Re: [PSUBS-MAILIST] ambient ballast control

Rick,

Thank you for the input but, I did have to refresh my memory a bit here. Two questions for you then.

1) Do Canadians hibernate in winter? :)

2) Interesting possibility, maybe even as a backup system, but it makes me wonder about, how big of a bilge pump(s) to take how long to drain x volume? In my case, pretty big ones I think.

Thanks

Joe

From: "Rick and Marcia" <empiricus@telus.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] ambient ballast control
Date: Mon, 17 Apr 2006 01:37:22 -0700

Hi, Joe - if you run vent piping from your fore and aft tanks through the snorkel, you can use bilge pumps to "blow" the tanks.

Crack open the vent lines while running decks awash (assuming your snorkel is above water) and run the pumps.

Rick L

----- Original Message -----

From: Joseph Perkel

To: personal_submersibles@psubs.org

Sent: Wednesday, March 01, 2006 10:36 AM

Subject: Re: [PSUBS-MAILIST] ambient ballast control

Jay,

Your answer to my question once about HP tanks on the old fleet boats led me to really dig into those manuals. As a result, this is precisely the the diving and surfacing "evolution" I am mimicking with one addition. I intend to use lp air sourced from the snorkel to surface 'every' time. The hp tanks are backup and mainly for compensation and feed air to the diesel should the snorkel close inadvertently.

In fact, I may get away with not having to use any compensation flow at snorkel depth, just forced ventilation...I'm not sure about that yet.

Thanks for leading me in that particular direction.

Joe

From:  "Jay K. Jeffries" <bottomgun@mindspring.com>
Reply-To:  personal_submersibles@psubs.org
To:  personal_submersibles@psubs.org
Subject:  Re: [PSUBS-MAILIST] ambient ballast control
Date:  Wed, 1 Mar 2006 09:25:50 -0500 (GMT-05:00)

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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