How Much Lift For Doubles?

[jsmith89]

I just got a 35# OMS Wing. Looking on the label it says it can be used with either a single or double 20L cylinders. 35# doesn't seem like enough to me to be used for doubles. Am I wrong? Will this wing work with double?

-Jacobi

 

[DA Aquamaster]

You need to have enough lift to offset the swing weight of the gas in your tanks plus the loss of bouyancy that will occur with wet suit compression at depth. So it depends on both your thermal protection and your tanks.

If you are wearing a 3 to 5mm wetsuit or a shorty that will not leave you excessively negative at depth it may work fine. That makes it however a mostly warm water proposition. In my experience, 45 lbs of lift is needed if diving with doubles in cold water with a 7mm wet suit. If you are adding a stage bottle or deco bottles to your doubles in cold water, 60 pounds of lift is preferable to have.

Diving with doubles and a 35 lb wing will also require that your tanks not leave you over weighted given the minimal weight requirements with the thin wet suit. AL 80's are positively bouyant near the end of the dive and only a few pounds negative when full, so they tend to work very well when diving doubles with a wet suit.

Some steel tanks are also a possibility (steel 72's etc, E7-100's etc), but some steel tanks are negative enough at the beginning of a dive that you would be overweighted in a thin wetsuit or shorty even if you wore no other weight. When you add the effects of wet suit compression at depth, a small capacity wing could leave you negatively bouyant at depth, at least with nearly full tanks.

One other issue to consider is what you are using the wing with. Most single tank wings are pretty narrow and can be restricted from fully inflating by the limited space between the backplate and tanks. So in some cases they work fine with a Transpac or IQ Pack where the wing can fully inflate, but do not offer enough lift with a backplate where they may not be able to fully inflate, particularly with large diameter tanks.

Finally, there is some variation in wing capacity caused by manufacturing variations in both bladder size and the size of the outer covering of the wing that may constrict the bladder itself. It's not unheard of for the actual lift to vary 2 or 3 pounds each way, so a 35 lb wing may be 32 pounds or it could be 38. That 6 pound extreme spread can make a big difference.

 

[ProfessorAronnax]

35# is great for singles but a little light for doubles in my opinion

 

[Hoosier]

You also need to consider the wing size with a lift.

DR rec. wing can be used as a single and double set up. It is 55lb wing. So, go figure.

 

[FishDiver]

You need to have enough lift to offset the swing weight of the gas in your tanks plus the loss of bouyancy that will occur with wet suit compression at depth. So it depends on both your thermal protection and your tanks.

In my experience, 45 lbs of lift is needed if diving with doubles in cold water with a 7mm wet suit.

Diving with doubles and a 35 lb wing will also require that your tanks not leave you over weighted given the minimal weight requirements with the thin wet suit. AL 80's are positively bouyant near the end of the dive and only a few pounds negative when full, so they tend to work very well when diving doubles with a wet suit.

I realize this thread is 13 months old. I thought I would revive it rather than post an identical new thread.

I plan on diving a Zeagle Stiletto with a 35# wing with a 88cf aluminum tank on back and another 88cf tank slung. I will be wearing a 7mm wetsuit. I also carry a SMB with 20-30# lift. I use 20# of lead for the rig. Each tank is 4# positive when empty.

This combo has worked out fine on test dives to 20 meters. I plan to use the rig for brief 45 meter wreck dives. I feel the use of the aluminum tanks will compensate for the thick wetsuit but I would like to hear opinions and comments.

And no, I will not buy a set of manifold doubles!