On Sat, 15 Dec 2007 09:50:00 +0100 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...

Regular outboards do have a fair weight/hp compared to e-motor and
batteries. The only thin you have to worry about is fuel. Or how did you
plan to fill your batteries?

--
Richard
e-mail: vervang/replace invalid door/with NL.net

Richard van den Berg wrote:

Regular outboards do have a fair weight/hp compared to e-motor and
batteries. The only thin you have to worry about is fuel. Or how did you
plan to fill your batteries?

Oh, I was planning to have a diesel engine (and a generator) running most of
the time to provide the electricity. The idea was to be able to place the
generator engine where I wanted it, and the propelller(s) and the driving
engine where they would be most useful. Instead of a solid shaft, I would
have flexible cables in between. I could run it on the batteries for a
minutes, if I needed extra manouvering, but in most cases, the power would
come from the generator. Also, I was hoping that the electric propulsion
would be smaller and lighter, so it would be easier to lift out of the
water when going by sail...

- Heikki

On Sun, 16 Dec 2007 04:35:35 +0100 Heikki
) wrote:
Richard van den Berg wrote:

Regular outboards do have a fair weight/hp compared to e-motor and
batteries. The only thin you have to worry about is fuel. Or how did you
plan to fill your batteries?

Oh, I was planning to have a diesel engine (and a generator) running most of
the time to provide the electricity. The idea was to be able to place the
generator engine where I wanted it, and the propelller(s) and the driving
engine where they would be most useful. Instead of a solid shaft, I would
have flexible cables in between. I could run it on the batteries for a
minutes, if I needed extra manouvering, but in most cases, the power would
come from the generator. Also, I was hoping that the electric propulsion
would be smaller and lighter, so it would be easier to lift out of the
water when going by sail...

For 1 kW (1,34 hp) you can count on about 10 kg motor weight for
standard 3 fase 2900 rpm motors. For a lighter motor you might use one
with a permanent magnet, no idea what it will cost.

--
Richard
e-mail: vervang/replace invalid door/with NL.net

Richard van den Berg wrote:
On Sun, 16 Dec 2007 04:35:35 +0100 Heikki
) wrote:
Richard van den Berg wrote:

Regular outboards do have a fair weight/hp compared to e-motor and
batteries. The only thin you have to worry about is fuel. Or how did you
plan to fill your batteries?

Oh, I was planning to have a diesel engine (and a generator) running most of
the time to provide the electricity. The idea was to be able to place the
generator engine where I wanted it, and the propelller(s) and the driving
engine where they would be most useful. Instead of a solid shaft, I would
have flexible cables in between. I could run it on the batteries for a
minutes, if I needed extra manouvering, but in most cases, the power would
come from the generator. Also, I was hoping that the electric propulsion
would be smaller and lighter, so it would be easier to lift out of the
water when going by sail...

For 1 kW (1,34 hp) you can count on about 10 kg motor weight for
standard 3 fase 2900 rpm motors. For a lighter motor you might use one
with a permanent magnet, no idea what it will cost.



Well, it certainly makes no sense to hook up a small diesel engine to a
prop shaft and prop. After all, it's never been tried before.

On Dec 16, 1:07 pm, HK wrote:
Richard van den Berg wrote:



On Sun, 16 Dec 2007 04:35:35 +0100 Heikki
) wrote:
Richard van den Berg wrote:

Regular outboards do have a fair weight/hp compared to e-motor and
batteries. The only thin you have to worry about is fuel. Or how did you
plan to fill your batteries?

Oh, I was planning to have a diesel engine (and a generator) running most of
the time to provide the electricity. The idea was to be able to place the
generator engine where I wanted it, and the propelller(s) and the driving
engine where they would be most useful. Instead of a solid shaft, I would
have flexible cables in between. I could run it on the batteries for a
minutes, if I needed extra manouvering, but in most cases, the power would
come from the generator. Also, I was hoping that the electric propulsion
would be smaller and lighter, so it would be easier to lift out of the
water when going by sail...

For 1 kW (1,34 hp) you can count on about 10 kg motor weight for
standard 3 fase 2900 rpm motors. For a lighter motor you might use one
with a permanent magnet, no idea what it will cost.

Well, it certainly makes no sense to hook up a small diesel engine to a
prop shaft and prop. After all, it's never been tried before.

West (Waste) Marine in their latest catalogue has a 6 hp electric
outboard, kinda expensive though. You could run a generator from a
small diesel like these Listers and have it charge a bank of batteries
that were your sailboat ballast and hav the batteries run your
electric outboard. Why carry around a couple thousand lbs of lead
ballast unless its going to do something like store electricity.