Peter Wiley wrote:
I can buy a 3HP outboard weighing 15 kg and that runs for an hour on a
tank of 100:1 premix costing a few bucks and capable of being refuelled
in a couple minutes from a bigger can. Call it a kilogram of fuel per
running hour, it's probably less. The outboard costs less than $1000
AUD. Design an electric o/board with similar weight, endurance, power,
fuel weight and refuelling ability at a price point no more than 20%
more expensive and I'd buy one. Until then, forget it.


If you drop the requirement for similar weight... or seperate the weight
of the drive unit (since it's more than just a motor) from the battery,
then you can easily satisfy all those... and much cheaper, with greater
reliability and far lower operating cost.

Not to mention that it's quieter & can be much cleaner.


Point is, I can load an awful lotta fuel aboard before I get to the
weight of a big battery.

True. But you might be surprised at how little a battery you need, and
you can stow the battery anywhere in the boat. This minimizes the
problem of weight... even improves the ballast ratio, if it's well fixed
like it should be.


...As I burn the fuel, the weight diminishes.

Yeah, but on the scale you're talking about, by how much? A significant
fraction of overall displacement? I think not ;)
For ships, yes definitely, and this is an important factor in
calculating operating range.

Some years ago I had some friends that went gigging frogs regularly.
They used an aluminum johnboat and a trolling motor, a small electric
outboard. I was surprised at how fast & how far that motor & battery
would drive the boat... we went 3 ~ 4 miles out & back and the battery
was good for a couple of hours... and it was a junky old car battery
charged up by an automotive type charger. You could do much much better
today, for not a lot of money. BTW I always brought paddles just in
case, but we could never have paddled that boat as far, as fast.

Fresh BReezes- Doug King

Yeah, that was a boat that weighed 100 lbs, had flat bottom, flat sea state.
I guess I don't see how it relates to driving a sailboat through the waves
as you are coming in through the breakwalls during a blow.

Lonny B

--
"Rock stars! Is there anything they don't know?" Homer Simpson


"DSK" wrote in message
. ..
Peter Wiley wrote:
I can buy a 3HP outboard weighing 15 kg and that runs for an hour on a
tank of 100:1 premix costing a few bucks and capable of being refuelled
in a couple minutes from a bigger can. Call it a kilogram of fuel per
running hour, it's probably less. The outboard costs less than $1000
AUD. Design an electric o/board with similar weight, endurance, power,
fuel weight and refuelling ability at a price point no more than 20%
more expensive and I'd buy one. Until then, forget it.


If you drop the requirement for similar weight... or seperate the weight
of the drive unit (since it's more than just a motor) from the battery,
then you can easily satisfy all those... and much cheaper, with greater
reliability and far lower operating cost.

Not to mention that it's quieter & can be much cleaner.


Point is, I can load an awful lotta fuel aboard before I get to the
weight of a big battery.

True. But you might be surprised at how little a battery you need, and you
can stow the battery anywhere in the boat. This minimizes the problem of
weight... even improves the ballast ratio, if it's well fixed like it
should be.


...As I burn the fuel, the weight diminishes.

Yeah, but on the scale you're talking about, by how much? A significant
fraction of overall displacement? I think not ;)
For ships, yes definitely, and this is an important factor in calculating
operating range.

Some years ago I had some friends that went gigging frogs regularly. They
used an aluminum johnboat and a trolling motor, a small electric outboard.
I was surprised at how fast & how far that motor & battery would drive the
boat... we went 3 ~ 4 miles out & back and the battery was good for a
couple of hours... and it was a junky old car battery charged up by an
automotive type charger. You could do much much better today, for not a
lot of money. BTW I always brought paddles just in case, but we could
never have paddled that boat as far, as fast.

Fresh BReezes- Doug King

I'm really intrigued by electric engines and energy regeneration in general.
I'm about to put a 3kW system on the house, which should let me just about
break even over the year in energy costs. I think electic engines are the
future, but the cost and bat issues are still around. My current outboard is
a 4hp 2-stroke and weighs only 35 pounds. It works great, especially flat
out.

--
"j" ganz @@
www.sailnow.com

"DSK" wrote in message
. ..
Peter Wiley wrote:
I can buy a 3HP outboard weighing 15 kg and that runs for an hour on a
tank of 100:1 premix costing a few bucks and capable of being refuelled
in a couple minutes from a bigger can. Call it a kilogram of fuel per
running hour, it's probably less. The outboard costs less than $1000
AUD. Design an electric o/board with similar weight, endurance, power,
fuel weight and refuelling ability at a price point no more than 20%
more expensive and I'd buy one. Until then, forget it.


If you drop the requirement for similar weight... or seperate the weight
of the drive unit (since it's more than just a motor) from the battery,
then you can easily satisfy all those... and much cheaper, with greater
reliability and far lower operating cost.

Not to mention that it's quieter & can be much cleaner.


Point is, I can load an awful lotta fuel aboard before I get to the
weight of a big battery.

True. But you might be surprised at how little a battery you need, and you
can stow the battery anywhere in the boat. This minimizes the problem of
weight... even improves the ballast ratio, if it's well fixed like it
should be.


...As I burn the fuel, the weight diminishes.

Yeah, but on the scale you're talking about, by how much? A significant
fraction of overall displacement? I think not ;)
For ships, yes definitely, and this is an important factor in calculating
operating range.

Some years ago I had some friends that went gigging frogs regularly. They
used an aluminum johnboat and a trolling motor, a small electric outboard.
I was surprised at how fast & how far that motor & battery would drive the
boat... we went 3 ~ 4 miles out & back and the battery was good for a
couple of hours... and it was a junky old car battery charged up by an
automotive type charger. You could do much much better today, for not a
lot of money. BTW I always brought paddles just in case, but we could
never have paddled that boat as far, as fast.

Fresh BReezes- Doug King

On Fri, 8 Apr 2005 10:48:31 -0700, "JG" wrote
this crap:

I'm really intrigued by electric engines and energy regeneration in general.
I'm about to put a 3kW system on the house, which should let me just about
break even over the year in energy costs. I think electic engines are the
future, but the cost and bat issues are still around. My current outboard is
a 4hp 2-stroke and weighs only 35 pounds. It works great, especially flat
out.


Well, it's pushing a boat that weighs less than the motor.





This post is 100% free of steroids