The lowest standard pitch for the Yamaha T 9.9 with 11.75 inch dia propeller is 7 inches.
Each 1000 motor rpm with a 2.92 gear ratio will yield a 0% slip speed of 2.27 mph. My extensive experience with this gas engine on a light skinny 28 foot Bolger Shearwater cat yawl was hull speed (6.5 mph) at just over half throttle, with great response in reverse as a bonus.
In my opinion it would make a great "electric" lower unit for electric power, if you can find one. Used as an electric auxiliary in a sail boat, the large blades and flat pitch will produce major amounts of drag under sail unless the tilting capability of the whole leg is utilized, ie. as a true electric outboard. The foot by itself would be perfect in a displacement powerboat under 25 feet.
Mike
--- In electricboats@yahoogroups.com, danbollinger <no_reply@...> wrote:
>
> They sound like a good fit. What's the pitch on the props for the 9.9Hp unit?
>
> --- In electricboats@yahoogroups.com, "bb386scn" <bb386@> wrote:
> >
> > Has anyone converted one of the Yamaha T series High Thrust / Dual Thrust outboards to electric? They come in sizes from 8 to 60 HP. They have been made since 1985 so used and relatively inexpensive ones are available.
> >
> > What drew me to this motor was the low gear ratio. The 9.9HP uses 13 and 38 tooth gears which gives a ratio of 2.92:1. It uses an 11-3/4" diameter prop which sounds like it would work well on a boat that is carrying a few hundred pounds of extra weight in the form of batteries.
> >
> > If anyone has converted one of these motors to electric, I would be very interested in hearing about the conversion and how the motor performed for you.
> >
> > Thanks!
> >
>
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