Am I missing something?

[Croomrider]

If that is for me, I am really only wondering about the 2.5% of total body weight equaling the fresh versus salt thing. Does that really work for some, regardless of the exposure protection etc?

I know it won't work for me because I don't use weight the very few times I am in fresh water, so this is all news to me. All my weight checks for me and students are done at the end of the dive on an "empty" tank at a safety stop. But then again we start in the ocean, so it's all figured out there.

The 2.5% should only be applied to a total system that is neutrally buoyant at the desired depth in fresh water. You cannot get close by weighing an object like a cube of Styrofoam and adding 2.5% of the weight to get it buoyant in salt water. Conversely, you cannot do it to a hunk of lead either. If you apply it to a diver with all of his gear on, that already has his weights correct for fresh water at the desired depth, you should be able to add 2.5% of his total weight including gear, and be very close for salt water.

Mike