trolling motor on dinghy

[tweitz]

I have a small (Walker Bay 8) dinghy, where even a pretty light outboard concentrates too much weight aft and will tend to overload the dinghy when my wife and I, two large people, get aboard. I have been thinking of lightweight solutions other than my present one (oars) and was wondering if anyone has tried using a trolling motor. There are saltwater compatible motors of very light weight, and I don't mind being limited to 5 knots or so. I recognize there is weight in the battery, but i can put that where I want. Any experience with this approach would be informative, especially as far as endurance and ability to deal with water that is not perfectly smooth.

[Tayana42]

Tweitz, electric trolling motors can work well on a small dinghy. They have advantages and disadvantages. Light weight and quiet are obvious on the plus side. Also an electric motor might allow you to avoid carrying gasoline if you don’t need it for anything else aboard. The weight of the batteries is a disadvantage and lifting lead acid batteries from mothership to dinghy and back is not easy. Also you need a way to recharge the batteries if you will be out of your slip for more than a day.

I used a Minn Kota motor for several years on an inflatable air floor dinghy. I loved the silent if slow propulsion. At first I had a single lead acid battery that would last a few days of use going from boat to shore and a bit of puttering about before needing to be recharged. Then I bought a pair of golf cart batteries that would serve my needs for a week or so between charges. The Honda generator solved the recharging problem but now we had to carry gasoline for the generator. My wife made a macrame cargo net that we used to lift the batteries with a multipart tackle to and from the dinghy. It was bit of a nuisance but doable. We found that trying to drag the formerly lightweight dinghy with a lightweight motor and two 65 pound batteries up a steep beach between wave sets was no longer a lightweight activity.

After several years I bought a Tohatsu 3.5 outboard which is only a bit noisier and is in all ways a more practical solution.

[hugosalt]

I use a Minn Kota Riptide 40 lb. thrust 36" shaft, the white ones,
on my 9ft 6in air floor inflatable. Powered by a small 35ah
agm battery (actually have 2)
Have never ran out of power as if going exploring bring 2 batteries.
Motor weighs 18 lbs.
Will move 4 men and gear faster than rowing in smooth water.
Usually 1 or 2 people little faster about 5 plus knots or so.
Observations...
Need higher thrust.
Higher thrust usually longer shaft.
Seems variable speed motors use less juice.
Good for short runs, as beats rowing.
Battery will last longer at slow speeds.
Recharge on dedicated solar panel but for extended cruising need to recharge on house or genny.
Small 2 or 3 hp outboard, much faster, better if longer runs in chop.
Works for me, no gas on my 30 ft.

[tweitz]

Thanks for he quick responses. I would expect to use it mostly to tool around the harbor or for short distances from the big boat to shore; a battery duration of 90 minutes or so would seem to be enough. I can easily bring the battery to my house to charge between uses. Sounds promising.

[RickG]

There are people that get by with trolling motors in Boot Key Harbor. Those folks would pull the shaft up out of the water when it was not in use. It can be a bit of a challenge if the wind kicks up. We have a Tohatsu 3.5 on our 68lb ultralight dinghy that does well. We saw a lot of the smallest Hondas on Walker Bays.

Cheers, RickG

[Lepke]

I have a 10' Livingston. I originally used a 2hp 2 cycle outboard with all the usual problems. I switched to the smallest Minn Kota, Endura C2. After it was stolen I went to Newport Vessels NV-Series 55lb Thrust outboard ($200 on Amazon). The Minn Kota moved the boat at about 5 knots, the Newport at 8-9 knots.

I use the boat as a utility boat around my private dock so no idea on how long a battery lasts. I would guess several miles. Charging a battery is so much easier than dealing with 2 cycle fuel and all the carburetor problems. And traveling, an extra battery is easier to bring along than a gas can, and less explosive.

[CFS Klopas]

I can't imagine doing 5 kt with a 40 lb motor. My 8.5 ft slat floor with a 45 lb motor tops out at 3 kts (GPS verified).

I have a used 105 Ah LA battery that lasts 2.5 hours, though perhaps a deeper discharge than is healthy.

[basssears]

Ted,

Check out this thread I started a while ago:
http://www.cruisersforum.com/forums/...ne-216173.html
just to get some ideas of what's out there (quite a few products mentioned).

You're using the phrase "trolling motor" but you might want to clarify what you're looking for as more of an electric outboard / electric dinghy motor. These seem to be lighter than trolling motors (and have lighter, lithium batteries) and more designed to move a smaller boat a little faster than a bigger boat at a "trolling" speed.

Lots of options in that field too, like battery that attaches where an outboard powerhead would be (convenient, one piece design but heavier) or two piece design (two things to move around, but each one is lighter, you can leave the motor on the transom and take the battery with you to charge).

I really like the look of the EP Carry:
http://www.electricpaddle.com
... but have not had a chance to try it out.

[CFS Klopas]

OP is talking about a heavy battery not attached to the motor, he seems to be talking about trolling motors rather than electric outboards. The outboards cost 4x more for marginally better performance.

[tweitz]

CFS Klopas is right. My big considerations are weight and cost, and while the electric paddle looks very cool, and is very light, a small trolling motor that can handle salt water and a small deep cycle batter would be a quarter of the cost and not much weight. In addition, I can move the weight to low and amidships, which is better than hanging on the transom. The dinghy is usually outside my door, and if i can just pop the engine on and tool around the harbor a bit on a limited battery life, that's fine with me.

[Volkeno]

I have been using the Minn Kota trolling motor with a West Marine flat floor 8.5 dinghy since 2001. I use the smallest 40 foot pound motor and it pushes the dinghy at 2.5 knots. In perfectly calm water it can push my 8000 pound sailboat at 2 knots, but it takes awhile to get up to speed.
I have used the black motors which are for fresh water in salt water. The first one shorted out a few weeks after a storm when the dinghy flipped over and the top of the motor was in the water overnight. The second one still runs, but I have replaced it with a Lehr 2.5 propane outboard that runs on the little camping propane bottles which screw directly into the motor, or you can connect a hose to a larger refillable bottle. Propane is a lot louder than electric, but it is 75% cleaner than gasoline and propane never goes bad if you don't use it for a year.
I mostly used a group 24 deep cycle lead acid battery which was a little heavy. If I was going to keep using that trolling motor, I probably would look at a small lithium battery like a motorcycle size so I would get more power and less weight. But it would cost more and I would worry about someone stealing it.
I wanted to get something like the Torqueedo, but it was a lot more money than the trolling motor and the propane outboard.
Minn-Kota should really look at attaching a small lithium battery to a trolling motor, so it's a one piece unit like the small gas motors, or my propane, or the Torqueedo. Torqueedo also has a small solar panel that the motor can run from, or extend the range if you have a place on the dinghy where it could be in the sun. There are a lot of electric outboards coming on the market that are only being held back by the limitations of battery.

[JimsCAL]

The issue is the battery. Weight, recharging, range, etc. My old 2hp, 2 stroke is 22 lbs. A 12v deep cycle battery is going to be double that. And I doubt a single battery will give you 90 minutes of running except at very slow speed.

[CFS Klopas]

Like I said, 2.5 hours at WOT for me, which admittedly is still only 3 kts. A 2 stroke would certainly give better performance, though even used ones are double the cost of a new trolling motor, at least in the US.

[Lost Horizons]

I had a smallest Minn Kota motor on an inflatable about 25-30 years ago and generally was very pleased with it. It could cover about 15-18 miles on a single Group 24 battery. After approximately 500 miles of use the contact group burned out and I had to return in reverse gear, which was fun maneuvering in Newport Beach harbor. I then had a 36 volt Riptide motor powering a 21 foot sailboat about 12 years ago. Boat dry weight was 2200 pounds, say 3000 pounds loaded displacement. It would do 4-5 knots with no wind, and about 2 knots into a 20-25 knot wind.
Those were two extreme cases of trolling motors, from the cheapest ($100) to the most expensive one ($600). In each case I used AC Delco marine deep cycle batteries at about $100 each. It is very likely that my next inflatable will be also powered by a trolling motor, probably a 12 volt version for the sake of simplicity, but I am concerned with the tidal currents in the area where I am now. Certainly, currents was not an issue in Florida and Great Lakes.

EP Carry would be a good alternative to conventional trolling motor if or when they reduce the price by a factor of three or so. Same goes for another popular electric outboard that is priced out of touch with reality.

[basssears]

Originally Posted by tweitz

CFS Klopas is right. My big considerations are weight and cost, and while the electric paddle looks very cool, and is very light, a small trolling motor that can handle salt water and a small deep cycle batter would be a quarter of the cost and not much weight.

Since I'm in the same spot as you (same dinghy even), can you share which trolling setup you've been looking at that costs $400? Would be very interested in seeing that layout.


As far as batteries, if you stick with lead acid you could also go with two smaller batteries instead of one larger one, either take only one unless you need both or take both and just switch between them as needed.