A Troll in a Canoe

Overpriced gel or AGM batteries with carrying handles. The auto club around here keep big ones in their tow trucks and service vans, just for the convenience of not having to fuss with 'red to red, black to block'. But the kind that can crank a car don't last long, and the kind that last long cost far more than you pay to just buy the battery on its own. OK for running a radio at a campsite, great as an emergency backup when you're driving around in the snow, but if you need serious amp-hours there are cheaper ways.

 

The Beta version of the electric paddle seemed to do an honest 1-1/2 hours at a medium speed which is quite enough for my purposes. Most trolling motors are too heavy and powerful for my needs. I like the look of it. We'll see how much it costs!

The Red Barn/Duckworks test was in an 8 ft LWL rowing tender which is similar to one of my boats and seemed to go reasonably well: I would expect to get a bit more speed and/or range from my home designed and built canoe which cruise very efficiently, better than any factory kayak I have ever tried.

The high-aspect ratio blade is probably more efficient that the weed-free blade style, although more vulnerable. The 24V motor should also improve efficiency because of lower loss in the wiring. It would be of particular interest to a paddling buddy who is building a canoe. He was wondering about putting in a small motor well through the rear deck but the prop size on the average troller would require quite a cavity: the thin EP blade can be aligned with the shaft and would likely drop down a much smaller hole.

Thanks for the heads-up.

 

I have a well in my 18' sailboat (Iain Oughtred Arctic Tern design) to fit a MK Endura 36 motor with a 2 blade APC prop - like the Electric Paddle uses. The well "box" is 4.5" x 14" and the hole in the bottom is 3.75" x 10.5". The motor body is 3.25" dia. The prop must be aligned vertically to get it through the hole.

The EP would fit through an even smaller hole but the motor head would stick up - convenient but maybe a little ugly. With the trolling motor everything is underwater so nothing shows. Motor stows in a space 13" high x 14" long; i.e. in the well with a bottom plug inserted to fair the hole and reduce drag for sailing.

 

I guess the hole has to clear the motor although I am surprised it is that large. In pictures of the Electric Paddle it seems to have the motor on top with a gearbox ahead of the prop, making it very slim so a smaller motor well can be used.

 

I'm building a 20' trimaran sailboat that will weigh 500 lbs. I've been thinking of using an electric motor for getting in and out of the inlet and in tight spots as the boat is 17' wide. I've also been thinking of cutting the shaft and mounting it on the stern of the hull, which only clears the water by several feet. The rest of the motor can fit in the hull. I'd like to make if it lift (bend) 90 degrees to clear the water when not in use, remotely if possible, by rod, cable, ram or ??. Has anybody explored this type of project before?

Here is a picture of the stern area the waterline comes to just the bottom of the hull. the rudders will be in AMA's (floats) so there will be nothing in the way of the motor. The only problem is that you can not get to the stern from the cockpit.

Thanks!

 

If you don't mind the negative cosmetic aspect of mounting the motor on the aka transom you could just incorporate something to accept the motor clamps. You could also cut the clamps off and bolt the motor to the transom for a slightly cleaner look. You'd still have the motor pointing out the back a couple of feet when sailing.

Since you can steer with the rudders you can lock the pivot so the motor points straight ahead.

Tilt could be via a rope and pullley arrangement, maybe with block and tackle leverage assist.

Have you thought of putting the motor in a well accessable to you while sailing? No aesthetic degradation, no tilting mechanism.

Be sure to get a PWM speed controlled motor.

 

electric paddle

Someone on another site found the cost of "e paddle" to be $1000. Nimh batteries that come with it are at least 2X heavier than Lithium and you must keep constantly plugged in as the charge drops down 3% in a day and maybe 2% per day after that. Also the gearbox may be noisy like the Torquedo. You should be able to rig up something better than that for less $.

Porta

 

I'm not well versed in E motors what is the PWM speed control? The well sounds good but since this is a racing machine the hole will disturb the flow of water over the hull.

I like the idea of mounting on the stern but it has to be very clean and can not be reached by the crew (on the outside - inside the hull not much room but room for mechanical) as the sail blocks will be in the way and this is a sit in hull. Also is the factor of the distance and slope of the hull. Station are 1 foot apart.

Denny I've seen your WebSite before very nice boat you make there!

 

PWM means Pulse Width Modulation.

With the regular rheostat control a variable resistor is placed in series with the motor; running at half voltage for example, the resistor with use the same amount of battery power as the motor but will generate no useful energy, so half the energy is wasted. Running at less than half voltage the motor gets less power than is lost in the resistor.

Replacing the resistor with a PWM controller, the motor is supplied with full voltage pulses. The pulse On-Off ratio is varied (modulated) to control motor power, and there is very little power lost in the controller.

Unless the motor is run mostly at full power, the PWM controller will provide considerably more range from the same battery.

 

Good summary, ancient. The PWM is much less wasteful, but tends to be more vulnerable to breakdown especially around salt water atmosphere that corrodes everything. So I use the best of both worlds, with a LOWER cost resistor type motor set on highest speed and an external PWM. That way you are not dead in the water if the PWM goes down, you bypass that and go to resistor control.

Porta

 

From the price and control technology being used, I assume the current crop of motors are mostly the permanent magnet brushed type. Greater efficiency could be achieved using an externally commutated servo type motor, but at the cost of greater complexity and additional wiring. The cost would be higher too as these require a built-in sensor, but the control losses are lower and the motor itself has less loss and therefore runs cooler, allowing a more powerful motor in a smaller package. I have no doubt we will see this, if they're not already out there in the top-end products. I would not recommend cutting the shaft down on that type, a practise which seems to be quite common.

 

Ancient, No incentive to change from PM motors when used as they are meant- short distance positioning by huge bass boats in weedy environment with room for lots of batteries. They are a huge profit item as is with components costing less than maybe $25 in huge quantities and a little more for labor- why change? They are lousy when used as an afterthought for e boat applications, but the only thing available. The market for high efficiency outrunner motors, efficient props, geared quietly for high efficiency and great performance on low weight is small and therefore very costly.

Porta

 

PM is permanent magnet brush type? Why is not cutting the shaft reccomended?

 

Another though is a little reversible servomotor to lift the dagger boards, which will be small and light approx 12" wide x 2" thick x 3 ' long foam and carbon any thought on that? If you want to check out my project www.themanshed.net

Thanks for your help and knowledge!

 

Any reason you settled on a tri? What is the advantage over the pontoon (Hobie cat) design?

Porta