On Dec 15, 2:50 am, Heikki wrote:
John C. wrote:
Run it as a generator and use it to charge an oversized bank of batteries.
With an electric motor you will gain variable speed and direction without
have an engineering nightmare.

I have been speculating about a diesel-electric propulsion for a smallish
sailboat. Does anyone have links to, or experience with, small electric
motors that are suitable for continuous use - most of my googling finds bow
thrusters and other extra machinery.

I am thinking of a fairly small engine, say 5-10 Hp, to be used mostly in
manouvering in and out of marinas, and occasionally coming home from a calm
sea. Would it make sense to mount the whole engine on the transom-hung
rudder? That way it could turn with the rudder, and give good steering in
both directions. When not in use, it could be lifted out of the water, so I
could use a decent size of propeller for it.

Would anyone care to shoot the idea down before I get too attached to it.
The whole project is on a dreaming level, I won't be building anything for
the next many years. But I still want to design it as if I was going to
build it some day soon...

Regards

Heikki
(Copenhagen, Denmark)

I would get a lower unit from an outboard and mount it permanently on
the bottom of the hull and then mount a 32V military surplus motor on
the inside and use the rudder for steering. Use three 12V batteries
in series for 36V which will drop to about 32V when under load. The
US Military made several large 32V motors that were used for fuel pump
in Jets and for power generation in the old prop planes. I have a 15
HP (Jet fuel pump) and a 25 HP (I think this came out of a B-25) that
I picked up at surplus prices a few years ago to make an electric car
which I later disassembled (yes it was successful). Am now thinking
about the 25HP for a small single seat hydroplane for short but fast
runs.