hull mounted electric motor

[kldubois]

Anyone working on hull mounted trolling motor, 24 volt system in lieu of gas motor?
Joe in Key Largo

[KPL]

Joe,

I can't say I'm working on it, but I have thought alot about it!  Here's my idea as posted on the yahoo compac site:

Anyway, I'm thinking about making an electric "inboard' for my 1982 CP16.  What I'm proposing is to buy a 80lb thrust trolling motor and cut it in half.  In the lazerrette, I'll drill a hole in the bottom and epoxy in place an vertical aluminum tube with an I.D. the same as the O.D. of the motor shaft.  I'll support it on three sides with plywood gussets and fiberglass epoxied in place. I'll then insert the lower portion of the motor into the hole, leaving 3" clearance for the prop.  I'll fair the exposed portion of the shaft.  To hold the unit in place, I'll use a stainless pin through both the tube and the motor shaft.  It won't rotate, because we can steer with the rudder.  I'll disassemble the throttle portion and mount in the cockpit well with a homemade throttle handle.  I'll need to do a little wiring..



I'll place 2 group 24 or 27  batteries under the bridgedeck to keep the weight centered.



This is what I'm hoping to gain:



1)       Quiet power ... 2hour endurance at high power, longer at lower settings

2)       Potential for regeneration (I'm sure this will take some engineering, but it'd be neat if I could charge the batteries while I'm sailing.)

3)       Easily removable – pull the pin, disconnect the leads, and drop the motor out the bottom.  If I fill the shaft with epoxy, I might even be able to do it with the boat in the water (I'll get wet, but that's okay).  Otherwise, easy to mount/dismount when on the trailer



Disadvantages



1)       Hole in bottom of boat – if I seal it well, and the top of the tube is well above the waterline, I think it'll be okay.

2)       Drag while sailing – although there may be the potential to find a way to provide just enough power to have the prop spin negating the drag, but very low draw

3)       Short range ~ 8 miles at max speed, little more at slower speed – although I seldom use the motor for more then a few minutes.... I did buy a sailboat after all.





What do you think?  Suggestions?  Recommendations?  Or feel free to tell me I'm crazy and it can't be done (or isn't worth the effort)

[rchiare1]

I think it is a great idea! But I am willing to admit that I don't care for the idea of putting a hole in MY HULL.
That said, the real draw back that I see is the limitation of range. To me the speed is not as significant as distance, I just hate the idea of not being able to get back to shore because I'm out of juice and the wind is not cooperating. More batteries would seem to be the answer, and more batteries means more ballast, so the big question, to me is mounting them.
There is a company in Athens NY that has been making electric powered boats for a very long time. I recently visited the factory, and saw pictures of some of their distinguished customers; Henry Ford and thomas Edison to name but two.   The web site is:  http://www.elcoelectriclaunch.com/ 
They offer components and expertise to set up any size boat to 'cruise' all day. In our case this is overkill but I think you will find some valuable information.
Hope this helps and I would really like to hear about your progress.

Bob