T-Pain Is On A Boat: [Electric Boats] Re: motor overheating

Monday, June 22, 2009

[Electric Boats] Re: motor overheating

Colin,

Practically speaking (with prop diameter limitations), you are right about electric vs ICE horsepower. However, if you can afford giant propellers and reduction gears (or severely shallow pitch), six knots against a headwind vs six knots calm wind would just require different amperages, as the propeller/motor would be spinning at nearly the same rpm (voltage) in either case. You still get the efficiency of higher voltage, AND the emergency power reserve of over-amping the motor to your hearts content.

Mark Stafford

--- In electricboats@yahoogroups.com, Colin Girvan <colingirvan@...> wrote:
>
> Good point Dennis, I hadn't thought about actually losing power at cruising speed. So I guess when people quote the advantage of an electric motors ability to put out 2 or 3 times its rated horsepower for short periods that it's actually a bit of a fallacy as this is not really usable power.
>
> I appreciate your comment about trying to exceed hull speed, but my thoughts were not so much aimed at speed but more in the situation of fighting headwinds into an anchorage or channel. There have been several posts in the past (namely Arjan Bok and I think the other was Keith) that have given me pause.
>
> It seems that the general consensus that an ICE engine can be replaced with an electric motor one third the size might be good for calm conditions but in adverse situations it might be more like 1:2 ore less.
>
> Colin Girvan
>
> BC Canada
>