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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