Posted by Eins on July 12, 2002 at 21:36:45:
In Reply to: Re: Bzzzz.....Sorry. We have some lovely parting gifts for you at the door. posted by Ed on July 12, 2002 at 15:26:36:
Kendall could probably put this nicer, but I think you are still not getting it.
Once a diver is neutrally buoyant in water, YOU KNOW THE PRECISE AMOUNT OF DISPLACED WATER by simply weighing this diver with all his (dry) gear. His weight in kg equals the amount of liters of fresh water or the amount of salt water minus 2.5%. So, why do you want to do your pool measuring stuff?
Let's make this transparent for you.
Let's say our diver, with all his gear including weight belt, has a dry weight of 280 lbs which gets him neutrally buoyant in salt water.
(280 lbs = 127 kg = 124 L of salt water displaced, but you don't really need all these numbers).
To get him equally buoyant in fresh water, you take off 2.5% of his total weight.
280 lbs - 2.5% (280-7) = 273 lbs.
He has to take 7 lbs off his weight belt. If that is too simple for you, then I can't help it. Good night, and don't forget to pick up your lovely parting gifts ;-)