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Re: [PSUBS-MAILIST] x303



David,

When sizing engines for "displacement" hulls, a rule of thumb formula is 1.5 x (per ton), to arrive at HP required to move a vessel to theoretical hull speed. Therefore for a 3k displacement, 1.5 ton x 1.5 = 2.25 hp. This rule of thumb can be confirmed by perusing various vessel design sources.

If I recall correctly, the aft thruster on the Kittredge boat is 3 hp for a 3800 lb boat.

Here is a link for super efficient sizing for solar powered vessels, not quite applicable to submersibles (with appendages), but is an interesting process for sizing thier motors and battery requirements.

http://www.solarnavigator.net/hull_drag.htm

Joe


From: "Dan H." <jmachine@adelphia.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] x303
Date: Mon, 16 Oct 2006 22:05:03 -0400

David,

You might want to rethink that 50 HP motor. If you have only one prop with all that power, won't you send your sub rolling through the water in the opposite rotation of the prop? Two opposite rotating props would fix that, but still, that's a lot of HP.

With a sub your size, you'd fly thought the water with 15 HP. Submerged, you have to be in pretty clear water to use 5 HP.

Just a thought, Dan H.
  ----- Original Message -----
  From: DrewBane1@aol.com
  To: personal_submersibles@psubs.org
  Sent: Monday, October 16, 2006 4:22 PM
  Subject: [PSUBS-MAILIST] x303


  is this e mail going thru?


      Hello everyone,
Just wanted to introduce myself, my nave is David and I work as a Industrial fiberglass technician in Wilmington DE. For years I contemplated building a small submersible capable of carrying two people to a dept of 130'. Recently I decide to go ahead and start building my sub. It will be quite a challenge. The sub (X 303) will be built in 4 module sections 24" in dia and a total length of 20'. The sections will be fabricated from 3/4" FRP which will bolt together internally and will displace approx 3,000 pounds. Power will be derived from a 50 hp 2cyl engine thru a 2:1 gear reduction driving a 14" X 13p propeller. A marine alternator will be coupled by belt to the engine to recharge the gel cell batteries. I have begun constructing the bow/ forward ballast compartment and hope to complete this section by months end. I have laid up the bow sections and joined them to a 24"l section of pipe next is to lay up the 1 1/8" internal flange and join it to the bow section then overwrap the whole bow/ballast section to build up to the 3/4" thickness I am looking for. more pics to come





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