In article ,
says...
SNIP some good arguments
True but the battery does offer some advantages. It's quiet
and you can place the weight of it anywhere in the boat you
want.

Think of that 50-pound trolling battery as a gas tank that holds (the
equivalent energy of) a pint of fuel, takes all day to "fill" (recharge),
costs $$$, and wears out in a few years.

That seems rather pessimistic. A plain old lead-acid battery
can easily run thousands of charge-discharge cycles if it's
treated properly. And the power equivalent is much more than
a pint of gasoline, especially if you factor in the woeful
inefficiency of internal combustion engines.

If you discharge your lead-acid battery to the 50% or 80% level,
you are unlikely to get thousands of cycles. 400 to 500 might
be a better upper limit.

As for power equivalent: a 100AH,12V battery at a reasonable discharge
level is equivalent to about 1.3HP for one hour. My own experience
with a battery of about that size and a trolling motor is that
you can propel a very light boat for about two hours at perhaps
1-3 knots on one battery. I think I would get about the same speed
with my 4HP Johnson OB at a fast idle. Whether that would take more
than a pint of fuel is a good question.


A big difference between charging a battery and driving an OB
is that the pollution from the motor goes directly into the
water. That can be a problem on some lakes.

http://www.windsun.com/Batteries/Battery_FAQ.htm

Fresh Breezes- Doug King


Mark Borgerson

On Thu, 13 Apr 2006 23:09:15 -0700, Mark Borgerson wrote:

As for power equivalent: a 100AH,12V battery at a reasonable discharge
level is equivalent to about 1.3HP for one hour.

That's a pretty big, heavy battery, not easy to carry around!

My own experience
with a battery of about that size and a trolling motor is that you can
propel a very light boat for about two hours at perhaps 1-3 knots on one
battery.

That's probably about right. How long does it take to charge though? And
how do you charge it? It's one thing if you have shore power or a
heavy duty alternator or genset aboard your yacht, but...

I think I would get about the same speed with my 4HP Johnson OB at a
fast idle. Whether that would take more than a pint of fuel is a good
question.

You don't need that much power. A .5 HP electric motor is probably good
enough. A small dinghy has a really low hull speed anyway, so running
your gas outboard at full throttle isn't much faster than at 1/3 or 1/4.
This translates to a smaller electric motor. IME a pint of fuel an hour
seems about right.

A big difference between charging a battery and driving an OB is that
the pollution from the motor goes directly into the water. That can be
a problem on some lakes.

This is true. In fact electric is all that's allowed on some lakes.

http://www.windsun.com/Batteries/Battery_FAQ.htm

I haven't read this page, but be careful about battery websites. They
contain more old wives' tales, mechanics' folklore, myth, and marketing
drivel than just about anything else.

I'm actually intrigued by small electric outboards. I'd like to have a
self-contained unit with a built-in Li-ion or NiMH battery. It could
weigh no more than a small gas outboard, run for two hours, and charge in
15 minutes off the generator in the "mother ship." Even if it were
very expensive, the quiet and cleanliness would appeal to a lot of people.

Matt O.

In article ,
says...
On Thu, 13 Apr 2006 23:09:15 -0700, Mark Borgerson wrote:

As for power equivalent: a 100AH,12V battery at a reasonable discharge
level is equivalent to about 1.3HP for one hour.

That's a pretty big, heavy battery, not easy to carry around!

My own experience
with a battery of about that size and a trolling motor is that you can
propel a very light boat for about two hours at perhaps 1-3 knots on one
battery.

That's probably about right. How long does it take to charge though? And
how do you charge it? It's one thing if you have shore power or a
heavy duty alternator or genset aboard your yacht, but...

I think I would get about the same speed with my 4HP Johnson OB at a
fast idle. Whether that would take more than a pint of fuel is a good
question.

You don't need that much power. A .5 HP electric motor is probably good
enough. A small dinghy has a really low hull speed anyway, so running
your gas outboard at full throttle isn't much faster than at 1/3 or 1/4.
This translates to a smaller electric motor. IME a pint of fuel an hour
seems about right.

A big difference between charging a battery and driving an OB is that
the pollution from the motor goes directly into the water. That can be
a problem on some lakes.

This is true. In fact electric is all that's allowed on some lakes.

http://www.windsun.com/Batteries/Battery_FAQ.htm

I haven't read this page, but be careful about battery websites. They
contain more old wives' tales, mechanics' folklore, myth, and marketing
drivel than just about anything else.

I'm actually intrigued by small electric outboards. I'd like to have a
self-contained unit with a built-in Li-ion or NiMH battery. It could
weigh no more than a small gas outboard, run for two hours, and charge in
15 minutes off the generator in the "mother ship." Even if it were
very expensive, the quiet and cleanliness would appeal to a lot of people.


As a device to get you from your anchored yacht to the shore, this might
be an attractive alternative. In most NW anchorages, you are seldom
more than a few hundred yards from the beach, so rowing isn't a big
problem---unless you have to cope with a few kids and a dog and an
inflatable that rows with all the directional stability of a soup
bowl! At times like that, a 1/2hp OB with an hour's endurance
might be useful.

With resonable efficiency 1/2Hp for one hour would need
about 1200Watt hours to recharge. That's about 100 Amp
hours at 12V---or about 4 hours at 25 Amps. Not an unreasonable
load for a husky alternator on a diesel trawler running 4 to 5 hours
between anchorages. (Friday night--11:30PM, good wine with dinner---
check my math!)

Mark Borgerson

On 12 Apr 2006 20:08:25 -0700, wrote:

This
creates a problem---how do I recharge the battery/batteries if I decide
to go with electric motor? Is it possible to do it through the running
car in some way? Is this a realistic approach anyway? Solar
power(likely, unrealistic)/other alternatives?

Electric power is not going to work for you unless you buy a generator
and a high capacity charger. If you're looking for quiet operation
you will probably be better off just getting a small 4 cycle Honda
outboard. At idle you can hardly hear them.

Recharge times will be too long on solar power or with your vehicle
alternator.

When you move to the wilderness, and disconnect from the artificial
urban environment, you come face-to-face with the key issue: Electric
vehicles require electric generators... somewhere. When you can just
plug your charger into the wall, that nasty generating plant is out of
sight and out of mind. But when YOU have to supply the electricity, you
end up with the same conclusion: burn fossil fuel.

But if you are going to burn fossil fuel, next you need to ask yourself
if burning the fuel in an engine in the generator is an improvement over
burning the fuel in an engine and using the power output directly, thus
eliminating the need to carry (and indirectly, to manufacture) the
battery and the electric motor, and eliminating the inefficiencies of
turning shaft horsepower into electircity, electricity into stored
chemical energy in the battery, stored chemical energy in the battery
into electricity again, and finally converting electricity back into
shaft horsepower.

TAANSTAFL

bob

wrote:
Hi,

I want to put a motor on an 8' inflatable dinghy. A big question is
whether I should use a conventional gasoline/oil based motor or go with
electric. The situation is as follows: I plan to take the boat out to a
complete wilderness (in a car/SUV) and use it there for, say, a week to
explore lakes and streams. There will be no AC outlets out there. This
creates a problem---how do I recharge the battery/batteries if I decide
to go with electric motor? Is it possible to do it through the running
car in some way? Is this a realistic approach anyway? Solar
power(likely, unrealistic)/other alternatives? I would not have asked
unless electric motor was not so nicely quiet and environmentally
friendly and thus appeal to me. Using electric motor has its value, but
it is not clear if it holds it in the above set up.

Thanks

8' ... have you ever heard of ... oars?

On Wed, 12 Apr 2006 20:08:25 -0700, dmitri.maslov wrote:

Hi,

I want to put a motor on an 8' inflatable dinghy. A big question is
whether I should use a conventional gasoline/oil based motor or go with
electric. The situation is as follows: I plan to take the boat out to a
complete wilderness (in a car/SUV) and use it there for, say, a week to
explore lakes and streams. There will be no AC outlets out there. This
creates a problem---how do I recharge the battery/batteries if I decide
to go with electric motor? Is it possible to do it through the running
car in some way? Is this a realistic approach anyway? Solar
power(likely, unrealistic)/other alternatives? I would not have asked
unless electric motor was not so nicely quiet and environmentally
friendly and thus appeal to me. Using electric motor has its value, but
it is not clear if it holds it in the above set up.

Batteries for trolling motors are heavy and take a long time to
charge. Even if you had a portable generator or oversized alternator on
your car, you'd have to run it for quite awhile. There goes your peace
and quiet.

As others have mentioned, a canoe or kayak with paddles might be the
ultimate solution. Or a small rowboat. Inflatable dinghies don't row
well enough for anything but short distances.

We've been very happy with the 2hp Honda BF2D we use for our dinghy. It's
completely self contained, with no external tank, and weighs only 28lb. It
runs well over an hour on a quart of fuel. It's dead reliable, and not
too loud. I recommend it.

Don't get me wrong, I love electric motors.

Matt O.

oh oh oh. gotta an idea!

Yellow "bannana boats." The are inflatable kayaks.
Very light
Very portable.. just roll them up
reasonably fast
much cheeper than all the other stuff.
Besides trying to compute BTU to KW to BHP, SHP, Jules, moles, etc can
be rather confusing for someone llike myself who still has 1200
flashing on my VCR.
Bob

On Wed, 12 Apr 2006 20:08:25 -0700, dmitri.maslov wrote:

Hi,

I want to put a motor on an 8' inflatable dinghy. A big question is
whether I should use a conventional gasoline/oil based motor or go with
electric.


I'm surprised at all the negative responses to this. My "other" hobby
(apart from sailing) is flyfishing, and at least here in BC, electric
motors are de regeur (ok, my French isn't that good - I SAID I was from
BC! ). In fact, a lot of lakes do not ALLOW gas engines.

A decent electric motor/battery will push you at hull speed for around 2
hrs, or trolling speed for at least a day. Hell, mine will push my 9.5ft
inflatable over 5 knots for 1.5hrs.

Charging IS an issue: Even a fairly decent panel (60-80W) will take a day
(more or less) to charge a Group 24 battery. But why not get a decent AC
charger like a Statpower and run it off a small Honda genset? (The DC
output off those gensets is WAY too wimpy!) That way, you're not polluting
the lake, you're getting the super-quiet Electric Experience, and an hr or
so running at dinnertime would set you up for the next day.

I'd say go with a Minn Kota Max40T and a deep-cycle Group 24 battery.

Lloyd Sumpter
http://www.bcboatnet.org

On Sun, 23 Jul 2006 21:36:53 -0700, Lloyd Sumpter
wrote:


Charging IS an issue: Even a fairly decent panel (60-80W) will take a day
(more or less) to charge a Group 24 battery. But why not get a decent AC
charger like a Statpower and run it off a small Honda genset? (The DC
output off those gensets is WAY too wimpy!) That way, you're not polluting
the lake, you're getting the super-quiet Electric Experience, and an hr or
so running at dinnertime would set you up for the next day.

I'd say go with a Minn Kota Max40T and a deep-cycle Group 24 battery.

Lloyd Sumpter
http://www.bcboatnet.org


Yes, small outboards spew pollution, stink, and are too damn loud.

Why can't they make an aircooled model with a real good muffler? I
hate polluting.