@Toto44 maybe you can put a aluminium tube around your motor like I did, that helps a lot for cooling the motor I think.
I was actually asking Toto as it looks like his motor is sitting in the boats slipstream which might explain the heat.
No, it is not. Deep enough in the water. And I do not really think that this would change much.
I dont think that an extra layer of metal will increase the cooling. The motor is surrounded by water, thats the best you can get
1 Like
The prop should be running under the hull. At a certain speed you lose efficiency and cooling otherwise. All outboards (including electric) are designed to run below hull level.
@toto I am not quite sure about that. Aluminium got 400 times more thermal conductivity then water. You will increase the surface where water can do its cooling Job a lot.
Only if the Motorhousing and the sleeve have a press fit otherwise you loos a lot of cooling.
Plus the diameter increase increase drag a lot
Yes of course press fit is necessary. increasing drag is no problem and isn’t really a big thing, because main drag comes from the boat itself. if you get 9,3kw instead of 5,5kw. Its worth it I think. But it could also be a wrong setting why you getting heating problems.
Hi, how far did you get with this project?
Considering something similar
Stopped it because of family reasons. I tried it out on the water twice but never got to trying to fix it. And now I’m on my next project where I’ll split the battery pack in two with half the voltage and new bmss. Pretty sure it’s a voltage drop issue between the packs.
Otherwise worked. But overall it works for low power. The mount to the boat struggles since it’s just abs skinned with carbon fiber. It needs some stiffer material like metal. Or lots of carbon fiber so the 3D printed shape is more for shape and carbon carries the different loads. Over all a fun project and it worked well up to 5 knots.
But the 3D printed jet outboard design I’m in my final stages I think will work much better. See my YT channel. The reason is that there isn’t any long shaft and the jet just pushes the boat forward. So there are no bending and attachment issues like with an outboard.
As it often is, if I did it again I would just try something without the long outboard shaft. Like having a motor connected to the boat, something to stop air being pulled down to the propeller and then use a separate rudder. That’s way easier to design too. And also much easier to travel with. Outboards are terrible to travel with in the car. This would be more efficient than a jet that has pretty lousy efficiency vs a clean propp running in the water.
But you got to fail to learn and it was still a half success. It might actually work up to plane if it was the battery. I could test that later when I get my son’s jet boat done.
Cheers