weight change fresh to salt and 7mm to skin

[mth1993]

I am diving next week in FL and looking for some advice on where to start with my weights. I dove this week in MI with a 7mm (newer waterproof suit so not very compressed) with 16 lbs and was almost perfect. I had to swim down at first to descend but once below 15' i was great for the whole dive. I did not have much of an issue staying down for my safety stop. In FL I am will not have the 7mm but just a skin. I dive with an AL back plate, 32lb wing, no padding, neutralish fins, 5'11", 215lbs, and in so so shape.

I am going to be fairly shallow 20-40 feet looking for fossils, so I am tempted to be slightly overweight but do not want to over do it. So what should I start my weight at?

I have tried the dive buddy calculator and it said I should have used 24 lbs this week (8 lbs high), add 7 lbs for going to salt and take away 16 lbs for losing the 7mm. which would put me at 7 lbs, that sounds a bit light.

Any advice is appreciated.

Thank you

Mike

 

[decompression]

The only really buoyant things you'll have are; tank (Al 80), salt water and maybe a bit for the skin.
The calculator is right in the ball park. This is how it score it;
Neg- BP, regs, -4
Pos- tank, suit...+5
So you are just a bit positive, account for ocean and bio-prene, 8-10 lbs total, so I'd have 2x 4lbs on the belt and that should be close. I was in key west a couple months ago, I used 12lbs but I was sidemount al80s, rash guard and lots of bioprene.


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[ams511]

I have tried the dive buddy calculator and it said I should have used 24 lbs this week (8 lbs high), add 7 lbs for going to salt and take away 16 lbs for losing the 7mm. which would put me at 7 lbs, that sounds a bit light.

24 + 7 - 16 = 15 lbs. This seems a bit much. I would try 12 lbs first and see if you can remove a couple of pounds.

 

[TotDoc]

I actually think your 7# swing from fresh to salt is a bit high- a good rule of thumb is 1 # per 40# of diver, so 5# should likely be enough. I am 6'3" and 220 lbs, and 5# works fine for me for the salt/fresh swap. If your 7 mil really is 16# of lift, and you only needed 16# to stay down in fresh water, then you may find you only need 5# to offset the change to a skin if you are in salt water. I know you think the 8# sounds light, but don't underestimate the buoyancy of a 7mm! I wouldn't start any higher than 8# - and in fact, you may be able to drop a bit. Another thing to consider - if you are just picking up shark teeth, you won't have much of a buoyancy change, but if you are also picking up larger stuff like manatee bones, you will quickly find yourself overweighted just from your fossil haul. Anyway, best of luck!