Wing sizing?

[Just Don]

My apologies for what may be a redundant post. I'm sure somebody else has asked this, but I couldn't find it in perusing the board here.

I am a new diver looking to get my own gear. Based on what I've read here (and a few other places... but mostly here), I am leaning toward a BP/W setup. I find myself somewhat confused, though, on how to determine what size wing I need in my BP/W setup. Can somebody help me understand how to figure that out?

To summarize what I want to accomplish (as I'm sure that's where the determining factors come from):

• I want a system that works for me as a beginning diver, but that I can also "grow into" as I get experience and learn new things.
• I want to be able to dive in both warm Caribbean waters and in cooler lake waters (but probably only down to as low as mid-to-high 50s; no arctic diving ). That means I need something that will work whether I'm wearing just swim trunks and a rash guard, or a thick wetsuit.
• I want to put together a single, high-quality setup that can be adaptable for all of those situations
• I'm a big guy (5'11", 260 pounds or so), so need a setup that will accommodate a big fella. (Having said that, I'm working to be a smaller guy in the future, so would like it to still work...) When I dove in a warm pool without a wetsuit, I needed eight pounds of weights to get myself to sink.
• The only other gear I have right now is a dive computer, so variations based on stainless steel or aluminum - or anything else for that matter - are still TBD. (My guess is that the sizing varies by the weight of the BP, so a S/S one would require a little more lift than Al.)
• I only plan on single tank dives at this point.

Any assistance y'all can provide would be greatly appreciated.

Thanks!

 

[Hartattack]

Hi Don, and welcome to diving in BP/W!

That's really exciting and I am happy you are headed in this direction. With that said, I think we need a bit more information.

1.) Are you looking to go into tech diving as you advance?

2.) What exposure protection do you have now?

3.) What is your local diving like or what do you dive mostly, is it cool lakes or warm water?

 

[tbone1004]

BCD's are buoyancy compensation devices, ergo they have to compensate for shifts in buoyancy. There are 2 primary considerations that you have to use when sizing a wing for things that shift in buoyancy. Mass of gas in the tank *need more lift at start of dive than at end of dive*, and compression of wetsuit *need more lift at depth than at surface*. Air weighs ~.08lbs/cf and the biggest tank you'll be diving at your height is a HP130, so 130*.08=10.4lbs, call it 10. Suit compression is ~2lbs/mm and at mid 50's you'll be diving a 7mm, so call it 20lbs which gives you room for a hooded vest which I would want with a 7mm steamer.
The second thing it has to do is be able to float your entire rig at the surface if you have to remove it for some reason, typically handing it to surface support or hauling it back into a RHIB or something. That will depend on how you distribute your lead. You probably need about 6lbs to sink yourself, plus the 20lbs of suit, so if all of your ballast is attached to the backplate then you need about 30lbs to deal with that.
Third thing which is not a "need" but is nice to have, is the ability to comfortably hold your whole head above water. If you are diving a balanced rig and are not overweighted, then you should be ~10lbs negative at the start of the dive at the surface based on mass of gas in the tank. Add in ~20lbs of head/neck/first stage/valve sticking out of the water and to comfortably hang out at the surface you probably need about 30lbs of lift.

1- not relevant to wing sizing
2-need to define wetsuit as wetsuit thickness is probably the biggest factor in wing sizing
3-not relevant to wing sizing
4-not relevant to wing sizing
5-not really relevant to wing sizing
6-not relevant to wing sizing, though determines the type of wing you get.

Based on all of that, a standard 30lb wing is probably fine. You would only need to go to a 40lb if you were diving a 7mm farmer john which I don't think is safe for any real depth due to the suit compression, and I don't like going any smaller than 30lbs because you don't really save much of anything in terms of wing size by dropping to a 20lb wing unless you are a short diver and are using things like AL63's

 

[formernuke]

OP do you have any intention on getting a drysuit for your lake diving?

 

[tbone1004]

OP do you have any intention on getting a drysuit for your lake diving?

not really relevant for wing sizing, certainly not compared to a 7mm unless you are carrying all of the extra drysuit ballast integrated to the plate which I would strongly discourage. I use the same amount of ballast for 7mm with a hooded vest as I do in a drysuit though which only affects the surface flotation aspect. Drysuits actually require less lift during the dive than a wetsuit since the suit compression is compensated for by the suit itself.
i.e. a dive that would require a 30lb wing in a 7mm suit would only require a 20lb wing in a drysuit since the drysuit is taking care of itself.

 

[Just Don]

Thanks for the feedback so far. Here are my answers to the questions thus far:

Hi Don, and welcome to diving in BP/W!

That's really exciting and I am happy you are headed in this direction. With that said, I think we need a bit more information.

1.) Are you looking to go into tech diving as you advance?

2.) What exposure protection do you have now?

3.) What is your local diving like or what do you dive mostly, is it cool lakes or warm water?

1. I don't *think* I'm planning on going into tech diving as I advance. Though I'm open to the idea, I really see myself as a recreational diver. If I decided to go into tech diving, I would expect to have to do some upgrades to equipment in any case.
2. Exposure protection? I don't even have any hair on the top of my head to protect me from the elements! On a slightly more serious note, I don't currently own any wetsuits. For my training I used a 5mm long sleeve shorty over a 7 mm farmer john (I think... I might have the 5 and 7 reversed...). I would expect in the future, though, to use a 7mm wetsuit for cold water diving, and a 2-3 mm wetsuit for warm water diving.
3. Local diving is pretty cool lake (down as low as 50s) during the winter and spring, but pretty warm lake (up into the 80s) during the summer and fall. (Texas, y'all...) I hope to go a couple of times per year to a more reliably warm place such as the Caribbean. Overall, though, I would expect to have a relatively even distribution between cool and warm (but a little more fresh than salt water).

OP do you have any intention on getting a drysuit for your lake diving?

At least at this point in time I don't see myself getting a drysuit. I could change my mind in the future, but it's not currently on the roadmap.

 

[formernuke]

I would go with a 30 as mentioned above unless you're using a farmer john/Jane 7mm wetsuit then a 40 wouldn't hurt.

 

[halocline]

There's a super easy answer to your question. Get a 30lb wing designed for single tank use and you'll be happy. It's VERY rare that any single tank diver needs more lift than 30 lbs, and most need less.

Texas lakes rarely get very cold, and there's not a lot to see anyways. (Lake Travis divers will now flame me)

 

[runsongas]

just get a 30 to 40lb wing with a steel plate as your first setup. it will handle single tank diving in a variety of conditions.

 

[fisheater]

There is no "one wing to rule the others." You should plan on getting a smaller wing (say 18-20# for tropical diving with a 3 mm suit with a single tank) and a large wing (say 30-40# for cold water diving with 7 mm farmer john or drysuit and a single tank). When / if you go to double tanks, you'll need a physically larger wing to accommodate two wings. Single wings won't work well with double tanks and visa vera.

That said, the above advice to get a 30# single wing and do both is valid. It's just not ideal.

Fortunately, switching wings is easy.