Bruce,
I'd make the cog on the motor as small as you possibly can, like 5-10 tooth, and then reprop with a "SMALLER" prop, like something off a 2-5 hp outboard. This will be your only hope of not burning that motor up the first time you use it.
It will most likely burn up pretty quick anyway but the closer you can match the load from the prop to the HP of the motor, the better your odds. Should be fun to see how it does, sometimes these things will surprise you but don't expect much more than a knot or two in dead still conditions at best and plan on the wind and sea to pretty much have it's way with you.
Good luck.
Capt. Carter
www.shipofimagination.blogspot.com
On Friday, July 11, 2014 7:12 PM, "Bruce Wilder brucewild@gmail.com [electricboats]" <electricboats@yahoogroups.com> wrote:
Hi Dan, thanks for the input, no doubt the tunnel concept as developed in ww2 by Higson for the landing craft is the best way to go. However I have my hull built and am committed to the outdrive for primary thrust. Yes, axial jet pumps are way inefficient but all I need is a few knots. I wouldn't dream of economical cruising with a jet. Well ask said in previous post, this is all experimental and I'm not out much money if it doesn't work. Stay tuned.
Bruce
An Archimedes screw is a pump, not a prime mover. From what I understand, such a screw will not have better performance than a prop of the same diameter. I will say that a prop in a tunnel hull can work to reduce operational draft, but it is less efficient than a prop mounted outside the hull, but I think better than a axial impeller (jet drive).
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Posted by: Carter Quillen <twowheelinguy@yahoo.com>
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