Lift capacity of BCD

[seatrek]

G'day
Trying to find the right bcd for my needs,
I faced the following question .
How the manufacturer measures the lift capacity of a bcd?

For example if my bcd has 20kg buoyancy that means
my bcd could lift 20kg when I have neutral buoyancy on the surface or
is something else ? (for instance depth factor)

Many recreational BCDs have 16-17kg lift capacity.
If the stucture of the recreational BCD backplate is reliable,
that means could I mount 2x15litres on the BCD? (usually they weight in the water 12kg together) and avoid the purchase of a technical bcd. (Just in terms of lift capacity)

Many thanks
SeaTrek (George - Alimos - Greece )

 

[Halthron]

You'll need a BC that can float everything you have at its heaviest, including the tanks when full and all the weights you're carrying as well as any accessories. You don't care what something weighs at the surface, only what it's weight in the water is.

If you don't already own a BC and are looking at doubles, the a backplate and wing is your primary option since it's difficult to mount doubles on a traditional jacket type BC. Then, look at what you're doing it for and what you'll be doing in the future. If you only plan on doing rec dives then you don't have to worry as much. If you think you may do deeper or decompression dives than you'll have to worry about additional tanks which are additional weight.

 

[TeddyDiver]

Theres some more factors too. The main consideration would be the total weight and total volume including You and all the equipment you dive with. Having thicker exposure suit increases your boyancy and on the other hand steel botlles generally decreases it, but necessarily steel doubles doesnt need high volume BC. Do Your homework and test and calculate everything!

By the way, Im doing my IDC here in Phuket right now and enjoying every minute:10:

 

[Diver0001]

Many recreational BCDs have 16-17kg lift capacity.
If the stucture of the recreational BCD backplate is reliable,
that means could I mount 2x15litres on the BCD? (usually they weight in the water 12kg together) and avoid the purchase of a technical bcd. (Just in terms of lift capacity)

A bcd with a plastic backpack would fall to pieces with a double 15. In the water they might weigh 12kg but out of the water they weigh more than 40. It's just a matter of time before either the backpack or the stitching or both start to separate.....

And there must be a reason for carrying twin 15's. Chances are you don't want your bcd to fall apart under water either.... after all, it's still 12kg.

The heaviest twin-set I think works OK on a "normal" jacket is a twin 7. It just weighs a little more than a single 15 and will give you redundancy if that's what you're looking for.

The lift thing is also a factor to consider. Your BCD should be able to float all of your gear, tanks, regs, weights etc on the surface. Ideally, you'll have a little more than that too to keep you on the surface in heavy seas or when helping out your buddy etc.

With those tanks, I would think 20-25kg is the minimum you should be looking at.

R..

 

[seatrek]

Many many thanks for your info.

 

[String]

my wing rated at 22kg provides me with more than enough lift and ive seen people dive with twin steel 12s and 2 7l stages on this setup and still be ok. You dont want TOO much life, you want adequate lift.

--

and FWIW ive seen twin 12s used very regulary on standard buddy commando BCs with the ABS backplate, in some cases for years with no faults..... and on the flip side my poor build quality Mares backplate snapped with a single 15 and pony.