Salt Water Compensation

[bge123]

I have recently lost some weight (i.e. fat) and now when I dive in the local quary in a 3 mm 1 piece wet suit, I am now using 4 lbs of weight to get down. I dive a single tank, Scuba Pro Maverick BC, etc...so nothing special there. In the dive pool, with no wet suit, I use no weight.

I am 6'1, 180lbs.

That is the set up, now I am headed for warm salt water (Carribean) for three days of diving. How much (if any) additional weight should I plan on for the first dive? Once that is done, I will know more, but want to be close on the first if I can.

Thanks!

 

[diver 85]

What kind(al vs steel & size) of tank are you using locally & what kind are you expecting to use in salt water(most use Al 80's down 'south').......

 

[spectrum]

Take your total diver weight (you suit, tank, weights, the whole dry pre-dive deal) and divide by 40. 6-8 pounds extra for most folks.

Pete

 

[jonnythan]

Add 5-6 pounds and you should be good.

That's not arbitrary though. You want to take your total "in the water" weight and multiply it by .025 to get the additional weight you'd need for salt water, since the salt water you're displacing will weigh 2.5% more than fresh water. 180 + ~40 lbs of gear is 220. 2.5% of 220 is about 5.5.

 

[Rainer]

If you can get your full gear that you'll be using into the pool before the trip, you just add 1# for every 40# of diver+gear for going from FW to SW.

 

[bge123]

Will be AL-80 I'm sure.

 

[don Francisco]

All the answers are about right, but Spectrum gave you the exact conversion. Salt water is 2.5%denser than fresh so assuming you're correctly weighted and your displacement equals your weight, either add or subtract 2.5% of your TOTAL weight - you, your suit, your equipment, and your weights - to convert from fresh to salt water and back.

 

[Charlie99]

Will be AL-80 I'm sure.

If that's the type of tank you used when checking your weighting in freshwater, then life is easy.

As others have noted, provided you are using the same wetsuit and tank then the adjustment when going from freshwater to saltwater is to add about 6 pounds.

The theory behind this simple recommendation is that saltwater is about 2.5% more dense than freshwater, so adding that percentage to your total dive weight keeps you neutral. The reciprocal of 2.5% is 40, so the other way of saying the same thing is "add 1 pound for each 40 pounds of total dive weight, including all gear including tanks and lead".

You are 180 pounds. Your tank is about 35, your other gear (regulator, lead, wetsuit, BCD, lights, etc.) is maybe 25 pounds, for a grand total of 240 pounds. Work the math and you get 6 pounds.

 

[bge123]

So if in fresh water, w/ my same gear, I am negatively bouyant with zero pounds, how would measure that weight?

 

[Rainer]

how would measure that weight?

Stand on a scale.