RE: [PSUBS-MAILIST] About snorkels.

There are some different issues to consider when developing a snorkel for a 1 atmospheric sub as compared to an ambient. Doug has given some great forethought and has solutions for many of the issues tied to ambient ops. A snorkel that is jammed shut by submergence will quickly suck the air out of an ambient sub resulting in a partial or complete flood depending on the airspace configuration. Water induction into the engine while running will result in cracked heads in a diesel and lesser damage in a gasoline-fueled engine (the valves lift, relieving pressure).

The one over riding consideration for 1 atmospheric submersibles is that more subs have been lost in peacetime (and nobody really knows how many in wartime) due to snorkel/induction trunk system failures than any other means for failure. Due to the large diameter necessary to provide the high flow of air that a diesel uses, flooding is very rapid as a result of a failure. A momentary submerged snorkel can result in inner ear damage and a variety of other maladies. If the exhaust is open while underwater (at least at shallow depths), the positive pressure of the exhaust limits the ingress of water. Much more thought has to be given to 1 atmospheric sub snorkel systems.

R/Jay

Respectfully,

Jay K. Jeffries

Andros Is., Bahamas

It is the mark of an educated mind to be able to entertain a thought without accepting it.
- Aristotle

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Joseph Perkel
Sent: Sunday, February 25, 2007 7:58 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] About snorkels.

Regarding snorkels, when I was contemplating the ambient war-boat replica. I was following closely what Peter Madsen was doing with Kraka.

He had changed things a bit from one type of float valve to another. Since this was his second boat with a snorkel and a third revision, I took notice but, Kraka of course, is 1 ATM.

Doug's version is also really very clever, just let it drain into the space, then bilge pump it out, basically, don't worry about the snorkel. 1 ATM though, has to seal it but, a clever scheme for an ambient compensated space.

Also, for anyone contemplating diesel exhaust, Peter's exhaust chamber in the aft part of the Kraka's sail, is ingenious.

Joe

From:  James Huffman <grandadmiraldonitz@yahoo.com>
Reply-To:  personal_submersibles@psubs.org
To:  personal_submersibles@psubs.org
Subject:  Re: [PSUBS-MAILIST] About snorkels.
Date:  Sat, 24 Feb 2007 20:31:59 -0800 (PST)

Very interesting. I have a couple of pics that deal with the snorkles used by the kriegsmarine. One can find them at www.uboat.net It is a good site.





James



djackson99@aol.com wrote:





Frank

That is very close to what I actually did. I first considered keeping the snorkel sealed and dry when submerged, but letting it food eliminates the possibility of a valve failure from rapidly throwing off the trim, and because I don't need the additional displacement. Instead of a check valve in the bottom of snorkel I used a direct acting solenoid valve and it is mainly going to be used to flood the snorkel.

It's important to flood the snorkel as the

sub submerges, otherwise I would have to flood my variable tanks sufficiently to compensate for the displacement of the air inside the snorkel and then when the intake at the top of the snorkel finally allowed the snorkel to flood, I would be very quickly be too negative in the aft. Also without water in the snorkel, no ambient pressure would build in the engine compartment as it submerges and so the water rushing into the snorkel would also partially flood into the engine compartment.

I also put a bilge pump connected to the bottom of the snorkel to help dump water when surfacing as well and a gauge to indicate the water level so I can make sure to prevent flooding in the engine compartment. It's a confusing photo but here the bottom of my engine compartment. The solenoid valve is

the brass part beside the jet pump intake. http://www.submarineboat.com/sub/images/engine_comp_bottom.JPG

There is a very long winded explanation of the whole mess on this page if you drop down to "Engine Compartment" http://www.submarineboat.com/sub/engine_drive.html

--Doug J

-----Original Message-----
From: ShellyDalg@aol.com
To: personal_submersibles@psubs.org
Sent: Sat, 24 Feb 2007 7:34 PM
Subject: Re: [PSUBS-MAILIST] About snorkels.





Would a p-trap arrangement with a one way valve to dump the water out the bottom work?



When

you submerge, the water pressure would keep the valve closed, and when you surface, the weight of the water inside the snorkel would open the valve and let the water out.



A light spring would keep the valve closed when you have the motor off and begin to submerge, while a poppet valve at the top of the snorkel would keep most of the water out. Then, when you come up, any water in the trap would leak out through the trap valve. Frank D.



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