double tank weighting issue?

[simcoediver]

I have recently transitioned to diving double steel 72,s and have found that my weighting is perfect with just an aluminum backplate and wearing a 3mm wetsuit, in otherwords I have no ditchable weight at all !I can swim up easily with this setup. I was just wondering if other divers have this situation where there is no ditchable weight and if they think this is safe?
I do normally wear a drysuit and do have ditchable weight for that.

 

[Meng_Tze]

I have recently transitioned to diving double steel 72,s and have found that my weighting is perfect with just an aluminum backplate and wearing a 3mm wetsuit, in otherwords I have no ditchable weight at all !I can swim up easily with this setup. I was just wondering if other divers have this situation where there is no ditchable weight and if they think this is safe?
I do normally wear a drysuit and do have ditchable weight for that.

You have the answer. But let me turn the question around.............why would you need ditchable weight? What does it address?

 

[simcoediver]

Ok, thanks for the clarification, I just thought that some ditchable weight was always required in the event of an emergency situation perhaps on the surface?,maybe that is the PADI OW training from years ago kicking in.
I guess its fine then as my weighting is perfect so nothing to worry about.

 

[Jim Lapenta]

Ditchable weight? Yep, I ditch it before I get in the water by leaving it in the car for those who might need it.

 

[lowridersvt]

there is no reason for ditchable weight in a doubles set up . as long as its a balanced rig

But you should have 2 types of boyence control even if you can swim you doubles up you have to be able to hold a stop .

so either a lift bag with near the same lift as you bc

drysuit

Or a double bladder wing

 

[MattL]

all so you need to do a test to make sure your have right about of waight if you can hold a 10 ft stop at 300 to 500 psi with no air then your good just rember that a full set of buds your have 15 ilbs or more of wahgt in air

 

[DA Aquamaster]

Matt is on the money with the swing weight issue. Given that you have twice the gas whihc weighs twice as much, if you are doing the samesingle tank dives you always did and are coming back with half full tanks, you may not realize if you are underweighted until you get in a situation where you are down to 300-500 psi and disvoer you are no longer neutral but maybe 5 pounds positive. That can be a real problem when you are in deco and do not have an anchor line available to help hold you down.

Ideally you should be neutral at 10-15 feet with no gas in the wing and 300-500 psi in the tanks. In a wet suit that will normally leave you very slightly positive on the surface (floating about eyeball level with full lungs and sinking slightly when you exhale.)

In the event you need to add weight, a V-weight or a tail weight (depending on trim requirements) is a better and more streamlined way to do it than adding ditchable weight.

 

[simcoediver]

Thanks everyone for all your info, da aquamaster, if I find that I need to add weight I can simply switch to my SS backplate, but the way it is set up now is right on with the Al backplate, Im going to do some more practise in the pool to make sure Thanks

 

[Flightlead]

a bad situation to be in is when you are positively buoyant with bingo air, in an air sharing situation, and have some deco obligation. how are you going to stay down?

I have actually been struggling with this weighting issue for about 9 months now. with steel doubles, al backplate and 7mm suit (summer wear) and the same doubles, steel backplate, drysuit (winter wear). I have come up with a design for a modular set of lead weights that sit behind my plate and let me adjust weight in 5 lb increments to allow for a variety of situations, trim requirements, and which are firmly mounted and easy to adjust. I have the plaster of paris male moulds hanging in the garage right now, will be making my female moulds this week and hope to cast my prototypes as soon as this weekend.

 

[DA Aquamaster]

Stacking two plates or going with a heavier plate like those sold by Fred T are other options to add weight. But V weights are comparatively inexpensive and have the benefit of being easily removeable.

This can be an advantage if you switch from a 3mm wet suit or dry suit with very light undergarments for a Florida cave dive or warm water wreck dive and then the following week find yourself a dry suit with heavy under wear for a cold North Atlantic wreck dive. It can be nice not to have to change plates or buy and configure a separate harness and plate.