Determining the best size wing

[ppo2_diver]

I'm thinking about moving to a bp and wing setup. What are some of the things I should consider when purchasing a wing? Does my body mass need to be factored in for determining lift capacity? I'm 6'3" at 240 lbs.

Thanks for any help you can give me.

Duane

 

[matt_unique]

I'm thinking about moving to a bp and wing setup. What are some of the things I should consider when purchasing a wing? Does my body mass need to be factored in for determining lift capacity? I'm 6'3" at 240 lbs.

Thanks for any help you can give me.

Duane

This is perhaps a bit off track but I would make sure you need to move to bp and wing. Do your dive profiles require more than 120CF of back gas? I just completed a tech course with divers who just transitioned to the doubles with bp and wings. There is a tremendous increase in weight and of course cost. One diver soon realized the weight of the doubles was extremely difficult for him to manage (physically) in rough seas for example. He had difficulty getting back up the ladder in fact. More importantly I would just make sure you need to drop the wad of cash to make the transition. There were divers in my class who's dive profiles would not come close to requiring more than 120CF of back gas. Perhaps they had other reasons for moving to doubles but I wanted to throw that out there.

I chose to enter the tech realm on single HP steel 120's w/H valve based on my forseable dive profiles. For me these are wrecks at 160' or less. With a HP steel 120 and a 30CF deco bottle you can do a dive to 160' for 30 minutes depending upon your SAC rates and gas planning methodology for example.

--Matt

 

[WreckWriter]

I'm thinking about moving to a bp and wing setup. What are some of the things I should consider when purchasing a wing? Does my body mass need to be factored in for determining lift capacity? I'm 6'3" at 240 lbs.

Thanks for any help you can give me.

Duane

Proper wing sizing depends much more on equipment than body. Assuming you'll be using doubles, most folks here use a 40 lb wing for aluminum 80s and a 55 lb wing for heavier steels. If you're talking about singles you'll probably get more answers in the basic scuba area than the tech area as a BP/wing is no longer considered technical in itself.

WW

 

[NEWreckDiver]

I agree with the others here. Sit down and think about the types of dives you are doing now and want to do in the future. When you start down this road, it does get expensive. I know I just went through this last year.

If you are only planning on doing single tank dives, then stay with a BC. If you are considering doing deep and long dives that require you to have a larger gas supply that will require doubles and deco stops, then you will need to go to a BP and Wing.

The advice I got was to get more than you think you need because you do not want to have to upgrade again later. That will cost even more than just buying the lager wing in the first place.

I personally went with a stainless steel bp and 100lb lift/dual bladder because it will handle anything that I am doing today and plan to do in the near future. The redundancy factor should speak for itself.

This route is costly, but in the long run I know I will not have to upgrade. I hope this has helped you in someway.

p.s., I am originally from Chicago, how is the diving out there in Lake Michigan?

 

[WaterDawg]

Even if all you will ever do is single 80's, I strongly recomend a BP/W. 36lbs should be good for all you single tank needs.

 

[Scubaroo]

Ah, seeing as your original question hasn't directly been answered, here's a stab at it.

If you want to caculate what size wing you need, you need to calculate how negative you will be assuming no inherent buoyancy from a wetsuit or a drysuit, with full tank(s). This is the situation at the beginning of a dive, when your tanks are still full, and you've just descended to depth, and your wetsuit has compressed and lost it's buoyancy.

So add up the following as a rule of thumb -
1. (absolute) negative weight of full tank in current configuration
2. weight of lead on your weightbelt in current configuration

Sample figures here are -4lb for an AL80, and 20lb of lead. So you would need 4 + 20 = 24lb of lift capacity just to get your full tank and weightbelt neutral at depth. Add a couple of pounds for things like regulators, and a 27/30/36lb wing would be appropriate for this config.

Say you're now diving a steel tank and a backplate - how much do you need? Say your tank is -10lb, backplate and STA is -8lb, and you've still got a 20lb weightbelt - that's 38lb of lift you're going to need just to stay neutral at depth. Your 30lb wing is now too small - you're going to want a 40 or 45lb wing.

Go for the backplate - I dive mostly singles, and love it.

cheers

 

[Spectre]

There are two things you need to compensate for with your wing. You need to offset the extra weight you have in gas. For example, a PST 130 has about 10# of gas, so you will be 10# heavy at the beginning of the dive. The other thing is any compressibility in your exposure suit.

What you wear your lead for is to compensate the bouyancy of the suit on the surface [so you can get down], and to replace the gas you use during the dive [so you can control your ascent as your exposure suit expands back].

In general, 27# is a good size for sane size tanks and drysuits or thin wetsuits. 36# would be a little more like it for a thick wetsuit. For doubles, you'd be looking most likely at 45 for thin wetsuits or drysuit with sane size tanks, or 55 for thicker wetsuits, big tanks, stages, etc..

 

[MikeS]

There are two things you need to compensate for with your wing.

I think there is a third thing although it's pretty minor, to compensate for, the negative bouyancy of any ditchable equipment.

Another concideration especially with weight integration is that you might want to have enough lift to float the rig if you take it off in the water.

Mike

 

[netmage]

Ah, seeing as your original question hasn't directly been answered, here's a stab at it.

If you want to caculate what size wing you need, you need to calculate how negative you will be assuming no inherent buoyancy from a wetsuit or a drysuit, with full tank(s). This is the situation at the beginning of a dive, when your tanks are still full, and you've just descended to depth, and your wetsuit has compressed and lost it's buoyancy.

So add up the following as a rule of thumb -
1. (absolute) negative weight of full tank in current configuration
2. weight of lead on your weightbelt in current configuration

Shouldn't #2 be:
Weight of lead differential between diving in a skin to your current configuration?

Part of that lead load is compensating for your own "natural" bouyancy - just to get your neutral at the surface.

 

[Spectre]

I think there is a third thing although it's pretty minor, to compensate for, the negative bouyancy of any ditchable equipment.

If you have ditchable weight that is making you negative... why do you have it? What does ditching it solve?

Ditchable weight, IMHO, should be enough to get you to a point where you can swim your rig in the event of a BC failure. That means, in my eyes, weight to compensate for the gas in your tanks, at the most. If you can't swim against the difference in bouyancy from surface to depth of your exposure suit, you should look at getting something less compressible.

E.g. if you're diving a single 120, I think the weight of the gas is 9 lbs. So if I felt I couldn't swim that, I would carry 2 4# ditchable weights. I can ditch both at the beginning of the dive if needed, or ditch one if my tanks are half full.

The fact of the matter is the weight is there to compensate for the weight of the gas in your tanks that you are going to use. If you have negative weight that you have to compensate for with your BC, that isn't there to replace something like the gas you are using... what's it there for? E.g. if you are lifting the gas in your tanks, and the weight from your exposure sure compression, _and_ some more from your ditchable weight... what is the ditchable weight there for? If you need to compensate for it, then you don't need it in the first place.