Mys Terry wrote:
On 12 May 2006 07:17:02 -0700, "
wrote:


Mys Terry wrote:

On Thu, 11 May 2006 16:15:18 -0400, Wayne.B
wrote:


On 8 May 2006 21:23:55 -0700, "Zebra" wrote:


Can anyone tell me the thrust rating of the 1991 3hp Minn Kota trolling
motor? I bought the motor used, planning on using this motor as primary
power on my 10' Porta-Bote. Unfortunatly, there was no paperwork with
the motor.

There is a "rule of thumb" that estimates about 30 lbs of thrust per
hp. There are also the laws of physics that require about 750 watts
of power per hp. Since 750 watts equates to over 60 amps from a 12
volt battery, the likelihood of actually generating 3 hp from a
trolling motor is very remote.

The motor is not 3 horsepower. It is "3 HP rated". It was a marketing ploy to
address the age old question that so many people ask about the correlation of
thrust to HP. Minn Kota marketed this motor as producing the same thrust as a
typical 3 HP gasoline motor. Having done an A-B comparison against a 3.3 HP gas
motor, I can say it is more similar to an anemic 2 HP gas motor. It has further
disadvantages in that you have to carry not just the 25 pound Minn Kota, but a
fully charged 70 pound deep cycle battery for each couple of hours you wish to
use it.

Meanwhile, you can go faster and farther by substituting a 29 pound 3.5 HP gas
engine, and instantly replenishable fuel at 8 pounds per gallon. It will run
wide open for an hour on about 3 pounds of fuel.

Minn Kota does market an ACTUAL 5 HP electric for use on Pontoon boats, but it
has very limited range and needs a shorepower source to recharge it after each
use. I believe it is 48 volt?

Terry & Skipper, Clearlake Texas

I am interested in your ratio of equivalent-gas-motor-real-HP vs
electric-motor-rated-HP. Seem like the ratio is around 0.5 if a rated
3.3HP electric trolling motor is similar to a weak 2HP gas motor.

If a 24-volt electric trolling motor is rated as 80-lb thrust, the
rated HP will be like 2.67HP. When I apply the ratio that you have
come up with, the equivalent HP of a gas motor will be like 1.37HP. Is
this sound right?

I am asking this because I am thinking of getting a 24-volt 80-lb
thrust electric trolling motor or a small gas outboard for my 18-ft
boat. I want to use it in lakes that I cannot use my large outboard
motor, and also use it as backup power to limp back to shore in case
the main outboard is dead for some reason. I prefer electric because
it is quiet that won't scare the fish away. But I don't want to short
change myself either.

Thanks in advance for any info.

Jay Chan


I do not know the thrust of my "3 HP rated" Minn Kota. That
specification was never publicized by the manufacturer. All I know is
that it was no where near the thrust of a 3.3 HP gas engine that I
tested it against in a practical application. Not even close. This was
a "seat of the pants" comparison, with no scientific measurements
taken other than speed of the boat. This was on a 17 foot sailboat. I
determined that the electric was completely impractical for this use.
Even in very still water, it was markedly slower than the gas engine,
and in any current at all, or with a headwind, it quickly got worse.
I think it would be very impractical for you as well, given the
description of how you want to use it. Trolling motors really are just
for drifting around, to turn and position the boat. They are simply
not meant to drive the boat any significant distance.


Many fishermen use "trolling motors" to troll forward although not at
high speed. On my boat the 24 volt 65 lb minnkota will pull the boat at
up to maybe 3 mph as I recall. I wouldn't want to count on using it to
get home in bad conditions or if it was very far.

--
Del Cecchi
"This post is my own and doesn’t necessarily represent IBM’s positions,
strategies or opinions.”