Hi John,
If full speed is only 3kts, then I agree, all motoring will be at full throttle. But an well engineered electric drive will deliver more speed with less energy than a trolling motor.
Using my Torqeedo 801 on my inflatable dinghy, I rarely use full throttle, half throttle seems to deliver about 3.5kts from 400W. On my 5 ton ketch, 500W gives me 3kts and 1000W drives the boat at 4kts. In practice, more than 90% of my motoring is at 1500-2500W or 4.3-5kts. That's still less than 1/2 power for my drive. I'm guessing that I could throw more energy into a trolling motor and take longer to get anywhere.
And efficiency is important, even for the smallest drive systems. Every wasted watt is a weight and cost penalty in batteries that you need to carry that don't increase your speed or range.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "John Zimmerlee" <john.zimmerlee@...> wrote:
>
> The cheaper Minnkotas do use a 5 speed forward, 3 speed reverse control
> which is wired through resisters mounted in the front of the motor. The more
> expensive ones use a pulse width modulation board with variable speeds. PWM
> switches the full 12 volts on an off rapidly. The more rapid, the faster you
> go.
>
>
>
> At slow speed, PWM, is more efficient, but for us guys, full speed is where
> we're at . . . most of the time. At full speed, the cheaper motor actually
> pulls less current than the more expensive one.
>
>
>
> All Minnkota trolling motors have a 4" pitch prop. No matter how big a
> motor, or even multiple motors on one boat, top speed is around 3 miles per
> hour. I can't imagine going anywhere at a lower speed.
>
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