> For electric propulsion you will run the largest diameter that will fit.
There has to be a way to calculate an ideal prop diameter, doesn't there? I have a hard time believing that larger is *always* better. I haven't heard of anyone in a pleasure craft running around with >2' props, even though such things could be made to fit.
> Slip calculations have to take so many variables that yes, I just threw
> 12% out there.
Sure, I understand. Is 12% fairly reasonable?
> Since a electric will produce full rated torque at 1 rpm, a strong pitch
> will not stall the motor like it would an ICE.
I understand what you're trying to say here, but there is definitely a practical limit. Trying to produce 10kw of power at 1 rpm would be a huge current draw, which the batteries may not be capable of producing and which the controller / motor probably couldn't handle. I have read numerous accounts of people expecting their motors and controllers to be able to handle certain situations, but finding in reality they're overheating and either burning stuff out or the thermal cutoffs are tripping.
I think Eric suggested experimenting with ICE outboards first to help figure out the real requirements of my boat. That could obviously work, but I'd very much prefer to understand the theory better so that it was unnecessary.
I have the weight of my boat + dimensions. I have a good idea of what size battery pack and voltage. I will likely be using CALB cells, but I may be able to source some nicer CHL cells... either way we can figure out what power they're easily able to produce without damaging the cells (.3C continuous for CALB and supposedly 1C continuous for CHL, for ~6kw or ~20kw continuous available power respectively). I think we should be able to theorize about the best prop size given a particular motor+controller... but maybe I'm just wrong. I don't know what I don't know. :)
Thanks much for the responses so far!
-keith
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