Rick, I'm curious how you are going to restore life in the old batteries. I've tried restorations by cleaning the internal plates and also with cadmium salts - both with varying degrees of success.

What is the rpm & torque or ratio? I watched some years a go as a human powered prop was developed for a high torque/low rpm bicycle/prop drive. It was quite different from a gasoline motor driven prop. Apparently there are standard naval engineering formulas for prop shape. We used several reference books.
good luck, Roger L.


--- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@...> wrote:
> Next step is to try to restore some life in the old batteries that
> have sat around for 7 years or so then do another test closer to >the 4kW motor rating or even into overload if the batteries can hold the voltage.
>
> Two thruster will not improve low end efficiency compared with a
> single unit but they will give heavy weather performance similar, or
> better than, the 60hp outboard. The tiny 14" prop on the outboard is
> cavitating quite heavily even at slow cruise around 6 knots. But
> worst situation is the ventilating that occurs in anything over 0.5m
> waves.
>
> Rick Willoughby
> rickwill@...
>