12 volt trolling motor

[Nels]

What happens if one exceeds the 12 volts for a 12 volt trolling motor? Can this voltage be upped? without destroying the motor?

[Wayne Jeffers]

A 12-volt battery puts out about 12.7 volts when fully charged.

An alternator will typically charge a battery at up to ~14.4 volts.

A 12 volt DC motor can probably stand at least 15 volts without harm.

Too high (I'm not sure how high is too high) will burn it up.

What do you have in mind?

Wayne

[Nels]

I want more speed!!!

[Gary E]

Originally posted by Nels:
What happens if one exceeds the 12 volts for a 12 volt trolling motor? Can this voltage be upped? without destroying the motor?Can the voltage be increased?... well, yes it can, and your desire for more speed will be acomplished, but let me ask you for how long do you want the speed?

A true story should help here....
My wife and I were visiting a family that used to live near us in their new house in a faraway town at Thanksgiving. After the dinner and cleanup my wife said "I'll run the sweeper"... She plugged in the Hoover and wow did it do a good job, mattera fact it damn near sucked up the rug. It was then that the Dad in the family came rushing into the room and explained... Seems that the house had a window A/C unit for the summer, but the youngster in the family did not install the special 220v outlet so he put in a std 110v...THEY KNEW WICH one to use for the Hoover, but nobody else would of... Moral of the story is that you can run a lot more voltage into the motor and it will go a hellova alot faster, but for how long?.. nooobody knows...

[ 08-27-2005, 11:24 AM: Message edited by: Gary E ]

[Wayne Jeffers]

Originally posted by Nels:
I want more speed!!!Nels,

How big is your boat? Length? Weight?

How fast are you wanting to go?

12-volt trolling motors are rated by pounds thrust. Do you have a motor with enough pounds thrust for your boat?

If you can get a small electric motor to turn twice as fast without burning it up, the little propeller may simply cavitate and you'll actually go slower. :(

Tell us what your set up is right now.

Keep in mind that the best you can do with an electric motor is the hull speed of your boat.

Wayne

[Nels]

I have a 46 lb. thrust Motorguide motor, pushing a daysailer sailboat, approx 700 lbs. I can just manage 3 knots at full power. Can I get 4 knots by tweaking this or that?

[Gary E]

Originally posted by Nels:
I have a 46 lb. thrust Motorguide motor, pushing a daysailer sailboat, approx 700 lbs. I can just manage 3 knots at full power. Can I get 4 knots by tweaking this or that?Probably not, as what you want is 33% more speed which would probably require more than 50% more power. Even if you did up the voltage and current to the motor, how long do you expect it to last with that much additional demand.

I can not imagine that you could even tell the dif tween 3 and 4 kt... how do measure it anyway?

Your best bet is to get a much more powerfull motor if more speed is what you really want.

[Nels]

I measure my speed with a GPS. I want to be sure I can make it through a local inlet (against the tide) which I guess to run at least 2 knots. I'm just looking for some peace of mind. Anyone have experience with higher pitched props on these motors. A company called Kipawa sells a prop that may be of use to guys like me - higher pitch, more top-end speed.

[Wayne Jeffers]

Originally posted by Nels:
. . . Anyone have experience with higher pitched props on these motors. A company called Kipawa sells a prop that may be of use to guys like me - higher pitch, more top-end speed.No experience with higher pitched props, but I think this is a better bet, so long as you don't over-stress the motor.

How long is the boat at the waterline? It doesn't have a big ol' submersed transom dragging half the lake/bay behind it, does it?

At 700 pounds, I'm guessing that it is long enough that hull speed is at least 4 kts or more. If that is so, it won't take so much extra power to get to 4 kts. If your hull speed is 3 kts, you're just not going to get any more from an electric motor.

Wayne

[Gary E]

Originally posted by Nels:
I measure my speed with a GPS. I want to be sure I can make it through a local inlet (against the tide) which I guess to run at least 2 knots. I'm just looking for some peace of mind. Anyone have experience with higher pitched props on these motors. A company called Kipawa sells a prop that may be of use to guys like me - higher pitch, more top-end speed.The Sea Scouts that I belonged to as a kid had a Lightning wich was 19 ft and I am guessing about 700 lbs. But then add the 3 or 4 of us in it and it was easily doubled, and IF we wanted a motor on that I am sure at the minimum it would require 3 HP... and it sure would not be electric.

Now, back to your boat, wich I am only assuming is about like a Ligtning. You allready have this electric motor, so what does the manufacturer of the motor say about increasing the props pitch?

That Kipawa company that offers a higher pitch prop, what do they say? My guess is they say a lot of maybe this, maybe thats, but if they will sell you one with a 2 week money back return, give it a try. I am guessing that they wont, because it most likley will not help you, but hey, ask, all they can say is YES or NO.. and who knows, it might help.

If you do this, do you have a Amp and Volt meter to keep an eye on the power draw?

Bottom line here is you are trying to use a trolling motor for something it was never intended to do, and most likley will fall apart long before it's expected lifespan.

through a local inlet Hampton Roads? ..

[Nels]

You're close - Lynnhaven Inlet

[Frank Wentzel]

Nels

Some time ago someone on the Forum did thrust/speed calculations for my Egret(I wish I could remember who did it - I never did thank him.) Of course, the required thrust for your boat will be lower since it is a lighter boat. But, because your boat is shorter on the waterline, the curve will start to run wild at an even lower speed.

Here are the results of my benefactor's calculations.

Frank, is your Egret type sharpie a double ender? In an idle moment I drew a 28' double ended sharpie weighing 3500 lbs. At a given speed force required is - 1knot-5lbs, 2knt-9lbs, 3knt-22lbs, 4knt-48lbs, 5knt-88lbs, 6knt-158lbs, 7knt-264, 7.4knt-317lbs.

/// Frank ///

[ 08-29-2005, 09:24 AM: Message edited by: Frank Wentzel ]

[willmarsh3]

I just used a 55 lb thrust Minn-Kota trolling motor on my Elver yesterday. The boat weighs about 1300 lbs empty. I'm thinking 1700 with us (two adults) and cooler and such for the day's sail. The wind was blowing about 5-10 knots into the channel that we were coming out of. I had the sails brailed so there was some windage from that. At full thrust it pushed the boat along at I'd say 2 knots. It was sufficient for maneuvering around the marina but there are some quirks in the setup that I learned about. In particular the long skeg on the Elver makes turning in a tight radius more difficult than for a skiff.
Pls note that I intended this kicker only for maneuvering in and out of a marina or boat ramp and it did the job fine.
I hope this bit of information helps in your decision.
Will.

[PaulC]

One option for "insurance" would be Twins. Does a second motor fit in the budget?

[StevenBauer]

You need to find and read John Blazy's posts here about his homemade Kort Nozzle. It's a fairly simple modification and improved his performance alot. You might try searching on "glass bottomed boat"

Steven

[stevenj]

You're close - Lynnhaven Inlet neat, you live in my favorite fishing hole!! smile.gif I live up the Rivah from ya....

stevenj

[tidmarsh]

Originally posted by Nels:
Anyone have experience with higher pitched props on these motors. A company called Kipawa sells a prop that may be of use to guys like me - higher pitch, more top-end speed.I have one of their propellers on the trolling motor I use for my little sailboat. I don't have a GPS and haven't measured the speed yet, but it is noticeably faster with the Kipawa prop than with the stock Motorguide propeller.

They're cheap enough ($30) that I'd say try the propeller before boosting the votage and risking your trolling motor, which probably cost more than $30.

[Nels]

tidmarsh,
Can you tell me which Motorguide you have - how much thrust? And which Kipawa prop you installed? (I couldn't find a prop to fit a Motorguide on their website. Do you have to adapt / modify another prop size?) Thanks so much!

[tidmarsh]

I don't see it listed anymore. I think it was a 350 for a 3.5" hub. The motor I have is 30-something pounds thrust (37 maybe?), and I had to modify the propeller by cutting off a bit of the hub and chamfering the edges with a sanding disk.

You might try emailing them to ask if they have one that will fit.