Re: [PSUBS-MAILIST] ambient ballast control

["Jay K. Jeffries" <bottomgun@mindspring.com>]

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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