Using a wing set-up for recreational diving?

[cool_hardware52]

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.

If you hang all of your ballast on your rig, you need a bigger wing. One of the key reasons I'm not a fan of doing so.

Even if you started with a buoyant al 80 and added more ballast to your rig to get the same net buoyancy with an empty cylinder you have exactly the same problem. The choice in tank won't impact the lift requirements.

Ballast requirements are driven by the choice in exposure suit. How you choose to carry the ballast can impact required wing capacity.

BTW, How do you get an al plate to be -6 lbs?

Tobin

 

[redacted]

If you hang all of your ballast on your rig, you need a bigger wing. One of the key reasons I'm not a fan of doing so.

Even if you started with a buoyant al 80 and added more ballast to your rig to get the same net buoyancy with an empty cylinder you have exactly the same problem. The choice in tank won't impact the lift requirements.

Ballast requirements are driven by the choice in exposure suit. How you choose to carry the ballast can impact required wing capacity.

BTW, How do you get an al plate to be -6 lbs?

Tobin

I prefer an AL80 or Al63 for that dive but the HP 100 works OK.

I made the plate from some 1/4 aluminum stock I found. It come in around 5 lb. I also added a couple chunks of lead behind each shoulder blade to balance it a little better in SW with that HP100. It may be ugly, but it dives OK.

Snorkel attachment to BP under wing. - ScubaBoard Gallery

 

[cool_hardware52]

The fact remains that the further you move away from the equator the bigger wings get. It's not because the tanks get bigger, it's because the water gets colder and the exposure protection gets thicker and more buoyant……..

Tobin

 

[Michael Guerrero]

I use a backplate and wing for all my diving. I have a 30# wing for single tank, and several wings for doubles. Same configuration, same gear, every dive makes for good responses to unplanned events.

 

[PCoetzee]

Tobin, isn't that a bit too broad?

Agreed. If no correlation exist between wing size and the rest of the load out then why so many different sizes on the market? I use different sizes for recreational and technical. I also have different sizes for my 2x12l doubles and my 2x15l doubles.

 

[nimoh]

Agreed. If no correlation exist between wing size and the rest of the load out then why so many different sizes on the market? I use different sizes for recreational and technical. I also have different sizes for my 2x12l doubles and my 2x15l doubles.

Just to be clear, Tobin is talking only about recreational diving where the diver is properly weighted. In technical diving, larger capacity wings are commonly used due to being overweighted with stage and deco bottles.

Although I agree it is a bit too broad, it isn't far off the mark either.

 

[cool_hardware52]

Just to be clear, Tobin is talking only about recreational diving where the diver is properly weighted. In technical diving, larger capacity wings are commonly used due to being overweighted with stage and deco bottles.

Although I agree it is a bit too broad, it isn't far off the mark either.

Properly selected Stage and deco bottles very seldom impact required wing capacity either…..

Tobin

---------- Post added June 12th, 2015 at 07:25 AM ----------

Agreed. If no correlation exist between wing size and the rest of the load out then why so many different sizes on the market? I use different sizes for recreational and technical. I also have different sizes for my 2x12l doubles and my 2x15l doubles.

Simple, water temps differ across the globe and divers use a widely varying amount of thermal insulation, from *nothing* to 2 piece 7-8-9 mm "Farmer John" wetsuits and Drysuits with High Loft undies.

Again, wings get bigger as one moves from the equator towards to the poles, and divers add more insulation. Tanks OTOH don't get magically larger as you move toward the poles.

Tobin

 

[nimoh]

Properly selected Stage and deco bottles very seldom impact required wing capacity either…..

Tobin

sorry, I misunderstood. I'll change my answer to it is too broad, rather than a bit too broad

 

[cool_hardware52]

sorry, I misunderstood. I'll change my answer to it is too broad, rather than a bit too broad

Deco bottles aren't part of your ballast, and they very seldom impact required wing capacity.

My recommendation is a diver in doubles, independent of any slung bottles, should be negative by the weight of their back gas +2-3 lbs, and their wing should be sized as follows:

Weight of their back gas + buoyancy of their suit + 2~3 lbs.

Let's look at a typical diver in a dry suit that is + 26 lbs with minimum gas in it, and is using 2x hp 100's


Hp 100's hold about 16 lbs of air or nitrox

16 lbs of Back gas + 26 lbs of suit buoyancy +3 lbs = 45 lbs. That makes a DSS Torus 49 a reasonable choice.

If this diver starts the dive negative by the weight of their back gas (16 lbs) + 3 lbs (extra dry suit inflation allowance) they will need to use about 19 lbs of their 49 lbs wing to remain at the surface.

That leaves 49-19 = 30 lbs wing lift to 1) get their chin out of the water at the surface 2) deal with the negative buoyancy of any slung bottles.

Lets say they need 10 lbs to get comfortable at the surface. That leaves 20 lbs for slung bottles.

An al 80 full of air or nitrox, fitted with a stage rig and regulator is about -4 lbs, al 40 about -3 lbs.

They have enough wing to carry *5* al 80's before they run out of wing capacity.

Divers using 5+ stage bottles aren't reading ScubaBoard to find out how to size wings……..

Dazzle me. Show me how this diver can use a smaller wing if he dives without any slung bottles.

The weight of his basic rig won't change if he leaves the slung bottles on the boat.

The buoyancy of his suit won't change if he leaves the slung bottles on the boat.

The requirement to be able to hold a shallow stop with empty back gas tanks won't change if he leaves the slung bottles on the boat.

Tobin