Month: July 2021

Putting an electric outboard on my motor canoe is appealing for a few reasons. First, compared to a gas outboard, the electrics are quieter, and the ones with lithium batteries are lighter. They are more easily carried in that you don’t have to worry about spilled gas in the car and there are none of the cautions necessary with transporting 4-strokes in how you place them to prevent crankcase oil from flooding the engine. They can run at slower speeds for trolling. I tried a Minnkota motor on my Grumman canoe but sold it because of the battery weight – it was as heavy as my 6-hp Yamaha 4-stroke. I took a leap and bought a Torqeedo.

It has a lithium battery. It separates into 3 pieces for transport. It has a nominal 3-hp. It took some doing to get it installed on my canoe.

First, the tiller of the Torqeedo is centered on the motor, unlike a gas outboard with the tiller on the side. With the gas motor, you can center the motor and sit more or less on center and comfortably hold the tiller, which you cannot do with the electric. This setup ruled out putting the Torqeedo in the same position on the transom as the gas motor, so some kind of mount to one side was needed. The second peculiarity of the Torqeedo tiller is that is doesn’t functionally tilt up, like a gas motor. In use, it has to remain straight out, because if you tilt it up is comes out of its mounting bracket. It is designed this way to make the motor easy to disassemble for transport, but inconvenient for tilting – so, besides putting the motor to the side, you also have to be sure it can tilt since raising the motor when beaching or avoiding rocks is the order of the day with a motor canoe. Because of the battery weight on the back of the motor, it will naturally twist to one side as you tilt it, but you have to take some care in making this maneuver.

The second problem is getting the prop deep enough to avoid cavitation. News to me, Torqeedo’s 2 shaft lengths – ‘short’ and ‘long’ – are not exactly comparable to what we are used to in the gas motor world as short and long. The Torqeedo short is a good 2-1/2″ longer from top of transom to centerline of prop than the Yamaha. It was not immediately apparent why this was, so I made my first bracket for the Torqeedo to match the prop centerline height of the Yamaha. I made a white oak mount through-bolted to the port side of the transom, 2-1/2″ taller than the transom, so the centerline of the Torqeedo prop was as the same height as the Yamaha –

I made sure the top of my add-on mount would not interfere with the tiller of the Yamaha. Two obvious differences are the prop sizes – the Yamaha is 7-1/4″ diameter while the Torqeedo is 10-1/4″, and the shaft length previously noted. Also, the underwater bulk of the Yamaha is significantly smaller than the Torqeedo, which includes the full motor, and further, the Yamaha has an anti-cavitation plate which the Torqeedo does not. When I took it out for a test drive I found that the prop cavitated at any speed above 5 MPH, and that was only using about one-third throttle. There seemed to be lots more power to the motor which wasn’t being put to use and certainly nothing equivalent to the Yamaha which was happy at full throttle and 14 MPH. On the plus side, it slid along at 2-3 MPH almost silently and would do that for probably 8 hours on a single charge, and could be fine adjusted to optimal trolling speed without the noise, vibration, trolling bucket etc. rig I use with the gas engine.

‘Research’ revealed that electric motors turn at slower speeds than gas, and need larger props to be efficient, and I hadn’t provided the minimum requirement of 1-1/2″ of water between the top of the prop and the bottom of the hull at the transom (this is not stated in the Torqeedo manual). I only had 3/4″. Ah-ha! That is why the shafts are longer on electrics. I had to lower my mount. There was only so much I could do while still retaining my transom corner braces, but I was able to lower the mount by 3/4″ by cutting out a recess for the motor brackets.

The motor can still tilt, albeit carefully, and I have 1-1/2″ between top of prop and bottom of hull, so things should be better. I will try it as soon as it stops raining.

I had the boat out for a few days fishing. The Torqeedo performed perfectly, using only 30% of its battery over 8 hours of speeds around 2 MPH. It still won’t push the boat above hull speed, and battery use increases significantly as speed goes up, but that is not what I want it for. I don’t hesitate taking it out for a whole day with just the Torqeedo, knowing what I can get out of a single charge. One thing I did find out is that the plastic pin securing the battery will sink if dropped overboard – nice that it is bright orange.

My belt sander, which I bought new in 2001, is one of the most-used tools in my shop. In 20 years I’ve only replaced the drive belt and the capacitor once, each. Last week however it slowed down while running, came to a stop and refused to start. When I hit the ON switch, the motor would turn a fraction of a revolution, make a buzzing sound but not come up to speed – no starting torque. It has a start capacitor which seemed like a fair place to start, but after replacing it with a new one, there was no change. I had to learn something about the motor.

(Always assume that a capacitor is charged with potentially lethal voltage. The two-pole variety like the one used for this motor can be discharged by shorting the poles to each other with an insulated handle tool.)

The motor – how to get it out. Removal of the bottom cover plates is straight forward. The motor is hung on a press-fit rod that runs from the front to the back of the casing, making the belt self-tensioning from the motor weight. There are 2 C-clips on the rod that have to be removed to drive the rod out. It is best to drive the rod from back-to-front (switch side) to get it out. This is not apparent from parts diagrams which show the rod coming out the back – to my misfortune since that is how I drove the rod out on my first try, slightly damaging the casing in the process. Obviously, supporting the casing by backing up the part that you are banging on is a good idea. Once the motor was out, I could test it on the bench.

Besides the capacitor, there is only one other part in the electrical circuit that could be failing besides the motor, and this is a relay in the switch box where the capacitor is. With capacitor start motors, the capacitor supplies additional current at start-up, which must be cut back during run. Sometimes the cut back is accomplished with a mechanical / centrifugal switch in the motor. Sometimes it is done with a ‘potential relay’ that energizes two circuits, then cuts one off as the motor comes up to speed. The potential relay is the method used in this Delta motor. I was able to take the relay apart, look at the contacts, verify that nothing was sticking, and I was also able to rule out the relay by bypassing it and attempting to run the motor directly on the ‘run’ circuit with a pull-cord start. It behaved the same with the relay bypassed as with the relay in line – that is, it had no starting torque, if it turned at all.

In a DIY forum on the subject of capacitors I found a posting that was helpful. First, it said that in a situation such as this motor with an AC capacitor with just two lugs, there was no difference between poles in how they were wired, so I could not put the capacitor in backwards as I feared I might. Even more helpful to my situation was the information that a motor which turns freely without power but binds up when energized, as mine did, most likely had a problem with the rotor being off-center and hitting the inner wall of the stator. This appeared to be the problem.

The outside of the motor is 3 parts – the end caps which hold the shaft bearings, and the stator – which are held together with 3 long bolts. I found that getting these parts to line up exactly was the key. There is very little clearance between the rotor and the inside of the stator – probably in the range of 0.040″ – which makes precise assembly of the motor essential. The bearings are close to press fits in the end caps, and definitely press fit on the shaft. Heat used cautiously allowed me to get the bearings to seat in the end caps (there is a spring washer under the bearing on the off-pulley side) and I ended up using bar clamps to press the whole assembly together so there was correct alignment. I repeatedly tested the motor on the bench with different clamping positions until I found one where the motor both turned freely by hand, and started and ran smoothly. That is where I put the 3 bolts back through the casing and tightened them to within an inch of their lives. It has so far given 2 hours of runtime without failing.

Why it ran for 20 years and finally warped out of alignment I cannot say. I would probably not have gone through the hours it took to figure this out except for the fact that new machines are either very expensive, or very cheap, and used machines are hard to find. Our new-age era is one where repairing equipment is starting to make a lot more sense, now that we are in a supply problem with both new and old equipment.