Using a wing set-up for recreational diving?

[cool_hardware52]

Tobin, isn't that a bit too broad? One of the things the wing needs to do is float your gear on the surface. Somebody using a full HP130 has several pounds more gas than someone in an Al80, and the tank is more negative, as well. So that person is going to need more lift to float his gear, no?

Not really. The buoyancy of the diver's suit dominates the selection criteria.

If you have little to no suit, then you need a lightweight plate and buoyant tank or you will be substantially over weighted.

OTOH if you have a buoyant suit then the tank you choose is very unlikely to drive the minimum wing requirements.

The solution to being over weighted is never a bigger wing.......

Tobin

 

[MXGratefulDiver]

... the buoyancy of the suit won't do you much good if you're diving off a RIB or for some other reason need to remove your rig in the water. At that point, you'd better have enough lift in your wing to keep your rig afloat. And your buoyancy requirements at that point are going to be independent of the suit you're wearing.

Sorry Tobin, your statement is too broad. I've seen rigs that sank when separated from their diver because the wing was too small to float the rig without them wearing it. I get your math, I just don't think it's as universally applicable as you make it out to be. Your rig should be able to float at the surface without you in it ...

... Bob (Grateful Diver)

 

[cool_hardware52]

... the buoyancy of the suit won't do you much good if you're diving off a RIB or for some other reason need to remove your rig in the water. At that point, you'd better have enough lift in your wing to keep your rig afloat. And your buoyancy requirements at that point are going to be independent of the suit you're wearing.

Sorry Tobin, your statement is too broad. I've seen rigs that sank when separated from their diver because the wing was too small to float the rig without them wearing it. I get your math, I just don't think it's as universally applicable as you make it out to be. Your rig should be able to float at the surface without you in it ...

... Bob (Grateful Diver)

Bob, when have I ever advocated using a wing too small to float your rig?

Let me help, never.

The fact remains that for recreational single tank diving the *size* of the cylinder just is not a factor in wing selection, if the diver has anything approaching a balanced rig.

Are you advocating diving grossly over weighted?

Tobin

 

[Nemrod]

I dive from a kayak and as well from my boat and I often don and doff in the water. The wing must float the assembled rig.

N

 

[cool_hardware52]

I dive from a kayak and as well from my boat and I often don and doff in the water. The wing must float the assembled rig.

N

I agree. Anyone who has the slightest familiarity with my many many posts on wing selection would note that I have *always* said that any BC needs to meet two criteria; 1) Be able to float the diver's rig at the surface with a full cylinder 2) Be able to compensate for the maximum possible change in buoyancy of the diver's exposure suit.

I challenge anyone to find a post of mine where I've advocated wings too small to float the diver's rig at the surface with a full cylinder.

Having said the fact remains the exposure suit used is the primary factor in determining required wing lift for a properly weighted diver.

Reasonably fit Divers using little to no exposure suit need to be careful in selecting a back plate and cylinder or they will be over weighted. That often means Stainless plates with buoyant tanks and lightweight plates for negative steel tanks, but it almost never impacts wing selection.

Divers in more buoyant suits have bit more flexibility in plate and or cylinder choice as they have a larger ballast "budget", i.e. they can add more items that might be negative before they are over weighted, but the process starts with the buoyancy of the exposure suit.

Do divers with larger cylinders use higher capacity wings? Often they do, but it's because they also have more buoyant suits that allow them to carry more things that are negative.

In warm water floating the rig is almost always the controlling factor for wing selection simply because the exposure suits aren't very buoyant.

There is no BP&W combo I know of that's a good idea for 2mm Dive skins (or less) and Negative steel tanks. The lightest plates and harnesses are about -2 lbs, a reg is ~-2lbs and a typical steel tank is -2 empty. That's 6 lbs of ballast to offset maybe 1 lbs of exposure suit.

This diver is far better off with a buoyant al 80, i.e. suit buoyancy drives tank selection, not wing capacity.

OTOH the diver in a 7mm suit that's ~20 lbs positive can safely use the negative steel tank, stainless plate etc. but here again the suit buoyancy is what controls the minimum required wing capacity.

It's a mistake IMO to suggest to newer divers that wing choice is a function of tank size, when the puzzle starts with the buoyancy of the suit.

This leads to divers believing it's ok to be over weighted as long as they have enough "lift"

Yikes

Tobin

 

[MXGratefulDiver]

Bob, when have I ever advocated using a wing too small to float your rig?

Let me help, never.

The fact remains that for recreational single tank diving the *size* of the cylinder just is not a factor in wing selection, if the diver has anything approaching a balanced rig.

Are you advocating diving grossly over weighted?

Tobin

Not at all ... I just found something missing in your logic. You said the buoyancy of the diver's suit dominates the selection criteria. If that were the dominant selection criteria, then with many cold-water divers there would be no need for a wing at all. It must, therefore involve more than that. I'm simply pointing out what that "more" could be.

Personally, I think there's too much emphasis on minimizing wing size ... particularly with some of the streamlined designs we have to choose from today, since streamlining is the primary reason for wanting to select the smallest wing you can get away with. I've found no discernible difference in streamlining between a 27 lb wing and a 35 lb wing ... but those eight lbs of lift could very well be the difference between floating a rig or not, irrespective of how much weight you were wearing.

It's not about being over weighted ... you can wear the correct amount of weight regardless of the size of your wing. It's about considering all of the factors that need to be considered when deciding what's the optimal size wing for you. Being able to float your rig without you wearing it is certainly one of the factors that should be considered.

... Bob (Grateful Diver)

 

[cool_hardware52]

Not at all ... I just found something missing in your logic. You said the buoyancy of the diver's suit dominates the selection criteria. If that were the dominant selection criteria, then with many cold-water divers there would be no need for a wing at all. It must, therefore involve more than that. I'm simply pointing out what that "more" could be.

Suit buoyancy does dominate the selection criteria, it's easily the single most important, and apparently misunderstood element in determining how much "lift" is needed.

The diver's exposure suit is the *only* thing that loses buoyancy with respect to depth. Buoyancy Compensators are used by divers to er, ah well, Compensate for this change. It's not even logic, it's simple physics.

Tobin

 

[TSandM]

No, Bob, I've heard Tobin's discussions of dry suits. If it takes 26 pounds to sink me in my undergarments, then in theory, I could lose 26 pounds of lift with a suit flood, which means I need at least 26 pounds of lift, and probably more, because my rig is negative at the beginning of a dive, as well. That 26 pounds of dry suit lift is certainly going to be more than the weight of a plate and even a big steel tank, even with weight plates on the rig. Most of us don't wear all our weight with single tanks on the rig itself, although if you do, that might well have a huge impact on the wing size needed to float the equipment.

With a wet suit, in cold water, I agree that the suit buoyancy is going to be by far the biggest contributor to the requirements for lift. With a dry suit, I think things get a little muddier.

But we are picking nits here. The bottom line is that the rig must float your equipment, and compensate for the real or potential buoyancy loss of your exposure protection. I do think tank size plays a role here, but it probably is not the biggest one.

 

[cool_hardware52]

No, Bob, I've heard Tobin's discussions of dry suits. If it takes 26 pounds to sink me in my undergarments, then in theory, I could lose 26 pounds of lift with a suit flood, which means I need at least 26 pounds of lift, and probably more, because my rig is negative at the beginning of a dive, as well. That 26 pounds of dry suit lift is certainly going to be more than the weight of a plate and even a big steel tank, even with weight plates on the rig. Most of us don't wear all our weight with single tanks on the rig itself, although if you do, that might well have a huge impact on the wing size needed to float the equipment.

With a wet suit, in cold water, I agree that the suit buoyancy is going to be by far the biggest contributor to the requirements for lift. With a dry suit, I think things get a little muddier.

But we are picking nits here. The bottom line is that the rig must float your equipment, and compensate for the real or potential buoyancy loss of your exposure protection. I do think tank size plays a role here, but it probably is not the biggest one.

Dry suit or wetsuit, the number one must be able to compensate for is the maximum possible change in buoyancy. If you want to be able to keep significant gas in your drysuit at your shallow stop your need to start with that buoyancy number as the minimum wing capacity.

Tobin

 

[redacted]

How about a real example:

I'm going to dive a FW spring, 70 F, max of 30 ft deep. I'll use my homemade Al plate that weighs in at 6 lb, my PST E-7 100 (-1 empty, -8.5 full), my Scubapro Mk7/BA/ADJ (-4), and a 2lb light. My 5mm full suit takes 14 lb to sink and I can use a couple more pounds on my waist to keep from getting too light at the end of the dive.

I could put my 18 or 20 lb wing on it and be fine UW. But I usually use my 30 lb wing that probably only gets about 25 lb. If I set the rig in the water, it requires the wing to be full to float that rig. I threw it in once with the wing less than full and had to chase it. The 18 or 20 wing might not be able to hold it at the surface at the beginning of a dive.

The wing really needs to do 2 jobs. For one, your well-being may depend on it. For the other, your gear may.