Wing size vs. exposure suit

[Romko]

I have been diving with Steel 100cf tank (Full: -10 lbs/empty: -2lbs) using
two different exposure suits: dry suit (+22lbs) and wet suit (+20lbs).

Is there any difference in wing size selection when considering both suits
(I have been considering either Torus 26 or LCD 30)???

Thanks in advance. Roman.

 

[Rainer]

Very likely not. Your suits are only #2 different. Worst case, at depth your wetsuit (completely) compresses, or your drysuit (completely) floods. Regardless, you'd need (almost) the same lift.

 

[Romko]

Ok. This is a part I am a little bit confused about. Let’s consider two cases:

• Diving with wet suit.

Initial weighting:
wet suit +20 lbs
rig (BP+Reg) -8 lbs
tank – end of dive -2 lbs
lead (@15ft) -10 lbs

At the beginning of the dive @ depth: rig (-8lbs), full tank (-10 lbs), lead (-10lbs)

Total: -28lbs (assuming total compression of wet suit).

This means I would need at least 28 lbs lift to be neutral @ depth. Assuming I can be off
by 2lbs I could go with LCD 30???

• Diving with dry suit:

Initial weighting:
Dry Suit +22 lbs
rig (BP+Reg) -8 lbs
tank – end of dive -2 lbs
lead (@15ft) -12 lbs

At the beginning of the dive @ depth: rig (-8lbs), full tank (-10 lbs), lead (-12lbs)

Total: -30 lbs. This assumes flooding of the dry suit which I would consider an emergency situation (necessary to ditch some weights).

I could safely assume that dry suit can be compresses up to half of its buoyancy.
Then I would need only 30lbs – 10 lbs (buoyancy of my dry suit) = 20 lbs wing??? I could be off by 2 lbs with my calculations: Torus 26 would be fine in this case?


Do my calculations make sense or I am missing something???

 

[cool_hardware52]

Ok. This is a part I am a little bit confused about. Let’s consider two cases:

• Diving with wet suit.

Initial weighting:
wet suit +20 lbs
rig (BP+Reg) -8 lbs
tank – end of dive -2 lbs
lead (@15ft) -10 lbs

At the beginning of the dive @ depth: rig (-8lbs), full tank (-10 lbs), lead (-10lbs)

Total: -28lbs (assuming total compression of wet suit).

A couple points: Your rig, with a full tank, will be about -18 lbs, 6 for the BP& Harness, 2 for your reg, and 10 for a full bottle. Your wet suit cannot loose more buoyancy than it starts with, 20 lbs. If you start the dive neutral at the surface with no gas in your wing and a full tank the maximum buoyancy you could loose would be 20 lbs due to suit compression. That assumes you can and want to reach -165 fsw on a single tank without actually breathing on the way down.

You are assuming that you need to negative by the weight of your gas at the start of the dive. Remember that you will typically consume about 6-7 lbs of gas from your 100 cuft cylinder. Your wetsuit, which is +20 at the surface, will not be + 20 at 15 ft, the compression of your suit will offset most or all of the weight of the gas consumed. This approach of course only works when using fairly thick wetsuits and reasonably sized single tanks. If you were diving in just a skin you would need to be negative by the weight of your gas, as you have nothing to compress.

[*] Diving with dry suit:[/LIST]Initial weighting:
Dry Suit +22 lbs
rig (BP+Reg) -8 lbs
tank – end of dive -2 lbs
lead (@15ft) -12 lbs

At the beginning of the dive @ depth: rig (-8lbs), full tank (-10 lbs), lead (-12lbs)

Same basic answer here too. You are overweighted. Your dry suit that's +22 at the surface will not be +22 at 15 ft if you allow it to "shrinkwrap" at 15 ft. Your rig is still -18 max, and your suit can only loose 22 lbs of lift from a total failure. If you start the dive neutral at the surface with no gas in your wing and a full cylinder you can loose at most 22 lbs from a total suit failure. Each additional lbs that you are negative at the surface will require an additional lbs of wing capacity.

Keep in mind that the assumptions I'm making apply only to NDL diving in fairly heavy exposure protection. If you were in doubles, I would want you to be negative by the weight of your gas at a minimum.

Tobin

 

[Romko]

Thank a lot for explanation. I was missing couple of assumptions that you made.
Right now I have much better picture.

-Roman