Fresh water weights v.s. salt water weights

[sam1]

Salt water is about 2.56% (=64 pounds per cubic foot/62.4 pounds per cubic foot) denser than fresh water. With you weighing 230 pounds, plus 25 pounds of lead, plus, say, 40 pounds of tank, plus 5 pounds for other stuff to give us a round 300 pounds, you would need nearly 8 pounds additional lead for salt with the same gear and exposure protection. If everything is the same except for the exposure protection, we need to adjust for that. Rule of thumb (for amount of lead needed):

3MM, one piece wetsuit, shortie or jump suit
5% of your body weight

7MM, cold water wetsuit, hood and boots
10% of your body weight plus 3 to 5 pounds

So to go from 7mm to 3mm (assuming you were wearing a hood and boots) we need to subtract 5% of your body weight plus 3 to 5 pounds, i.e., 15 to 17 pounds.

So, add 8 pounds for salt, subtract 15 to 17 pounds for the change in exposure protection equals minus 7-9 pounds. So, if you are using 24-26 pounds now, your ballpark for salt and 3mm is around 15-19 pounds of lead.

 

[StuartT]

5mm full wetsuit with aluminum 80 for me= 16lbs weight in salt water
3mm neoprene drysuit with 130 steel (-11.7 full)=24lbs in salt water I will be adding 2-4 lbs to this so I can put more air in the drysuit for added warmth. Got a bit chilly in September in 46-48 water with 24lbs.

 

[dumpsterDiver]

12lbs- I think you are way off there. 12 won't get me down at all.

I'v been a divmaster for many dives. I've supervised 100's of divers who have no clue how much lead to use. I knw what I am talking about. 12 lbs is close to what you will need, if not come back and tell me how much I was off and I WILL mail you the exact pounds of lead extra that you needed above 12 lbs FOR FREE!!!!! Seriously

chances are, you will need around 9 lbs, but 12 is a good place to start experimenting.

 

[Paladin]

I'm 6' 1" and at 230 lbs, with a 3mm fullsuit and an AL80 tank, I need a minmum of 16 lbs in freshwater. Any less and I have to fight to get down with a full tank and as the air is used up, I become too light to stay down. With a steel 72, 12 lbs is the minimum, but 14 is better. With my double 72s, 6 pounds of lead is optimum. If I were to try diving is saltwater with only 12 pounds of weight and an AL80, I would never leave the surface.

 

[knowone]

Twelve kilograms.

 

[knotical]

If you can get to a pool before your trip, get in with a nearly empty cylinder (say 400-600 psi) and the equipment you will wear in salt water. Completely empty your BCD and find the minimum weight you need to submerge (don’t forget to relax, exhale, and do not fin). That’s all you should need in fresh water with that setup. Let’s say that’s 6 lbs. Weigh yourself and all the equipment you will use. Let’s say that’s 280 lbs. As sam1 above suggested, add 2.5 – 3% of that 280 lbs. In this example, you’d add about 8 lbs for a total of about 14 lbs.

some caveats:
You should use the same type of cylinder you’ll use in salt water. If in doubt, probably an aluminum "80".
Work all the trapped air out of your wetsuit before the test of submerging with a nearly empty cylinder.

Good luck, and enjoy yourself.

 

[rk288]

I'v been a divmaster for many dives. I've supervised 100's of divers who have no clue how much lead to use. I knw what I am talking about. 12 lbs is close to what you will need, if not come back and tell me how much I was off and I WILL mail you the exact pounds of lead extra that you needed above 12 lbs FOR FREE!!!!! Seriously

chances are, you will need around 9 lbs, but 12 is a good place to start experimenting.

I'll second that...