Electric motor to power a dinghy revisited
 

Electric motor to power a dinghy revisited
 

Did not mean to do this with the electric motor anyway. With the
electric, one would have to stick to the vehicle and make short trips
only, and it was initially proposed to be done this way. However, based
on the discussions, I got convinced that even that is not going to
work. Since electric does not seem to be an option anyway, why not try
to extend plans?

Electric motor to power a dinghy revisited
 

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

Electric motor to power a dinghy revisited
 

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

Electric motor to power a dinghy revisited
 

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.

Electric motor to power a dinghy revisited
 

Lloyd Sumpter wrote in
:

run it off a small Honda genset? (The DC
output off those gensets is WAY too wimpy!)

My Honda EU3000i puts out 12 amps on its charging output jack. Of course,
that won't compare to plugging the big Vector autocharger into the AC plug
and getting 40 amps...(c;