Fresh Water vs. Salt Water Bouyancy

[pt40fathoms]

Over time we all get a "feel" for how we should be trimmed, and how much weight we should be carrying, depending on what equipment we have on. Likewise, we soon establish benchmarks that we use as averages. One of these benchmarks is the different amount of weight we will need when diving fresh or salt water.

Being a fresh water diver in this part of the country and having yet to dive in salt water, my best guess for added weight for salt water is at best marginal.

It seems, that after having logged a few hundred dives, I will find myself like a fish out of water (pardon the pun) when I do my first giant step into the salty deep.

So on to the question. What *percentage* of weight should be added to compensate for salt water? I ask for a percentage, as the total amount of weight may change with the equipment used. Is their a standard calculation for this amount of added weight published somewhere?

Underwater "gardeners" need not reply...

 

[Rick Murchison]

Salt water density varies a bit, but on average is 1.025 that of fresh water. You need to add 2.5 pounds for each hundred pounds total weight to achieve the same buoyancy in salt water as you had in fresh.
So if you weigh 190 and your gear weighs 50, you'd weigh 240 total and you'd need to add 6 pounds for salt water.
Rick

 

[metridium]

pt40fathoms wrote...

Underwater "gardeners" need not reply...

How about one-time underwater amateur geologists?

Started out with more than doubling my freshwater ballast (18lbs vs. 8lbs) on a recent saltwater dive with similar equipment. Wasn't enough...that was one ugly dive.

Added another 6-8lbs on the next series of dives for a much more enjoyable experience. Not sure how much of that I could have trimmed off eventually...