Bp/w Recommendations

[dmaziuk]

I can stay down there with empty tank breathing normally

... with my gills. Doesn't everyone?

 

[yoni]

I've been away for a while, but I'm back.
I am hoping that sometime this week I can get away and do at least 1 dive with someone else's BPW, just to test it out.
I hear and appreciate everyone's input. Speaking from the position of "absolute zero experience" with a BPW, I can't really debate any of these points. The only thing that I can say is that I dive almost exclusively in the Red Sea and the Mediterranean Sea. Both these places are known to be saltier than the oceans (Red Sea about 20% more and the Mediterranean I'm not sure). I know that with the BC that I have now, Bare Blackwing (no longer made), without a wetsuit and with a steel 15 liter tank I STILL need ...get ready for this...something like 10 - 12 lbs to go down (by the way, I dive with very little air in my BC, if any). You don't even want to know what I take with a 7mm and a 12L aluminum tank. I know that this will sound crazy to most of you (and to me as well), and the first thing that will cross your mind is that I'm not breathing correctly. I assure you that I've had many instructors who said the same thing, took me for a dive or 2 to prove their point, and came back saying that with the gear I have they suppose that that's the weight I need. My BC is back inflated w/bungee cords. I suspect the creases caused by the cords make it more difficult to dump the last of the air, which is one reason why I need more weight.
This is the main reason why I am moving to a BPW.

 

[cool_hardware52]

My BC is back inflated w/bungee cords. I suspect the creases caused by the cords make it more difficult to dump the last of the air, which is one reason why I need more weight.
This is the main reason why I am moving to a BPW.

Bungeed "wings" or back inflates can result in convolutions that trap gas.

Tobin

 

[tbone1004]

one needs to also realize that the lift capacity of a BCD is determined by how much water it displaces. I.e. for a standard 30lb/14kg bcd, it is displacing 14l of FRESH water. That same bcd can displace 31.6lbs/14.34kg of standard sea water, and obviously however much more depending on which part of the ocean you are in.

Now, you displace a fixed volume regardless of what medium you are in. The lead required to sink you in the northern part of the Red Sea is obviously significantly more than that in a fresh water quarry, however that does not get factored into your lift requirements unless it is attached to the rig. If it is on a weight belt, it doesn't change your wing requirements. With no additional lead strapped to the rig, the heaviest DSS rig that you would need to compensate for is just under 20lbs *big backplate, with weight plates, and harnesS*, so call it 20 for easy math. In the US, excluding some weird Heiser and MP Faber tanks, the heaviest tank out there is about 15lbs negative *very rare to see these btw*, add in 5lbs for the regulator and misc stuff, and you have 40lbs required to keep that rig afloat at the surface. This is all fixed volume, so as long as it can float it in fresh water, it will have that much easier of a time in the salty stuff.

The Bare Blackwing would not surprise me if it was approaching 4lbs positive on it's own due to the padding in there, so you'll be able to cut down on the lead over and above the straight -6lb advantage of a plate, likely to 0. As long as you keep the extra lead you need on a weight belt, the lift requirements of the wing are still only that of the negative buoyancy of the rig when full, added to the positive buoyancy of the wetsuit. The absolute total of this is what it has to compensate for. A 15l tank to 300bar is about 13lbs, plus 6lbs for the plate, and 2lbs for the regulator, and for that combo you can easily get away with a 30lb wing. With a 3mm wetsuit, it should be no problem either, and on a 7mm wetsuit, with that tank, you may well need to go up to a 40lb, but without you posting all of the variables, we can't nail that one down.

 

[StefinSB]

A stainless plate in thin or no exposure suits and or with steel tanks will over weight the diver. Being overweighted is bad, being over weighted with no means to drop the ballast is worse, and unsafe. In addition being over weighted makes buoyancy control more difficult.

To reduce / avoid being overweighted with thin suits and or negative steel cylinders you need a light weight (much less negative Kydex back plate. (others offer aluminum plates for the same reason)

With thick suits and / or buoyant tanks the ballast that a SS plate provides up over your buoyant lungs and along side a buoyant cylinder is huge benefit. Using a Kydex plate when a SS plate is appropriate leaves most adding ballast via a weight belt, and that usually end up with a diver who is heads up, hips down, not in horizontal trim. Doing so effectively defeats one of the primary benefits of a BP&W, better trim, or more correctly more easily achieved improved trim.

Wings. All BC's are used to replace the buoyancy your exposure suit loses as it compresses. More suit requires more wing. Wings aren't sized based on the frequency with which you dive warm vs cold. One cold water dive a year means you need a wing that can compensate for the maximum possible change in buoyancy of your most buoyant suit.

To meet your range of applications with a single set of gear you need a lightweight (Kydex) plate with a fairly large wing. Probably something in the 26-30 lbs range.

This wing will be larger than you need for warm water, and that leads to more effort venting, less stability and more drag.

The kydex plate means you will need a weight belt (or other ballast) for most of your diving.

How to "narrow" the range?

Use at least a 3mm suit. If that's too warm leave it 1/2 unzipped and "pump" water through the suit if needed.

Stick with buoyant tanks in warm water. That's usually easily achieved as most rentals tend to be al 80's

Doing these two things means a SS Plate will work for warm and cold water.

Doing a careful check of the buoyancy of your cold water suit allows the selection of a cold water wing that is no larger than necessary. While this wing will still be larger than a pure warm water wing could be, it will most likely be only a bit bigger than ideal.

People are attracted to BP&W's because they want a better performing BC. Try not to end up with a sports car fitted with giant truck tires.....

Tobin

That being said. Tobin's wings are very narrow to begin with. We have a few in the family and the torus 26 is to me almost indistinguishable to the lcd 20 in the water. That 26 is a peach of a wing.

 

[tbone1004]

agreed. As long as I am using 6.9" or bigger tanks, LP72's, AL80's, etc etc, I use my LCD30 for everything. I don't dive singles often enough to warrant multiple wings and if I need more lift capacity, I bring my independent double cam bands and dive independent doubles with a 50lb doubles wing. If I was regularly having to dive short tanks, HP80's, AL63's then I might have to re-evaluate, but I'd shoot myself before I dove those things on a regular basis since I'm rather tall

 

[yoni]

Thanks. I am definitely starting to understand all the considerations involved. It will take me a bit of time to do the experiments though. Any time that I will have for diving in the next few week will be very limited, and I'll be mostly in my course. Like I said, I hope to be able to borrow some gear to test out this week.

 

[dmaziuk]

I know that with the BC that I have now, Bare Blackwing (no longer made), without a wetsuit and with a steel 15 liter tank I STILL need ...get ready for this...something like 10 - 12 lbs to go down (by the way, I dive with very little air in my BC, if any).

:shrug: Roatan, two weeks ago, Alu BP and Holis 25 wing, 2mm shorty, Al80: 10lbs. And going down on the first one was hard as everything was bone-dry after the winter. 10lbs surprised me as I previously carried same 10lbs with a rental BCD, same shorty and Al80 in the same sea (Bonaire).

I.e. if you're already close to your proper weighting BP&W may not make that much difference, and if you need 12lbs than you need 12lbs. I like not being 'wrapped' and 'hugged' in the BCD.

 

[yoni]

:
I.e. if you're already close to your proper weighting BP&W may not make that much difference, and if you need 12lbs than you need 12lbs. I like not being 'wrapped' and 'hugged' in the BCD.

I came to to same conclusion right after finishing my open water course many years ago - that I didn't like the BCD jackets hugging the life out of me, which is why I bought a back-inflated BCD. I suspect that my BCD is particularly problematic as far as being too positive and not dumping out all the gas.

 

[stuartv]

Deep Sea Supply has the only STA-Less wing design that I like. Most use rubber tubes to act like a wheel chock between the plate and the tank, but they tend to skew. Tobin integrated a STA into the wing design

Wouldn't it be more correct to say the DSS wing has tank stabilizers integrated into the single tank wing design? If you want to use a BP with no tank strap slots, you still need an actual STA, whether you are using a DSS wing or some other brand.

Even with a steel HP120, I have had no stability issues with my DSS LCD30 wing. But, neither have I had any stability issues with the same tank, BP, and my Hog 23# wing (which has their own design of tank stabilizer built into the wing).

His is the only one that allows the wing to come off without adjusting the cam bands,

Any wing can do this if you use ScubaPro-style quick release tank straps.

Now, the advantages of an STA are as follows. If you are on a pitching boat deck, and you are doing multiple dives with different tanks, having an STA on each tank, and moving the backplate and wing from one to the other

But, a piece of cave line (or other thin line) threaded through the BP and tied to the right length will let you hang your rig on a tank and hold it at the right height while you secure tank straps (at least, if you are using SP-style straps). That seems just about as easy, on a pitching boat, as lining up a wing and a BP and mounting them onto a tank that already has an STA attached. And a piece of cave line is a lot less money than multiple STAs and sets of tank straps, one set for each tank you're going to have on the boat.