Doubles and weight requirements

[stas]

Hi,
thanks for all the replies.
My current setup is dui cf200 drysuit, lp125 tank with Y valve (so I already cary two regulators), a steel backplate, can ligth (its a green force unit with a big lighthead so I think its slightly heavier then regular can lights) 14 lbs on my belt. Those peole who say they are to negative without extra weights, are you using steel or aluminum plates?

My concern is that I will be negative with full tanks and no weights but will need some weights to compensate for air (meaning I will pecome positive after some air is consumed). In this scenario, my plan of blancing my rig with full tanks and then adding the compensating weight won't work.

Stas

 

[theskull]

You're doing way too much math and theory work.

Just throw them on (wearing an empty weight belt with weights handy--preferably attached to your buddy) and start diving them.

Do easy shallow dives so unplanned buoyancy problems are just an annoyance rather than a safety issue and learn in real life how much weight YOU need while wearing YOUR tanks and rig in YOUR exposure protection. Make sure you make some of these "test" dives with little pressure left . . . say 500-700 psi so you can be sure that you can remain neutral at a safety stop with the least amount of gas weight that you will expect to dive with realistically.

theskull

 

[do it easy]

Those peole who say they are to negative without extra weights, are you using steel or aluminum plates?

I don't wear any weight in freshwater with my LP95 doubles and a steel backplate. I could probably switch to an AL and be fine. Then there are some dives with lots of bottles that feel like am wearing a boat anchor.

I suspect that your weighting won't change much since you already have most of the gear on already with 14 lbs of weight. You would be adding a manifold, bands, and a tank which would be near neutral when empty. My guess is that you'll end up around 10-12 lbs, assuming you are properly weighted now with 14 lbs. Use theskull's scientific method to find out.

 

[Packhorse]

I use 2 11.6 liter(115cf) Asihi tanks for my doubles . they weigh 15.7 kg each.
I seem to be perfectly weighted with them, an ali plate and my 6.5mm wet suit.

the best way to work it out is to dive it and see.

 

[rawls]

What is weight?

 

[do it easy]

I think weight is a measure of the magnitude of the effect of gravity on mass.

 

[KOMPRESSOR]

You're doing way too much math and theory work.

Just throw them on (wearing an empty weight belt with weights handy--preferably attached to your buddy) and start diving them.

Do easy shallow dives so unplanned buoyancy problems are just an annoyance rather than a safety issue and learn in real life how much weight YOU need while wearing YOUR tanks and rig in YOUR exposure protection. Make sure you make some of these "test" dives with little pressure left . . . say 500-700 psi so you can be sure that you can remain neutral at a safety stop with the least amount of gas weight that you will expect to dive with realistically.

theskull

Thank you! My idea too. Keep it simple!!!

Skip most of the heavy calculations and find out in a practical way just how little lead you can stay down with at ten feet, preferably with a little squeeze in your dry suit, and with nearly empty tanks. Then the weight of gas will only make you heavier than this on all dives thereafter.

There are alu-plates, steel plates, alu-tanks, steel tanks, heavier steel tanks, cannister lights with NiMh batteries and with acid-lead batteries. Then there are undergarments with loads of bouyancy, and thinner more compact stuff that still keep you warm. Just make sure you are using what you normally would and don't poke around to much with different riggings.

I could tell you just how little or how much lead I'm using with my doubles, but it wouldn't be of any value for you to know this, so I won't this time...

Good luck with getting it right! It's really not very difficult, as long as you're not totally helpless with your BOUYANCY CONTROL.

 

[Dive-aholic]

Hi,
thanks for all the replies.
My current setup is dui cf200 drysuit, lp125 tank with Y valve (so I already cary two regulators), a steel backplate, can ligth (its a green force unit with a big lighthead so I think its slightly heavier then regular can lights) 14 lbs on my belt. Those peole who say they are to negative without extra weights, are you using steel or aluminum plates?
Stas

2 lb aluminum and still heavy in my cf200