Converting weights from fresh to salt water

[spectrum]

Salt water weighs 64.1 lbs per cubic foot, while freshwater weights 62.4 lbs per cubic foot. This means, when going from fresh water to salt water, the water will be 2.7% more bouyant ((64.1 / 62.4) - 1). Take your body weight, add about 30# for your gear, and add your weights, multiply by .027, and that's how much more weight you should need.

Going from salt water to fresh is the same process in reverse. The water will be 2.7% less bouyant (1 - 62.4/64.1), so you need to take off about the same amount of weight.

To fine tune than and make the math easier try multipying by .03. The added weights will also displace some water negating some of their actual weight.

 

[Scubamedicjoe]

my guess would be 4-6 LBS

 

[timz]

Hi... sorry to revive an old topic.

My camera system weighs 6kgs on land using my baggage weigh.

fully submerging it into freshwater, it weighs 1.6kgs with no float arms.

However, I borrowed 2 INON M megafloat rated +650g buoyancy underwater and installed them. Now it weighs -400g to -500g.

Do you think the system will be positive in saltwater?. Cause i want my system to be slightly negative.

 

[TMHeimer]

The best way to determine weight requirements is to get in the water and do a buoyancy check...That is really the only way you are going to know for sure.

Yes.
I rarely dive fresh water, but use 5 or 6 pounds less than for salt--depending on which is easiest and better for trim, which pockets I have available, etc. One pound either way won't matter.