysuit seal became torn. 44lb may not be the optimum lift but will give me a little extra capacity if needed.

Thank You Tobin, for the useful information.

Bill

 

[cool_hardware52]

If I wear a 7mm wetsuit with double layer body core (~30lbs) plus 7 lbs of backgas I would need 40 lbs of lift

No, not really. If your suit is truly 30 lbs positive you could use a 35 or maybe a 30.

Tobin

 

[bj139]

Someone on SB actually took a FJ wetsuit into the pool and needed 31 lbs to sink it. In December, I bought a 7mm FS and a 7mm step in hooded vest so it might be more buoyant than a FJ.

Does the formula you stated above apply to single tanks or only to doubles and why?
Does the 30 or 35 lb wing get me neutral or just positive enough to be able to swim up?

Bill

I just realized the suit would not lose all of it's buoyancy so a loss of say 20 lbs + 7 lbs of backgas; 27 lbs. I was trying to justify my LDS selling me a too big wing. How about if I dove with the drysuit in 33F temp and needed the really thick undergarment so a complete drysuit flood would result in loss of all buoyancy? Of course, there is ditchable weight.

 

[cool_hardware52]

Someone on SB actually took a FJ wetsuit into the pool and needed 31 lbs to sink it. In December, I bought a 7mm FS and a 7mm step in hooded vest so it might be more buoyant than a FJ.

Does the formula you stated above apply to single tanks or only to doubles and why?
Does the 30 or 35 lb wing get me neutral or just positive enough to be able to swim up?

Bill

I just realized the suit would not lose all of it's buoyancy so a loss of say 20 lbs + 7 lbs of backgas; 27 lbs. I was trying to justify my LDS selling me a too big wing. How about if I dove with the drysuit in 33F temp and needed the really thick undergarment so a complete drysuit flood would result in loss of all buoyancy? Of course, there is ditchable weight.

The math is the same for single and doubles, but the assumptions are a little different.

Do you expect your 30 +lbs positive exposure suit to be more or less positive at 15 ft than it was at the surface?

There in lies the answer as to why you don't need a wing equal to the buoyancy of your suit + the weight of gas in a typical single cylinder when diving in a highly buoyant suit.

Tobin

 

[selytch]

Spreadsheet has been updated - some bug fixes in formula calculating doubles.

 

[shamufish]

Ok I apologize if this is a dumb question, but for some reason the calculator seem to think that I'll never need to use weights.
I leave all options by default, enter 6 for the wetsuit at surface (3 at depth, no idea what to but but I thought 50% was good enough). I used that figure because someone in the thread said the average was 3 per mm of neoprene.

I clearly need weight (I used I think ~10lbs when doing my OW cert) so clearly something's not right... what am I doing wrong?

And also, how do you determine the impact of compression at depth on your wetsuit? Just the usual Air Volume = 1/ Pressure?

 

[selytch]

Thank you for the question!
Make sure you put 0's in Backplate (BP), light, and doubles - unless you use any of those (in step 1).
This way I get 4# of lead needed. Suite may be little more buoyant, add 1-2 pounds for that.
For OW class instructors often use extra weight to keep students down...

 

[shamufish]

Thank you for the question!
Make sure you put 0's in Backplate (BP), light, and doubles - unless you use any of those (in step 1).
This way I get 4# of lead needed. Suite may be little more buoyant, add 1-2 pounds for that.
For OW class instructors often use extra weight to keep students down...

Thank you -

Downloading the original spreadsheet, changing the tank to an AL80, adding +4 pounds in 'others' and putting 6 for exp. suit and 1.5 at depth, i get 0# of lead needed, 18.4# of lift.

Maybe there's no need for lead in these conditions?

 

[greene.phillip]

Anyone have a good link for this?