T-Pain Is On A Boat: Re: [Electric Boats] hull design

Monday, July 19, 2010

Re: [Electric Boats] hull design

Ned, I think you will have to look at a catamaran or trimaran with a very slender center hull. Google "Human Powered Boats" for ideas. There are threads on the boatdesign.net forum that cold be helpful. Search there for posts from Rick Willoughby.

You will not have a high enough power/weight ratio to get a boat to plane in the conventional sense so you are right to look at designs that do not follow the "hull speed" rule.

A Bolger "Sneakeasy" might work; its about the right size. Have you seen the Etec outboard / Sneakeasy by J Rundholm? http://www.psnw.com/~jmrudholm/etekoutboard4.html

He got 10.4 mph at 125 amps, 48v. With 600# batteries duration would be more like 30 minutes, though, not 3 hours. Maybe 600# of LI-ion batteries would hit your range goal.

Good luck

Denny Wolfe

www.wolfEboats.com

----- Original Message -----

From: nedfarinholt

To: electricboats@yahoogroups.com

Sent: Monday, July 19, 2010 3:55 PM

Subject: [Electric Boats] hull design

I am interested in building an electric runabout and would like help on hull design. Here are the basic requirements:
Less than 30 feet in length, preferably 25'
Strip hull construction
Sufficient beam to accommodate two persons side by side, at least 3', prefer 4'
Sufficient stability to handle a broach in 3' chop or powerboat wake.
Prefer monohull.
Cruising speed above 10 knots.
Cruising duration 3 hours at 10 knots.
Would like to accomplish the above with less than 600 lbs LA batteries.

I understand the tradeoffs among battery chemistries, motor, and controller types.
What I want help with is hull design. The trade offs between length to beam ratio, drafts, and hull geometry. I have purchased plans for 20 to 30 foot canoes and Atkin's Sergeant Faunce utility. By increasing the freeboard and decking the canoes, I think I can handle the open water, but my real issue is how much must I increase the L/B ratio to overcome the 1.3xsq rt of waterline? I would rather not go as far as the guy in the Wye Island marathon who used a 50' rowing scull!

Any ideas or experience or can you refer me to some sites or literature. I have already scoured the web pretty thoroughly.