----- Original Message -----
Sent: Wednesday, March 01, 2006 10:01
PM
Subject: Re: [PSUBS-MAILIST] ambient
ballast control
When I dive Persistence, I dive it neutral
buoyant. There is an additional safety factor if you dive slightly
positive but you can't stay in position near the bottom without
constantly fighting the lift. If I want to ascend quickly without
electrical power I just give a short burst of air into any of the ballast
tanks. Normally I descend and ascend with thrusters.
Once, I let someone dive solo in my sub. He
was familiar with the sub but I coached him through the diving sequence from
topside on the radio anyway. I had him set about five pounds
positive. It was relatively shallow and he couldn't get into much
trouble being positive buoyant as R/Jay mentioned.
If you were fifty pounds positive, I doubt you
would be able to get your sub to submerge. Fifty pounds of downward
thrust is a lot to generate! There is a lot of mass to the sub so things
happen slow but five pounds heavy or light will make the sub move up or
down nicely. Ten pounds moves you a little faster. If you were
only going thirty feet to the bottom five pounds is enough. If you were
going two hundred feet down, more weight would get you there
faster.
Your ballasting system doesn't have to be able to
adjust a lot. I move lead weights in and out depending if I have a
passenger and how much they weigh. I have 20 LB, 10 LB and 5 LB
weights. A total of about 400 Lbs. of lead. My variable
ballast tank is only about 35 pounds in total.
My favorite way to dive is neutral and drifting a
few feet above the bottom. It's really quiet when the sub is drifting
and only powered once in a while.
Dan H.