T-Pain Is On A Boat: Re: [Electric Boats] Re: new member, bruce

Saturday, July 26, 2014

Re: [Electric Boats] Re: new member, bruce

Thanks Capt. The Yamaha jet pump impeller is only about 4 in. In diameter. Yes, if I tried to drive My Volvo 15 inch/17 pitch propeller with a 3HP elec motor, im sure it would burn up in short order. My generator puts out 7500 watts so according to the formula of 1HP = 750 watts, i could go as high as a 10HP electric motor. that would still be iffy. im sure the Volvo stern drive eats up about 10HP in transmission losses so it would be a wash.

Anyway, thanks for the response. I'll post pics as I progress.

Bruce

On Jul 26, 2014, at 12:47 PM, "Carter Quillen twowheelinguy@yahoo.com [electricboats]" <electricboats@yahoogroups.com> wrote:

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

On Jul 9, 2014, at 9:38 AM, danbollinger <no_reply@yahoogroups.com> wrote:

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).