Use a grinder gearbox and torq-tube for a simple solution

There are plenty of videos of people using a weed eater as an outboard and the use a cheap harbor freight angle grinder 90deg head as a gearbox. a very nice set of 90 deg steel bevel cut gears. Why not top mount the motor using a torqtube down to the 90 deg gearbox to drive the prop. we could put the torquetube in the mast and design the gearbox as part of the mast so the prop basically would almost be flush with the back of the mast. this would be easy for the 3d printed/carbon wrapped design it would keep the motor out of the water and even alow outrunners, most grinders are 3~4:1 on gear ratio. the gear head and gears are smaller in dia then some of the motor cans we are already using and this is the way and outboard motor works. and befor anyone says grinders are 1000w vs our 3000w … take a look at some of the gear set ups being used even 3d printed. grinder gears are 100X stronger and are already being used in gocarts and boat drives. so bottom line we turn the mast into an outboard of sorts,lol thoughts?


1 Like

size is same dia lol… and pinion is already 8mm


1 Like

same thickness as it is now the torqtube would only need to be 10mm.

nice! , 10mm is ok to most mast (in the middle) , but the bearing? (spinning around 15000rpm on 500mm ) and the cutting to fit angle grinder on the mast ? at this point just make the mast?

the Torqutube is easy and an off the shelf part, we use them in RC helicopters pushing 6000w all day long @700mm. here is a vide from my field in Vegas to show the abuse you can put through it. Yes im proposing a whole new mast also the length would only be half as I think to put the prop still in the middle, not the bottom

CF torquetube

yes very impressive , i saw the video last year, are you sure you get 6000W on the rear propeller?

No, but more watts then the efoil needs thats for sure

I decided to mess around with this approach and I’m pretty happy with where I’ve gotten to. I added a chain reduction to bring the total reduction to 5:1. This is still in the proof of concept stage but I’m going to do some water tests off the back of my SUP once I get my amp meter.

Walmart Grinder
1.7:1 #35 Chain and sprocket

SSS 56104
Seaking 130A
Power hobby 6s 100c 6500mAH
Pacificmeister Prop

test video >