Re: [Electric Boats] Keeping HP comparisons simple

 

You are right John if you want to go cheap and still have something that can get the boat underway you do not need a controller. It is well worth it though for what you can buy one for. You could have a bunch of switches to do the same thing. The older Cushmans went like this. Three contacts 12, 24 and 36v plus one for reverse. They burn out though because of the current going through them. If you had three switches to control the volts coming from the battery you could flip one for 12v two for 24v and the third one for get up and go 36v  On the other hand you could just look for a used controller out of an older golf cart. Use a high torque motor low RPM. Cushmans had some 36v 2200 rpm GE motors with pulleys. get an aftermarket throttle control $65.00 I think and the used stock controller and you could put the whole thing together for less than $500.00 if you looked around. Dan --- On Tue, 8/24/10, John Green <v_2jgree@operamail.com> wrote: From: John Green <v_2jgree@operamail.com> Subject: [Electric Boats] Keeping HP comparisons simple To: electricboats@yahoogroups.com Date: Tuesday, August 24, 2010, 4:16 PM   Regarding the debating re trolling motors...... AS a know-nothing guy, I would like to get down to some basics on this! Maybe these questions below can be answered, maybe no-one has ever bothered finding this stuff out. Maybe thrust is a better comparison measure? Once again, my goal is regarding an old 6500 pound sailboat with centreboard, and I am really cheap due to wife's budget restrictions and whining. And I have a belief that the ICE's fitted to sailboats are generally way too much overpowered - the extra power achieves a little more speed, but not in proportion to the first few HP. And, again, I have a theory that electric drives can be way cheaper by using multiple smaller cheaper motors, and maybe no controller, just contactors. I am not saying that this would be a good way for a commercial sold unit, or have the same convenience, just that it might be possible with compromises. And I know that some of you here will disagree...... I have read here or in the low cost voyaging Group that two minnkotas can power a 26 foot boat OK. (Whatever OK is!) Now, these are measured/sold/priced by thrust in pounds. What THRUST would I get from a 30 pounder if I added a large diameter straight bladed prop such as model aircraft prop? How many would I need to achieve hull speed of, I believe, 6 knots? Could I make gains by converting to inboard electric, and using a model airplane prop instead of the regular one on the regular shaft - my current engine is an old atomic 4 gas engine. In other words, does the model airplane prop advantage apply in inboard installations as well as outboard trolling motors? Thanks, John -- _______________________________________________ Surf the Web in a faster, safer and easier way: Download Opera 9 at http://www.opera.com

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