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)

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

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.

There are electric fishing motors, in the one horsepower or less
class. Maybe enough power for an under twenty foot boat. Not good on a
windy day.

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.

There is the tried and true outboard motor. Hanging stuff on the
rudder sounds like a poor approach to me. Not to mention ugly.

Would anyone care to shoot the idea down before I get too attached to it.

Shouldn't be too hard.

Casady

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

Look into golf cart motors. Consider duty cycle and run times with respect
to motor choice and battery bank size. Larger engines can be found in the
fork truck industry. Both the golf cart and fork truck would provide speed
and direction controls as well as basic mounting design. Your small diesel
generator may need to run much longer than your motor and or you will
require dockside recharging and use the diesel as back and top-off while at
sea. Keeping the generator output close to the energy needs of the motor
will increase the overall efficiency of the system. It would be useless to
require 4 hours of charging to produce the energy needed for 15 minutes of
motoring unless the battery bank was large enough to carry reserve energy in
far excess of your typical needs. The primary charge would then come from
dockside sources and your generator would be always on stand by.

There is a lot of info on the net about hybrid electric craft. You just need
to apply the information to your specific application.




"Richard Casady" wrote in message
...
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.

There are electric fishing motors, in the one horsepower or less
class. Maybe enough power for an under twenty foot boat. Not good on a
windy day.

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.

There is the tried and true outboard motor. Hanging stuff on the
rudder sounds like a poor approach to me. Not to mention ugly.

Would anyone care to shoot the idea down before I get too attached to it.

Shouldn't be too hard.

Casady

Gawlea!

Shore sounds like a job for two or even three trolling motors in
wells, two aft and one foreward.

Azipods!

Hanging propellors off the ends of the boat is a sure way to whip up
the air while props are out of the water in waves.

I would use the one foreward, mostly, for easy days marina docking,
etc. Should be able to steer it from the v berth in the sun or rain,
or remotely, or lock it and and raise it and plug the hole when ready
to sail. A fishguard bottom plate could be affixed beneath the prop
for maximum convenience and trouble free transformations. A one foot
lift might retract the prop and smooth the bottom. If located
foreward in the cockpit, it might sit next to the bridge deck step and
be innocuous raised or lowered.

With two after azipods, crabwise docking could become an exercise in
balance, pushing a keel sideways and providing some redundancy.

Using all three might permit all sorts.

No tranny saves weight for batteries. The generator you will need
anyway, if it is a little larger. Spatial accommodations could
benefit, if range might suffer, as if fuel economy were most important
on a sail boat.

With wind no motor is needed, if tradition tells anything. With no
wind, auxiliary drive is just that. 3/4 hull speed is very
economical. Sailing is an adventure, fun, not many of our livings nor
sustenance nor work, but joy and pleasure only. As with golf (I am
told) the longer time spent at it the better.

Now, if one azipod could charge batteries under sail, you might
subsist with solar cells...

The windage design of the topsides must accommodate low power
manouvering under power or in a breeze. A well balanced low drag
topsides plan should be utilized. A comparatively low elevation would
be best, as it is in any sailing vessel. I kind of like the idea of
raised deck and hull side portlights (a glass bottom?) as opposed to a
dog house.

Will you ever want for air conditioning? Possibly using one of the
wells, a stovepipe heat exchanger with only a small automotive heater
radiator underwater and ducted air tubes could provide basic survival
cooling. It would stow for sailing, being plugged in and deployed
overboard for overnight comfort at anchor. A sump dip tube for the
bottom of the stovepipe overboard would evacuate condensed humidity
scavenged from the recirculated cabin air. An air to air heat
exchanger would provide fresh ventilation. It won't make ice, but such
a system could defend your sweaty sanity and restlessness on a muggy
night with little weight or energy penalty, requiring only a small fan
for air circulation.

I can almost envision such an air conditioner in a bag, like a kayak.

As well, using an azipod well for a "stick in the mud" anchor, as used
on the junks of the Yangtze, might be an additional bonus.

Ain't it wonderful, the way one small decision regarding an auxiliary
powerplant can affect so many options?

Terry K

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.

On Sun, 16 Dec 2007 08:58:39 -0800 (PST), Terry K
wrote:

Shore sounds like a job for two or even three trolling motors in
wells, two aft and one foreward.

Azipods!

Hanging propellors off the ends of the boat is a sure way to whip up
the air while props are out of the water in waves.

I read your post with interest. As for waves, you only mount them, on
some kind of bracket, when you are going to use them. The original
reason for suggesting them is that they are compact, light, and cheap.
My reservations are mostly lack of power. One probably won't get it,
two stands a better chance, at least.

Casady