Kayak Trolling Motor (early prototype)

thingiverse

I made a video about it if you are interested: https://youtu.be/YSabVPTIL6g This is still a very experimental and "work in progress" thing... That means it is far from perfect, however, if you still want to give it a shot and build one yourself, here are some ideas: The Motor needs to be a 3674 (mm) brushless motor with a KV of max. 2000, if the output shaft is 5mm in diameter, it can be necessary to drill out the pinion gear on a lathe. I also recommend to disassemble the motor and grease the bearings with waterproof marine grease. It could also be a good idea to coat the steel of the coils with some paint to prevent surface corrosion. However, this only works if the tolerances allow it and since it is only surface rust, from my experience it is not that big of a deal. The gearbox needs to be shorter than 45mm and also 36mm in diameter and should have a reduction of 3 or higher, depending on what prop, power output and battery voltage you want to use. If you want to use the motor for higher speeds, I recommend to use a water cooling jacket for 36mm motors. The main housing is designed with a ca. 40(-50)mm long cooling jacket in mind. This design is not fully waterproof! However, I made the gaps between components and the main housing as tight as possible, so that they can be filled up with marine grease, furthermore, I recommend using the same biodegradable waterproof grease for the gearbox. Since the housing is hollow when printed with infill, it might tend to swim. So I recommend to drill some small holes in the outer shell to use the infill space for ballast water... The shaft should be 10mm in diameter and ca. 80mm long and made from stainless material (brass or stainless steel). The prop should be a 220mm diameter 3 inch pitch or similar, fixed to the shaft with a radial pin (->boring aid) and an M8 or M10 nut. The output shaft of the gearbox should be fixed to the prop shaft via stainless flat bottom grup screws (M4 or bigger) (2 or more if the gearbox shaft is only 3mm in diameter) (->boring aid) or also with a radial pin if possible. The clamps that fix the motor assembly to a plate that is then somehow mounted to the boat are designed with a 6mm thick aluminum plate in mind. I also included the f3d and stp files if you want to change something, like if you want to use a wider motor for example, like a commonly used 56xy outrunner motor for electric skateboards. However, if you plan to use a motor with less than 400KV, a gearbos will be no longer necessary. Thats about it. If you have any ideas how to improve/alter the design for other people that want to build this, or any questions, feel free to post a comment under this thing. By the way, I dont want to ruin anyones fun, but it might be worth checking out your local laws on how much power a boat is allowed to have without the need to register/insure/getting a drivers license. But I think if you keep it below 1kW on average, it sould be no problem almost anywhere.