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Frank, Before I knew my sub was built by the Captain, I was thinking of changing both MBT's. The bow would be more of a wave piecing shape for better towing and the rear would go out a bit further and have a flat deck so I could bolt a outboard motor on a small transom and be able to get to it when the sub was surfaced. The outboard would be encased by a small SS housing so I could dive with it. Fuel would be in a external fuel bladder. My friend that makes SS tanks for a living would proof my design, and fabricate it. It would be nice if I could run the outboard with the main pressure housing submerged, and then have snorkel tubes for the engine air intake, housing breather intake and exhaust, and the main exhaust. This way I don't have the weight issues of having the weight of most of the assembly above water when surfaced to deal with in moments calcs. In that configuration I would need a unlock able hinge assembly with gas shocks or springs to allow me to lift the motor housing out of the water when at the surface, so I can monkey with the motor. I was thinking of using a internal locking ring design for the front and rear ends of the pressure housing for easy access and less hydrodynamic drag. A simpler locking means might work just as well, if I use large soft O-rings. I'll have to work up a CAD model and show you exactly what I'm thinking. I still want a wave piercing bow for towing, so I'm working up a design for a extra FRP fairing I can easily attach for towing ops, then then remove before diving. The trick is figuring out an easy attachment means. Regards, Szybowski From: ShellyDalg@aol.com Date: Tue, 9 Dec 2008 20:50:01 -0500 Subject: Re: [PSUBS-MAILIST] Lifting K-250 Off Trailer the Hard Way To: personal_submersibles@psubs.org Jim/Brent. I can't see the need to calculate battery usage at full power. Surface travel is the most likely place for full power usage, while submerged travel is usually done at much less. I plan on using an outboard motor for most surface travel, and then bringing the small outboard either inside or loading it onto a surface boat while diving. Again, using a larger motor at slow speed is more efficient than using a smaller motor at full speed. The prop losses are a large part of that equation. Bigger prop turning slower is way better. Frank D. |