Why so much buoyancy?

[WetFatCat]

Apparently 30 lb is quite enough for almost any recreational single tank dive. Why popular Zeagle travel BCDs have 35? Why so much extra?

 

[The Kraken]

Well, suppose you require all of that 30 pounds to be neutral at the end of your dive with all of your gear, light, knife, reel, etc.

Because you are now neutral with an Al 80, you would have been humping about 36 pounds of gear at the beginning of your dive because of the weight swing between a full and an empty Al 80.

So, if your gear weighed 36 pounds and your B/C lift was 35 pounds, guess what would happen if you took your rig off at the surface.

B/C's are designed to support a full rig at the surface.

the K

 

[Rainer]

Difference in wing size is also pretty minimal for those 5-6#. In any case, a 20# would probably be fine for most in warm water. For those in cold water, adding a can light and a deco/pony bottle can put you uncomfortably close to 30# lift.

 

[MSilvia]

Consider also that while 30# may be enough for a properly weighted diver, there are a lot of divers out there who typically dive overweighted. They need more lift to compensate for the extra weight.

 

[Rainer]

And instructors who like to take along extra weight.

 

[prthd9]

30# may just be enough for you. It all comes back to weight like Kraken said. I am able to dive a 30# wing in a 7mm, because I need less weight than someone twice my size with twice as much neo.

 

[WetFatCat]

I got it, thanks.
Just thought that 30 wouldn't be enough if i add additional neoprene (vest, or two peace suit) and a light with pony bottle.

I'm in process of wing choice and, as almost everybody. trying to get one wing for both cold and warm water.
Is Torus 35# too bulky for a warm water? Will it trap the air?

 

[Rainer]

I dive a 35# Torus here in local MA waters. I find it quite nice for the diving I do here. I just got back this weekend from a week in Bonaire. I used the same DSS wing on over 20 dives, and it was just fine. Maybe not ideal, but I had no significant problems with trapped air, trim, or streamlining. My gf uses the 26# Torus, which is probably a bit better for these warm water conditions. I had been considering buying a smaller wing for warm water travel, but after this past week, I won't bother. My current singles wing suffices.

 

[aboalreem]

beside what everyone mentioned is ture,,,,diving in neoprene Drysuit, Cold, Salt water, all at the same time, you might need more,,,,it all depends..

 

[cool_hardware52]

Apparently 30 lb is quite enough for almost any recreational single tank dive. Why popular Zeagle travel BCDs have 35? Why so much extra?

A backplate and wing is a modular BC. You can select the combination of plate and wing that are appropriate for YOUR application.

If you understand how gear selection, and exposure suit buoyancy impact the required lift it's possible to choose a wing that is the smallest that adequately meets your needs.

That's not always the case with Jacket BC's. Here the designer has to assume some "worst case" senarios. Will the user be in a thick neo wetsuit? Say a full 7 mm + a 7mm hooded vest? What will the user have for tanks? What will the user do for ballast, i.e. will the user elect to hang all their ballast on the BC?

With these unknowns, and the general lack of understanding about how to determine minimum required lift, the understandable reaction is to build in "lift 'o' plenty. It's common to see BC's with 40-50+ lbs of lift.

The fact that a given BC offers XX lbs of lift is not a reliable indication that YOU need the same or greater.


Tobin