Wing Lift For Double Hp100

[rjack321]

Ive used a 55lb horseshoe with double lp85s, its not as nice as a 40lb wing but its not dangerous.

 

[Brandon]

I regularly dive dry with HP100 doubles + standard technical gear and started with a 40lb wing (Halcyon Evolve). What I found was that it would barely float my rig at the surface. If diving HP130s, it wouldn't float it alone at the surface, and it would barely float me + my rig at the surface. When I switched to heavier winter undergarments and added my 8lb v-weight, I was negative at the surface with the wing jacked all the way full. All combinations were diveable, but they weren't ideal. Biggest problem is that if I removed my gear in the water (I dive off small boats a lot)... it tended to sink. Do not like that.

I switched to a 60lb Evolve and haven't looked back. I do not notice any serious taco-like problems or difficulties with gas transfer with the 60lb wing. Halcyon recommends the 40 pound wings for aluminum cylinders, and the 60 pound wings for steel cylinders.

 

[CptTightPants21]

I dive worthington hp100s with a Oxycheq 50lb wing. In my opinion 40 is a tad too light, with perfect being anything with 45-55lb of lift.

-20 for doubles
-5 for regs/manifold
-5 for light, aluminum plate
-4 for one stage
I also have -5 for trim weights,

Numbers are round figures, but add an extra tank or two, add some weight somewhere and you are over the capacity of a 40lb wing. 40lb wings are great for double al80s, but if you have steel tanks I want a wing that has a little buffer in terms of excess capacity which is why I opt for a 50-55lb wing.

 

[eelnoraa]

I dive worthington hp100s with a Oxycheq 50lb wing. In my opinion 40 is a tad too light, with perfect being anything with 45-55lb of lift.

-20 for doubles
-5 for regs/manifold
-5 for light, aluminum plate
-4 for one stage
I also have -5 for trim weights,

Numbers are round figures, but add an extra tank or two, add some weight somewhere and you are over the capacity of a 40lb wing. 40lb wings are great for double al80s, but if you have steel tanks I want a wing that has a little buffer in terms of excess capacity which is why I opt for a 50-55lb wing.

I totally see your math. My gear weight are exactly what you listed. I remember checking for if they float by themselves, they were OK with margins. But looking at your number, it should be marginal at best. I will check again on next dive

 

[cool_hardware52]

I know this can be a loaded question and depends on a variable of things but im trying to get a general idea of what I should be looking for as far as lift capacity is concerned. I will not be diving with a canister light but I will be eventually diving with two stage bottles (probably 40cu stages) if that will impact anything. Thanks!

Nothing loaded about your question. It's one I answer about 2x a week.

Back gas volume does impact required lift capacity, but the type of cylinder usually does not.

2 x 100's will hold ~16 lb of air or Nitrox, a bit less with Trimix, but in the range of dives that 2 x 100 make sense for the typical He % won't be very high so we can ignore that.

Tank diameter has almost no impact on wing selection. Manifold spacing can, and smaller diameter tanks allow the use of shorter (closer center to center distance) manifolds, but most modern manifolds are 215 mm C to C. 7 inch tanks with a 215 mm manifold and 8 inch tanks with a 215 mm manifold will have almost exactly the same amount of tank wrap, ~1/2 inch.

A set of 7 inch tanks with a 185 mm manifold vs 8 inch tanks with a 215 mm manifold would result in a considerable difference in wrap, but 185mm manifolds are quickly becoming a thing of the past.

The basic math problem for required lift with doubles is:

The weight of your back gas + the buoyancy of your exposure suit + 2-3 lbs.

Note that tank material, and stage or deco bottles are not part of the calcs.

Buoyancy Compensators are used to compensate for things that change, and that's pretty much only your back gas and suit.

Slung bottles can be passed off or ditched, and as such are not part of your ballast, or something that impacts wing calcs.

The basic assumption for doubles is mandatory deco, and that includes the possibility of having to deco on your back gas. That means you need to be able to hold a shallow stop with near empty back gas tanks.

To do so you need to start the dive negative by the weight of your back gas, + 2-3 lbs.

The additional 2-3 lbs is to allow the diver to add gas to their drysuit at their shallow stop. If the diver is forced to deco on back gas (vs accelerated deco gases) their shallow stop times get looong, and the extra inflation gas helps with thermal management.

If a diver is weighted so they are negative by the weight of their back gas +2-3 lbs they will need to use this much of their wings capacity just to stay at the surface at the start of the dive. They need to have in reserve wing capacity at least equal to the buoyancy that can be lost in the event of a total failure of their drysuit. Keep in mind that dry suits lose buoyancy not because water can get in, but because gas can get out.

What about deco / stage bottles? If our diver starts the dive with an intact dry suit they will have plenty of unused wing capacity to deal with aluminum deco bottles. A full al 80 rigged with a stage kit and regulator is about -4 lbs.

What if this diver suffers a total suit failure early in the dive, and has nearly full back gas and full deco bottles? Pass off the deco bottles, or drop them. The diver does not need the deco gas as they have not incurred much of a deco obligation.

What if the diver suffers a suit failure late in the dive and *really* needs the deco gas to help get out of the water sooner? They have been breathing something (back gas or stages) and are lighter, no need to drop the deco bottles, remember 2 full al 80's are only -8 lbs.

2 x 100's hold 16 lbs of gas
Add 3 lbs ........19 lbs.

Typical shell suit with thicker undies, usually 22-28 ish lbs buoyant.

19+ 28 = 47 lbs. (It's not chance that we sell a *lot* of Torus 49 lbs wings to new doubles divers, )

Test your suit. You want know how buoyant your exposure suit is, it makes weighting questions easy to answer. Avoid steel doubles in the ocean in a wetsuit, bad idea. The basic problem is with negative steel tanks you won't have much if any ditchable ballast. With al 80's you would.

Tobin

 

[Colliam7]

is there any downfall with going with a 50 or 55lb lift wing? I am diving dry FYI and do both fresh and salt water.

It seems the question morphed a bit, from 'what is the ideal' to 'Is there a problem with a 50-55lb wing?' You have some good answers to the first question. I will echo the comments of several posters regarding the second: I like 50 lb wing (Oxycheq) for my double HP100s (with an AL40 and an AL80) I have also used an older Dive Rite Rec wing (horseshoe, with 51 lbs lift), a Halcyon Explorer (wide wing, 55 lbs lift), and even a 60 lb wing with that configuration. All of them work. Notably, the Rec wing is probably my least favorite. To anser your question, you can use a 50-55 lb wing and it won't be a hideous experience at all.

 

[CaptainJackBrittan]

Can a 60 lb wing lift hp100 doubles with an hp100 deco bottle (3 hp100s)?

 

[runsongas]

how do you plan on trimming that config?

i would look at an al72/80 and an al30/40 or two lp45/50 instead.

 

[rhwestfall]

Tech diving is expansive

and expensive too

 

[cool_hardware52]

Can a 60 lb wing lift hp100 doubles with an hp100 deco bottle (3 hp100s)?

To expand a bit on runsongas's point concerning trim.

Your question is one for your instructor, and if your instructor is advocating using negative steels for deco / stages you *might* want to expand your instructor search a bit.

To your questions concerning lift: Wing capacity is a function of the volume of your back gas, and the buoyancy of your exposure suit, not tank material.

You provided the volume of back gas, but zero info on the exposure suit.

Tobin