Wing size for 12L steel

[Wallowa]

Single-layer is a normal one-piece wetsuit. (I'd term your farmer John a 2-layer.) Since we should weight for neutral near the safety stop (or slightly above), the compression that matters to the wing would be about 7 lbs (based on the difference from 15 lbs, not 21 lb). Regardless, that's less than the 4 kg I originally ballparked above.

I agree that at the safety stop neutral buoyancy is the goal.. the amount of weight/buoyancy to achieve that of course depends on depth of stop and gear weight/buoyancy...but, if positive at safety stop air can be dumped to become neutral...disagree with 7lb estimate however; the weight of all the gear determines the needed buoyancy not just what the wet/dry suit generates at any depth...my SS plate adds -6.5lbs, adapter plate -1.5lbs, regs -2lbs and accessories around -2 lbs; notwithstanding the loss air weight or concurrent gain of buoyancy with some bottles....anyway, still of the mind that having too much buoyancy capacity in a wing/BCD is preferable to not having enough when needed....why guess or trim too close to maximum buoyancy you 'might' need at depth only to achieve the safety stop neutral state with wing/BCD empty or near empty? No big deal really, ESAs are not mythical feats of superhumans and safety stop depths can be adjusted to fit sea states and buoyancy if need be....still unsure why a suggestion to not be capable of positive buoyancy for the wing/bottle/regs/plate/trim weights/'extras' at the surface? One un-attentive moment after getting out of harness at the surface and gone is the gear to the bottom.

Lots of variables and always a matter of personal choice. Appreciate the dialogue and information.

 

[MarkA]

That 6 kg was for actual lead, over and above the tank and plate. It allowed for 1.5-2 kg negative for the tank and 3 kg for the SS plate.

Thanks for your explanation. I should have used numbers with the comment.

-4.2kg. Gas weight
-2.5kg. SS plate
-2.5kg. Bare 300bar cylinder bouyancy.
-1.5kg. Cylinder valve and regulator
This adds up to -10.7kg. This is 2kg less than the 12.7kg bouyancy of the wing.

Referring to @BoltSnap in post #6. The 300bar cylinder is probably 3kg more negative than a 232bar cylinder.

 

[inquis]

Note that the 300Bar 12L specs aren't the same as the 232Bar 12L steel tank.

True, that would take off 2.5 kg from the 6 kg maximum lead calculation.

 

[inquis]

This adds up to -10.7kg. This is 2kg less than the 12.7kg bouyancy of the wing.

Do you use additional lead? If not, then I don't see any issue. If so, is it integrated onto the rig or is it on your person?

 

[inquis]

be....still unsure why a suggestion to not be capable of positive buoyancy for the wing/bottle/regs/plate/trim weights/'extras' at the surface? One un-attentive moment after getting out of harness at the surface and gone is the gear to the bottom.

I stated that one should be positive, which agrees with your position.

the wing does need to float your rig if you remove it at the surface

"Rig" is everything not on your body. BP/W, cylinder, any integrated lead, light, camera (though that should be neutral), etc.

 

[johndiver999]

The initial responses were spot on, then it gets over complicated.

If the guy has some ditchable lead (on his body) then the wing should work. If he tries it and feels he needs more lift, then he can buy a new one, but why not see how the existing one feels?

I personally am in the camp of: having a little excess lift (especially in an emergency) is desirable, but that isn't necessarily required.

 

[Wallowa]

I stated that one should be positive, which agrees with your position.

"Rig" is everything not on your body. BP/W, cylinder, any integrated lead, light, camera (though that should be neutral), etc.

Guess I misunderstood this: "That said, the wing does need to float your rig if you remove it at the surface." hey, I am confused, normal state...but wing/bcd should be able to float 'everything not on your body,' IE 'rig'. Seeing your rig disappear into the deep once off at the surface would be a bummer. Are you saying that even with a deflated wing at the surface your rig will be positive? My empty 80cf Al bottle is +4lbs [less with 500psi] but reg/valve/BP/trim weights/wing-harness weight exceed that.

Again, why not have a wing/BCD capable of 'extra' buoyancy? What am I missing? Tis better to have too much buoyancy in reserve rather than not enough? Not challenge your approach but trying to see the reasoning. Thanks.

 

[inquis]

Are you saying that even with a deflated wing at the surface your rig will be positive?

No.

 

[Wallowa]

The initial responses were spot on, then it gets over complicated.

If the guy has some ditchable lead (on his body) then the wing should work. If he tries it and feels he needs more lift, then he can buy a new one, but why not see how the existing one feels?

I personally am in the camp of: having a little excess lift (especially in an emergency) is desirable, but that isn't necessarily required.

John, don't disagree with having more buoyancy that needed to get you off the bottom depending on the depth of the dive and of course fresh vs salt water.....not certain what constitutes 'excess' as that denotes an optimal amount of buoyancy vs weight through out the dive profile...yes, not really complicated but finding a starting point for your weight vs lift beats finding out on a dive that you were way off in the estimations and are constantly fighting to stay submerge in shallow water or dragging across the bottom in deep water....

Will again voice my preference for always having some ditchable weights. Even at surface when in trouble weights are dropped. We always need to resurface....and stay there

 

[Wallowa]

No.

Help me here....what exactly do you recommend? That your wing and all the gear once off the diver does not have to be capable of positive buoyancy to stay floating at the surface?