Hello there everyone. Please bear with me. There is so much information here and its wonderful! I know that majority of this forum is for foils. But, I’d like to try my hand at a diy build for my kayak. I have been reading many post/topics on this forum and figured I’d start throwing out my ideas.
Current vessel of choice is a 2021 Old Town Sportsman PDL 120. Not the most agile kayak, but very stable. At the moment I am using a Bixpy J-2 to move the kayak. It works ok but I want more thrust. Max speeds that I get are just about 3.8 MPH on its own. About 4.5 MPH with me pedaling. Pros are that it is a paired motor and battery set. Cons are it is a proprietary motor and battery. It retails for about $1,300.
Spec sheets don’t say much about the motor. I assume it runs at 25.2V and 17.8 Amps? Based on the 450 Watts of the motor spec and 25.2 V of the battery.
The next step up would be a Newport Vessels NK180. It is just the motor alone and retails for about $1,000. Good thing is that you can pair it with a 24 V battery with as much Amp Hours as you can afford. In a way that’s also a con and increases the overall cost. So that paired with a battery can range from $1,500 to $2,000. It definitely propels the kayak faster than the previous Bixpy J-2. I know because my brother has it and I borrowed it once. I got an average of 1-2 MPH higher top speed.
Now for the barrage of questions. Is it worthwhile to even attempt a diy? I’ve looked around and still find myself lost in all of the information. I saw the Flipsky 65111 and figured it could work? I don’t have much experience getting this involved with ESC and motors. Could I run a compatible ESC without watercooling? I’d like to get closer to 8 MPH, essentially doubling my current top speed. The motor itself would be used sparingly to putt around 10-15 minutes on the water. And then 1-2 long stretches like say up to an hour to get across the lake. Would that be bad for the motor? Making it work too hard for too long? And last but not least I’d like the overall cost to be about the same as well, if not cheaper.
Just want to say thank you if you’ve read through all of this. I figured I’d try to present as much research and background info as much as I can.
If you are ok with building things then it’s not so hard to get a motor/esc combination to work. Biggest issue is a large enough battery, if you want 1hr full throttle with those motors and some tootling around then more than 2, likely 3kWh of energy would be needed. It’s a lot of weight so you would want to balance range goal vs weight.
Check out RCtestflight on youtube. He had made a few small electric boats/ kayaks/ paddle boards. Latest upload was a mini V8 powered SUP. Great channel as well.
You mention wanting to double your top speed as a design goal. I would suggest that the mounting position at the rear of the kayak might not be up to the task and possibly the “hull speed” of the kayak might not let you go that fast.
In other words if you mount a more powerful drive is the hull material in that area strong enough to handle the forces.
I would suggest you consider something like this as it is well documented here. You are not constrained by weight issues as in an efoil scenario.
I currently have a 12v 20Ah Lifepo4 Battery that I am using to power my fish finder, navigation lights, and go pro. Was looking at getting a 24v 50-100Ah Lifepo4 for this project. The 100Ah option looks like it’ll be right at 2.5kWh. Estimated to be 45 lbs, which shouldn’t be much of an issue. I can store the battery inside the hull of my kayak.
Do you think having an ESC inside of the kayak would be ok? Would it not get too hot?
Thanks for that. It reminds me of the Thailand boats with motors. Also browsed through his other videos and found he has a similar project. He used 2 65121 motors on a fiberglass boat but did not end up going over 1.5 m/s. The ESCs were getting into thermal regulation. I believe he was pulling 1500W out of each motor.
Current re-enforcement only consists of a offset mounting plate made from 1 inch (I think) King Starboard HDPE. Mounting location is not optimal as it is on the left corner of kayak as well. I’d like to keep the battery and ESC stored inside the hull. Will probably end up making something that will butt up against the rear of the kayak to help distribute the force of the motor as well.
