|
Rick,
Your question is kind of brief. I assume you
know the difference between hard and soft ballast tanks.
There really isn't much of a relationship at
all. Soft ballast is only used on the surface to lift the sub out of the
water, to gain adequate freeboard to enter and exit the sub without flooding
it. If you have air in the soft ballast tanks when diving, it will
compress and as you go deeper and so you get heavier the farther down you
go. Not a good thing if you ever plan to resurface.
Hard ballast, on the other hand, is as it
implies. A hard, pressure tight, tank that is used to set buoyancy for
diving the sub. Since it is hard, it doesn't matter how much air
or water it contains while diving. Your buoyancy won't change in
relation to your depth.
Your sub should have sufficient soft ballast to
lift the conning tower high enough out of the water for it to be safe to open
the hatch. Your hard tank should be of sufficient displacement to allow
you to make fine adjustments in buoyancy. There is no substitute for the
soft ballast. You have to calculate how much water you have to displace to
push enough of the conning tower to a sufficient height. You must
have enough.
On the other hand, having to little hard ballast
tank only means that you have to do a better job of guessing the proper amount
of fixed ballast (lead weights) to put in the sub before starting your
dive. The more soft tank, the more adjustment you have before you have to
add or remove lead weights. To much hard tank requires to much air
consumption if you need to blow some ballast at depth. For starters, I'd
consider about five gallons of hard ballast.
Dan H.
|