A normal surfacing evolution is accompllished by powering to near the
surface and them blowing main and trim ballast tanks thus conserving the limited
supply of air carried aboard. Only in an emergency are main and trim tanks
blown at depth (and then dropping the emergency weight if
neccessary).
R/Jay
I might add that Jay's point be well taken. Boyle's Law will put
anyone who blows a tank u/w in shallow doo-doo, especially in an ambient
boat. Dropping a CONTROLLED amount of hard ballast will assure a
reasonably safe ascent.
If you can run with a snorkel you can use blowers or bilge pumps to
preserve your air as Jay mentioned.
Rick L
----- Original Message -----
Sent: Wednesday, March 01, 2006 7:25
AM
Subject: Re: [PSUBS-MAILIST] ambient
ballast control
Typically the main ballast tanks should be flooded fully and the flood
valves at the bottom of the tank left open (or in the case of a K-250, the
bottom of the tanks are open). To dive the hard (rated to max. pressure
sea and/or blow system failure) is then flooded to get either neutral or
slightly positive trim. Submergence is accomplished with dive planes and
drive down with the main motor(s) (and in the case of a K-350, additionally
using the auxilliary motors). Being slightly positive will benefit in
the case of a loss of power as the sub will slowly return to the surface on
its own.
A normal surfacing evolution is accompllished by powering to near the
surface and them blowing main and trim ballast tanks thus conserving the
limited supply of air carried aboard. Only in an emergency are main and
trim tanks blown at depth (and then dropping the emergency weight if
neccessary).
R/Jay
-----Original Message-----
From: "Dan H."
Sent: Mar 1, 2006 8:39 AM
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] ambient
ballast control
Joe,
What I was questioning is the need for a pressure
relief in a closed ballast tank where the tank is built strong enough to
withstand the system pressure. If your tank is strong enough to
withstand the system pressure, then it won't blow.
As was pointed out to me by Jay, it's still
possible to get a regulator failure, and unless the ballast tank was built to
SCUBA tank pressure, it could possibly be ruptured if that happened.
Good point. My sub is a one atmosphere design.
That is the one scary thing about an open ambient
sub. Then deeper you go the more air it takes not to go any
deeper. A situation that can be a runaway disaster.
I don't know about an ambient sub, but in my
one atmosphere, when diving, I keep my main ballast tanks totally full of
water , vents opened, and my main ballast tank, adjusted to neutral
buoyancy of the sub and all valves shut.
Dan H.
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