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Alec, I agree with that, the idea was one I had early on, long be for I bought the sub, and I'm not thinking about that configuration now. I would of been alone the line of the S-101 decks and fairings, but not near as long of course. The front and rear decks and fairings would of likely been about the same size as the rear canoe fairing that is on the Trilobite K-250 currently. But with the rear section cut short to allow for a small transom for the outboard. When I first saw the long rear canoe fairing that is on the Trilobite K-250 now, I thought is was the rear MBT. So I was looking at how one could configure a MBT like that and not have the air bubble traveling back and forth when it's partly filled. I was thinking that if one wanted to make a front and rear MBT like that, that you could divide it in two length wise with a baffle, and perhaps cap most of the bottom area. Then have air inlets and outlets on both sections, that can be operated independently from each other. In this configuration there would be more air in the bow and stern to hold up more weight. Perhaps enough for some people to stand on. This makes me think that perhaps instead on encasing a outboard motor that is mounted on the very aft of the sub, that one could encase a similar sized gas generator motor and mount it submerged just behind the rear head, half way down or even lower, with it's snorkels coming out above deck. This would keep the weight a lot lower and closer in the the subs CG. Then that can power your existing electric thrusters when running on the surface. Now that I think about that more, I might like to add that to my sub if I can make it small enough. I am planning to switch out some external lead for more internal batteries like you mentioned, and I plan to have a foot taller conning tower with a metal hatch on top of it. So my metacentric height will change some. So to better deal with that, I plan to install inflatable pontoons for mostly surfaced stability. If you go stand on the end of your rear MBT, can I film it for youtube? ;)' Regards, Szybowski Subject: RE: [PSUBS-MAILIST] Lifting K-250 Off Trailer the Hard Way Date: Wed, 10 Dec 2008 10:37:47 -0500 From: Alec.Smyth@compuware.com To: personal_submersibles@psubs.org Brent, bear in mind that even if you do put flat decks over the MBT's, a K250 is just too small to go for much of a walk. I'm skinny, but I have the impression if I stood on the end of a MBT while surfaced it would stand the boat on end way more than I'd be happy with. Even opening the hatch alters the trim a little, due to the hatch weight being over the hinge instead of centered. I'm not saying the K250 isn't admirably stable when everyone is sitting in the right place, it is. But if you move around, the boat does too. And I recall you mentioning you might ditch those low-down lead weights on the skids in favor of some not-quite-so-low extra batteries in the cabin.
:)
Alec The contents of this e-mail are intended for the named addressee only. It contains information that may be confidential. Unless you are the named addressee or an authorized designee, you may not copy or use it, or disclose it to anyone else. If you received it in error please notify us immediately and then destroy it. From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent Hartwig
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. Sent: Wednesday, December 10, 2008 00:58 To: PSUBSorg Subject: RE: [PSUBS-MAILIST] Lifting K-250 Off Trailer the Hard Way 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. |