Re: Drop Weights

[Ray Keefer <Ray.Keefer@eng.Sun.COM>]

Hi,
 
> In all this discussion of ballast tankage, I haven't seen much mention of
> Drop Weights. Is anybody using any form of expendable ballast? 
> ....
> you're going before you start. The task is a bit easier if you're clever
> enough to come up with a shot hopper sort of device that dribbles out bits
> of weight. :-o Joe

My concerns are that one would be littering the ocean floor with ballast. Also
if over delicate coral formations you can actually damage them my dropping
ballast on them. Otherwise it can work.

If your submersible is a wet or ambient design, the important part of using 
drop ballast to surface is that you don't drop too much ballast at a time and
as you surface and expanding trapped air bubbles are controlled. Else you 
will surface at an acellerated rate due to the expanded air bubbles creating
even more positive bouyancy. 

Even more important in ambient designs is not to surface any faster then
60 feet/minute and to breath. If at depth you take a breath and forget to
breath or surface too fast then the air in your lungs will expand and rupture
your lungs. Much like an over filled balloon.

60 feet/minute also allows your body to out gas a some of the nitrogen that
your system had absorbed thus lessening the change of getting bent.

Regards,
Ray