Victor how can I see some pictures pls. Im in Port Alberni with 34 feet of boat to push for fishing purposes up to 2.5 knots . ty
Congratulations on the completed conversion Victor.
That performance sounds about right. The Mars 0709 is only rated to 125A continuous and 300A peak. Peak amps ratings are usually for less than 5 seconds so if you're running 150A, then you might be past the top of the motor's specs. 125A is also 6.0kW at 48V so this motor is really only designed to produce a maximum 8HP continuous at the shaft. Getting 5kts out of 8HP in a 9 ton vessel is pretty good, I don't know that you should expect any more. I am a little surprised that your boat will motor at 3kts on less an 1.3HP, but I guess that it could be possible in a true dead calm. I'm just trying to imagine a 2HP outboard strapped to the back of your boat for comparison...
You may find that a 6kW motor is a little underpowered for a 9 ton boat, especially in your area with real weather and strong currents. Many people recommend at least 1kW per ton of displacement. Since most boats your size are powered with 30+HP diesels, the alternative 2.5 to 1 conversion ratio also comes out to a 9kW (12HP) motor to replace a 30HP engine. However, as some on this board will be quick to point out, peope were sailing without auxilliary power for centuries, so you don't really need a motor anyway. You'll just need to plan carefully to make sure that you're not counting on the motor to get you out of a tight spot.
So you might see a minor improvement if you tweak your installation, but you're already right in the middle of what many people get from an electric conversion. It sounds like your drive is doing very well on your first try.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "vjmtymo" <vjmtymo@...> wrote:
>
> Well, finally finished building the boat and the electric drive.... With 20 amps in flat calm I seem to recall about 3 knots, and full out (150 amps) we're around 5. Motor's topping out at 150 amps so it needs more work.
> Boat is an 18,000 pound steel 36 footer, 10.5 foot beam, with twin keels.
> I'm now in Victoria BC with some great heavy winds out of the Juan De Fuca Strait to play with this winter. Hopefully I can tweak up the system and get it working more efficiently.
> So, thanks to anyone who provided advice and incentive, as well as the pessimism to keep me from being delusional.
>
> Victor
>
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