calculate weight?

So I am sure this has been covered a million times but I have one question. When I an trying to dial in my weights for ocean diving but I am doing it in a pool do I add just 5 lbs to my belt. Everything I have read and hear says add 5lbs from fresh to salt water.

It may be a good enough starting point, assuming you aren't exceptionally large, diving doubles and/or otherwise notably outside an average weight of a fully geared up diver, though you'll want to do a proper weight check when you're actually in salt water for sure.

You (and everything else) are about 2.5% more buoyant on salt water vs fresh. Which means you need about 2.5% extra ballast (of your total weight - all gear, everything) to sink compared to fresh.

for example
body weight = 170
BC, tank, reg, and anything attached to your BC = 50 lbs (obviously if you're diving doulbes, you'd have much more weight here)
Everything else - fins, exposure protection, gloves, - obviously alot of room for variation here - but lets assume a thick wetsuit and round up = maybe 10 lbs
Weights already on a belt - 20 lbs maybe (for that thick wetsuit)

= 250 lb total weight on dry land. If perfectly neutral in fresh water, you'd need an extra 2.5% of ballast, 6.25 lb, for salt water

---------- Post added May 6th, 2014 at 12:06 PM ----------

for a point of reference, the above stats are pretty close to my own. I use about 6 lbs more in salt for otherwise identical gear with a 7mm wetsuit (with hood + gloves).

Thanks for the lesson on that. I will go mess around with it this weekend.

I add 5 or 6 pounds, but it's been years since diving fresh water. Of course you'd have to be wearing the same wetsuit & tank in the pool to do this as I'm sure you know.

I am 250# and i use 8#extra ballast with a shorty suit. My rig is about 60# so that makes me about 320 geared up. .25% works for me.

I do a weight check at the beginning of my first dive in new surroundings.
get as much air out of the wet suit as possible, try how much lead it takes to sink when exhaling completely and then add the weight of gas in lead.
This will get me slightly overweighted for my first dive and I can correct this by doing another weight check at the end of the dive.

I found I used exactly the same weight on Bonaire with no neoprene as I do in central New York with all my layers of neoprene. You have to estimate for the first dive then dial it in at the end of that dive. That's partly why you do a checkout dive. The other part is to make sure that all equipment is functioning properly after travel.

Kharon:

I found I used exactly the same weight on Bonaire with no neoprene as I do in central New York with all my layers of neoprene. You have to estimate for the first dive then dial it in at the end of that dive. That's partly why you do a checkout dive. The other part is to make sure that all equipment is functioning properly after travel.

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Weird. Have you figured out why the same weight with nothing vs. wetsuit? Can't see how that could be. How thick is your NY wetsuit? Do you use a body suit in Bonaire? In NS I use 35-40 lbs. with 7 mil farmer john and when I was in Panama 10-12 with the body suit. In NY in the summer 18 lb.s with my shorty (all salt water of course).

I did the same thing in fla. i wore a 3mm f j and used X amount of weight. I then went to dive the spiegle grove and went in a shorty that was 9# less lift. Adding weight or removing lift yeilds the same result. With nothing changing but the water I require an 8# change to the negative to go in salt from fresh. All else being the same that requires a weight addition for salt.

How long have you been diving? In local fresh water with under 15 dives I arrived at 18lbs with a 7mm suit. After a few Caribbean dives (with the 7mm- Dec) an old DM salt of the sea type started taking weights out during the dives. I got down to 8lbs! Ok it was a neutral buoyant AL80 and I do have to fin down the first 8' but at my SS I've zero air in my BCD and can control depth by breathing. The error is I believe when doing a buoyancy check as per PADI instructions you end up being overweight. One reason I guess is the wetsuit is bone dry if you need to do a weight check at the start of a dive trip for instance.

I was considering side mount as my back would hurt like hell after a few days into a trip. Now I have no issue even with 2 weeks of diving with HP120 steel tanks.

I have no idea what to use this season up here, but it won't be 18lbs anymore.

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