First BP/W - which size and model?

[Perozdero]

Hi everyone,

I'm a new diver and looking into getting my own gear with BCD being one of the last things I still cannot decide on... Until now I have only rented jacket style BCDs but reading up I think I want go move to BP/W. First step is to understand the right size of wing.

My worst case scenario would be diving in Netherlands in Salt water at 40m with my Semi-dry suit and 15L steel tank.

Using the buoyancy calculator it gives me that I need 19L wingsize or 15L with droppable weights however in the lift tab it says 15L lift is marginal at depth. I talked with ppl at the dive club and they told me rule of thumb is if you want to dive with 15L tank you should have 17L wing. So what size I should aim for? And what are the drawbacks if I use the same wing also when traveling abroad for warm water diving ?

Now looking at the models available I like the idea behind the Tecline peanut that comes in size 16L and 21L and interestingly I can get the 21L for cheaper than the 16L... or should I just go for a donut shaped wing instead of peanut which come in 17L from tecline or other brand?

Peanut 16 (16kg/35lbs) - TRAVEL SET Light (standard alu BP) - weight 3,05 kg | Tecline Catalog

Peanut 21 (21kg/46lbs) - TRAVEL SET ultra light - weight 2,94 kg | Tecline Catalog

PEANUT 21 TRAVEL SET ULTRA LIGHT DESCRIPTION: - Peanut Travel Set with total weight of 2.94 kg - H-shaped aluminum backplate does not require an additional single-tank adapter - Tecline Peanut 21 Asymmetric Wing (21L capacity) helps to maintain a comfortable, safe position both, underwater and...

katalog.tecline.com.pl

Ultra Light Travel Set: Donut 17, DIR harness, alu BP, trim & weight pockets, tank belts | Tecline Catalog

DONUT 17 ULTRA LIGHT TRAVEL SET This set consists of: - Tecline Donut 137Mono Black with built-in mono adapter - DIR Harness with standard harness - Standard 3mm Aluminium Backplate - 2 standard weight pockets - 2 small trim pockets - 2 tank bands - Transport bag Weight of the whole set: 3,2 kg

katalog.tecline.com.pl

"Donut 10/13/15/17" Ultra Light Travel Set

TECLINE "Donut 10/13/15/17" Ultra Light Travel is an ultra-light, compact and fully ready-to-use set of equipment, designed not only for active divers, but also for all who appreciate reliability, comfort and, of course, ease of use. The total weight of this kit is only 3.2 kg. Technical...

www.diveshop4u.eu

 

[inquis]

Diving a large steel tank in a wetsuit (which is what a semi-dry is) isn't the best idea since a wing failure puts you in a world of hurt. Explore the other tabs in the calculator and you'll confirm that numerically. The best solution (ignoring cost) would be a drysuit, but sticking with the wetsuit, you should have ditchable weight.

Now, given that you have ditchable weight, I don't see the need for the larger wing and associated disadvantages: travel bulk and tendency to taco (trapping air).

Do you have a realistic estimate for your suit buoyancy? That figures largely into the amount of wetsuit compression the wing has to compensate. (The calculator value was way high for my suit.) You can eliminate much of the uncertainty by simply measuring the suit buoyancy in a pool or large trash can. In a mesh bag or pillowcase, put the suit and just enough lead to barely sink it. If you don't have the right amount of lead, use anything heavy enough to sink it and then weigh the bundle (in the water) with a luggage or fish scale both with and without the suit. The difference is the suit buoyancy.

 

[inquis]

Do you already have the 15 L tank? That's starting to get "large", and a 12 or 13 L might reduce the wing requirement (better for warm water travel). For deeper dives, I expect you'd run up against NDL limits first, and thermal limits on shallower dives. Anyway, just food for thought.

 

[Perozdero]

I bought a 15L tank recently that I plan to use for diving in Netherlands. I dived with one both here and Spain (late autumn) with 7mm wetsuit and for deep dives (30-35m) I was having about 45m dive time which I felt helped me keep up with my experienced buddy with 12L. I used 40meters as worst case scenario for the calculator.

Do you think 16-17L is already too big?

Regarding the wing failure at depth, it was also my concern but I plan to have most of my weight on a belt so I hope that should be ok (buoyancy is ~ -5kg after ditching)

I really like your idea for meauriing the suit buoyancy. I was thinking something along the same lines o myself with the gear and measure my buoyancy in a nearby pool or lake) but I like your idea better. I guess for the suit alone a bathtub with water would also work.

 

[inquis]

Do you think 16-17L is already too big?

Yes, but the suit buoyancy is the biggest uncertainty.

The purpose of the wing is to compensate for wetsuit compression and gas weight you haven't yet breathed, which I would estimate maxes out at about 10 kg total in your case. (This assumes you lose all suit buoyancy, which you won't; and a suit surface buoyancy of about 7 kg, but you'd weight yourself as if it were under 5 kg so as to be neutral at 5 m safety stop.)

You might ask your buddies about their reasoning for the 17L wing recommendation. Measure your suit buoyancy so your calculations are realistic. If you indeed only need 10 kg of lift (suit buoyancy loss + gas weight), then a 14 or 15 L wing is plenty in my view.

As an aside, the 2nd consideration for wing size is to float the rig without you in it (e.g., before getting into a low, inflatable boat). Since you're using a weight belt for ditchable weight, the rig will be correspondingly lighter and float perfectly well with a smaller wing. (Note, this may not be the case for your buddies.)

 

[dmaziuk]

You might ask your buddies about their reasoning for the 17L wing recommendation.

30-32 pounds is a common wing size for cold water single tank diving. Depending on how you do your rounding, it'll come to about 16 litres.

 

[inquis]

30-32 pounds is a common wing size for cold water single tank diving.

Quite so, which equates to a 13.5-14.5 L wing.

 

[KenE]

Regarding the wing failure at depth, it was also my concern but I plan to have most of my weight on a belt so I hope that should be ok (buoyancy is ~ -5kg after ditching)

This may be a problem if you have wing failure. If you ditch all your weight on your belt you will ascend dangerously fast as your wetsuit will gain buoyancy as you ascend. I also use a 7mm semi-dry and spread my weight out so I can ditch only what I need to if I get into that situation. I dive mostly from shore and can add weight from the bottom if needed. In open water I carry a lift bag and DSMB for added floatation to reduce the need to ditch weight. You will need that weight to hold your safety and deco stops when required.

 

[Angelo Farina]

16-17 liters with ditchable weights is ok for your case.
Of course with proper setup of your weights.
My one is 20 liters, I also use a 15 liters steel, down to 50m with wetsuit (5mm here in the Mediterranean).
I never needed to fill it much more than half..
The nice thing of the BP+wing is modularity and simplicity.
You can choose the wing you like (albeit I suggest donut), the backplate you like (steel, alu, plastic, fiber, carbon, etc.) and the type of webbing that suits you better (I love those which can be opened on shoulders).
You can have a single webbing acting as your belly belt, or, as in my case, have a large velcro strap instead.
You can add ditchable weights where you like them.
It is all modular and you can usually mix parts of different brands.

 

[Vitesse2l]

In the case of wing failure, as pointed out the smb can be used as extra buoyancy but a ditched weight belt can be attached to a reel and used as an anchor while ascending.

I used a 30lb wing for the same sort of diving the OP is discussing but with a steel backplate.