Canoe powered trailer/mobility device.

My canoe is pretty basic; a Coleman Scanoe with Minn Kota Endura C2 12v trolling motor, 100w solar panel mostly for shade, special foam seating and steering so I can operate from prone or recumbent position. I cannot sit upright longer than a couple minutes due to a spine injury.

It's getting too difficult to load/unload for roof carry, so I'm building a trailer. It occured to me that the canoe already has the seating, steering controls, power source, cargo capacity I need for getting around on land in many of the places I want to be. It just needs wheels, and the trailer has those.

That's right, I'm going to drive my canoe around on land and use the trailer (unhitched, but tethered to the truck or ground anchors) to launch the canoe at boat ramps and more unfriendly shores. The truck stays high and dry, providing 2 winch anchors by way of the safety chain attachment points.

Single sided hub motors with wheel studs were probably the right choice. But I already put together the axle, suspension, wheels and 25.5" diameter tires without such provisions and I already have some 3 CIM gearboxes and motor controllers from an old robotics project so I'm going to try to make that work at the existing 12 volts. Motors and gearboxes mounted above the wheels, where hopefully they stay dry.

The 12ish:1 gear boxes were chosen for quick acceleration of a 150lb robot on 6" wheels, so I plan to slow it down and torque it up for a 900 lb unit moving at a crawl with 3 parallel 2" pulleys per gearbox shaft driving 1/4" round urethane belting that sit in grooves in the rubber trailer tires. 2 of the pulleys on each side will drive the wheels, the remaining serves as a winch drum for that side's line attached to the ground anchor. The stretchy belts can be quickly put on/taken off to make the trailer towable. Because the wheels are driven at the tire surface, and the winch drum is the same diameter as the drive pulleys, line speed and ground speed should be in synch.

I wrote this up today because I am about to call up belt suppliers to see what belts are appropriately high tension, abrasion resistant, yet high friction enough to be driven on 2" pulleys with <180 degree wrap. I want this to be in the public domain, unpatentable by anyone that might hear the idea today.

I'm happy to hear any comments or criticisms. Be brutal. I'd rather know something won't work before I invest in it.

Once this works, next step is wireless remote control of truck and trailer from the boat in the water, to achieve parking and redeployment for loading. Driving the trailer is easy enough. FSD when Cybertruck is available takes care of parking. Electric jack handles coupler height. The coupler lock would need to be automated, or just leave it loose till hitting the highway.

slomobile said:

I wrote this up today because I am about to call up belt suppliers to see what belts are appropriately high tension, abrasion resistant, yet high friction enough to be driven on 2" pulleys with <180 degree wrap.

Click to expand...

I'd start by looking at 8mm pitch toothed belts and sprockets.

Toothed belts were my starting point for transmitting the necessary torque from the small drive pulley, but they will not stretch or tolerate rolling, making removal/replacement more difficult. If the round urethane belts fail(likely), they are very cheap to replace. Toothed belts not so much. Also, the tires already have 1/4" rain grooves saving the trouble of borrowing a tire groover.

I don't think stretchy belts are going to do what you want. Better plan on using a gang of them on each tire if you go that way.

What do you think the failure mode would be?

In their native habitat, singly, these belts turn 1.9" roller conveyors moving boxes up to 140lbs without slipping. I have slightly less wrap, but can tolerate some slippage. There are 2 belts per tire because each tire has 2 rain grooves. They are made from 7000psi ultimate tensile strength material. pi * 0,125in^2 = 0.049in sq 0.049in sq * 7000psi = 343lbs tensile strength per belt. Up to 686lbs per tire.

Worst case incline is 20%. 900lbs vehicle weight * 20% = 180 lbs total required to pull the whole unit up the hill.

Motor stall torque is 21.33 in-lb X 3 motors per side X 12 gear ratio / 2in drive pulley X 2 wheels = 767.88 lbs force total available.

I think its worth the experiment. If it fails, I already have 2" 5mm pitch HTD drive pulleys available, just would need 2 100in belts and a tire groover. I haven't calculated, but guessed the tire was too big and sticky to allow any slip on it. I worried what would happen at the road contact bottom of the tire with toothed belts. When the tire deforms, will they deform with it or cause some nasty stress concentrations.

Edit: corrected belt area calculation. pi*r^2, not pi*d^2. Big difference, but still worth trying.
2000-5M-09 HTD Belt (400 tooth) and https://www.vexrobotics.com/htdpulleys.html pulleys, just documenting in case round belts fail or I forget what size I need.