We sold the 25ft boat but still have the 7 ft inflatable. We live in a
city apartment. The old 2 horse power gas engine works fine but we
cannot keep it in the car or apartment due to its gas fumes. We are
thinking about an electric motor for the dingy. Any suggestions or
ideas as to what we should look for?
as always, thanks for you comments

On Sun, 28 Jun 2009 06:53:33 -0700 (PDT), richard
wrote:

We sold the 25ft boat but still have the 7 ft inflatable. We live in a
city apartment. The old 2 horse power gas engine works fine but we
cannot keep it in the car or apartment due to its gas fumes. We are
thinking about an electric motor for the dingy. Any suggestions or
ideas as to what we should look for?
as always, thanks for you comments

BTDT - I don't recommend it at all. You will have a motor which weighs
as much or more than what you have now, PLUS one or more 60 pound
batteries that give you a one hour run time (at lower speed than your
present motor) before you have to lug them ashore and charge them for
12 hours.

Pay a few bucks to someone to store it in their garage or back room of
a gas station or something.

If you can't manage that, sell the RIB and buy either kayaks, or a
portabote, which rows very well, can also be sailed with an optional
kit, and folds flat for storage.

richard wrote in news:4b9f3735-f3b2-4653-
:

We sold the 25ft boat but still have the 7 ft inflatable. We live in a
city apartment. The old 2 horse power gas engine works fine but we
cannot keep it in the car or apartment due to its gas fumes. We are
thinking about an electric motor for the dingy. Any suggestions or
ideas as to what we should look for?
as always, thanks for you comments


Unfortunate equations:

Runtime (R) = Amphours (AH)/Thrust (T) squared

....so plan on the dingy being a DISPLACEMENT hull on battery power.

Also, unfortunately, AH = Battery Weight (W)/50
and
Dingy Freeboard change (delta F) = 1/W squared



A good idea is to go OUT on the little battery and come BACK on the big
battery....Fuel reserve.....


--
-----
Larry

This concludes today's trolling motor power lecture.....been there, done
that. Gas is MUCH MUCH lighter than lead-acid batteries and MUCH MUCH more
powerful....

Little trick my neighborhood thieves have never figured out.......
Anything left in a ragged-looking pasteboard box next to the trashcans
never gets stolen....Leave the gas cans in the box...storage problem
solved. Mark the gas cans - USED MOTOR OIL for extra security. Hell, even
the trash man won't touch it then, and neither will the boat thieves on any
dock.

On Sun, 28 Jun 2009 06:53:33 -0700 (PDT), richard
wrote:

We sold the 25ft boat but still have the 7 ft inflatable. We live in a
city apartment. The old 2 horse power gas engine works fine but we
cannot keep it in the car or apartment due to its gas fumes. We are
thinking about an electric motor for the dingy. Any suggestions or
ideas as to what we should look for?
as always, thanks for you comments

Most gas fumes from outboards come from left over gas in the carbretor
bowl. You may be able to manage that issue by either turning off the
gas or disconnecting the tank while the engine is still running, and
then letting it continue to run unill all of the residual gas is used
up. It's worth a try. Don't forget to close the tank vent.

On Sun, 28 Jun 2009 06:53:33 -0700, richard wrote:

We sold the 25ft boat but still have the 7 ft inflatable. We live in a
city apartment. The old 2 horse power gas engine works fine but we
cannot keep it in the car or apartment due to its gas fumes. We are
thinking about an electric motor for the dingy. Any suggestions or ideas
as to what we should look for?
as always, thanks for you comments

I've been using a small 1/4hp Minnkota motor to push our 8' soft-bottomed
Zodiac around for years. I use a small 12v motorcycle/skidoo battery
that gives two hours of putzing around time before it drains. Great for
just touring the marina, going for supplies...whatever. Ditch the gas
pig.

On Sun, 28 Jun 2009 17:04:34 +0000, Larry wrote:

Unfortunate equations:

Runtime (R) = Amphours (AH)/Thrust (T) squared

...so plan on the dingy being a DISPLACEMENT hull on battery power.

Also, unfortunately, AH = Battery Weight (W)/50


Larry, what are you thinking?

You're equation for a 19 lb thrust trolling motor and a small 23 AH
"utility" size batter gives a run time of 3.822 MINUTES.

That setup gives me about 3 hours running time. Admittedly 19 lbs
thrust is not enough for an inflatable. However I did have an 8 1/2 ft
inflatable with a 35 lb thrust trolling motor (might have been 30) and
type 24 battery. I got about 4 hours run time with that and it pushed
the inflatble about 4.5 kts according to the GPS. 4.9 Minutes run time
according to your equation.

I'm assuming your equation is Runtime in hours = Amphours / Thrust in
pounds squared?

So Richard, if you're not in a hurry, pick up a 30 to 40 lbs thrust
trolling motor (you don't have to run it full power) and a type 24
deep cycle batter. A type 27 will give longer run time, but the 24 is
fairly light.

Rick

Rick Morel wrote in
:

I'm assuming your equation is Runtime in hours = Amphours / Thrust in
pounds squared?


My equations only showed the futility of using battery powered electric
drives compared to an outboard motor, nothing more. They were never meant
to be mathematically correct.

I was trying to point out the obvious and discourage him from this electric
nonsense when what he really needs is an old single cylinder 2-stroke and a
2 gallon gascan.


--
-----
Larry

If a man goes way out into the woods all alone and says something,
is it still wrong, even though no woman hears him?

On Mon, 29 Jun 2009 00:34:08 +0000, Larry wrote:

My equations only showed the futility of using battery powered electric
drives compared to an outboard motor, nothing more. They were never meant
to be mathematically correct.

I was trying to point out the obvious and discourage him from this electric
nonsense when what he really needs is an old single cylinder 2-stroke and a
2 gallon gascan.

It's not futile nor nonsense. I've used electric for my dinghies since
1999 with success and happiness. Total weight is little or no more
than an old 2-stroke and extra gas.

I have no objection to an outboard, but remember he's in a situation
where he has no place to store it except in the home or car. A smelly
and very dangerous thing to do.

Rick

On Mon, 29 Jun 2009 04:07:42 -0500, Rick Morel
wrote:

On Mon, 29 Jun 2009 00:34:08 +0000, Larry wrote:

My equations only showed the futility of using battery powered electric
drives compared to an outboard motor, nothing more. They were never meant
to be mathematically correct.

I was trying to point out the obvious and discourage him from this electric
nonsense when what he really needs is an old single cylinder 2-stroke and a
2 gallon gascan.

It's not futile nor nonsense. I've used electric for my dinghies since
1999 with success and happiness. Total weight is little or no more
than an old 2-stroke and extra gas.

I have no objection to an outboard, but remember he's in a situation
where he has no place to store it except in the home or car. A smelly
and very dangerous thing to do.

Rick

Old 2-stroke (3.5 HP) = 30 pounds
2 gallons pre-mixed gas/oil = 16 pounds
Total weight = 46 pounds
runtime = With 2 gallons of fuel? Bwahahahahaha!
recharge time = 1 minute
Additional runtime available in minutes at any fuel dock

Group 24 Deep cycle battery = 45 pounds
SMALL electric trolling motor (.25 HP) = 20 pounds
Total weight = 65 pounds
runtime = Do the math. 35 MAX usable amp hours, motor draws 35 amps at
full speed.
recharge time = 12 hours. Battery must be brought to shore and
attached to a charger for 12 hours before it can be used again.

So, 46 pounds gets you 3.5 HP for effectively unlimited runtime, and
65 pounds gets you .25 HP for 2 or 3 hours of runtime at MUCH slower
speeds before you need to go ashore for 12 hours.