Motor and electronics for small boat

Hi foilers,

I have looked through the efoil part of these forums for getting good ideas for building an electric outboard for a small catamaran I’m building. The plan is to start with just a normal catamaran for 2-4 people and if everything works well i might add foils at a later stage.

I need help choosing motor and other electronics for this boat. My plan is to build a similar mast and motor setup that most efoilers use. But what motor though? My guess is that 10kw of peak power would be good. Since I’am building a catamaran perhaps using two smaller motors, one for each hull could be a good idea. What are your toughts?

I could provide more details if needed.


Please provide more details so you can get better advice.

The hull is built according to plans for a Tornado

The goal is to build something like this

As you can see it should be possible to use either one or two motors. I’m in the process of building the hulls and looking through the internet for used 18650 cells.

I hope this is enough information for some thoughts.

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I would choose 2 x 80100 outrunners. Are you going to use it in fresh water?

I will use this boat in Östersjön which has brackish water. This means there is some salt but not as much as usual sea water. But a very good point. How to protect the motors from corrosion?

Why that particular motor? And a outrunner for a specific reason?

A lot depends on budget…

If you want to go cheap with a bit more maintenance, then use 80100 outrunners.
If you want an easier to maintain solution, then go for D85 inrunners. They more expensive but are waterproof and serviceable.

What is a D85 inrunner? I can’t find any references to that on the forum. I’m more used to the naming convention xxyyy.


d85 - motor with diameter ~85mm, example from google - RTD85L130 motor

That not usual size for efoil

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Excellent thank you, i should have guessed D was short for diameter.

I think the 80100 outrunner suggestion sounds good with a budget in mind. The whole project is a proof of concept and upgrading the motors later if the project is successful could be smart.

So what escs are suitable to use with these motors? Are there any double escs that could handle the power?

If you put a motor on each hull you will need to use single esc’s as they need to be very close to the battery pack and you also do not want your motor phase wires too long either.

It is to be decided if I will put a motor on each hull or just use a central outboard style motor.

The main advantage of a central motor is that I could use a normal outboard for testing purposes. And as you say, the wires could allow for a double esc.

The advantage of one on each hull is that i could turn 0 radius turns by running each motor in oposite directions.

When talking about a 80100 are you guys implying a wet drive system where i have to seal the motor with epoxy?

Would 65161 inrunners be to small for this application?

Best is just buy motor and boatmount of the new waydoo_one efoil and you can use this motor for your boat…see

No, no one wants a waydoo that will burn…

I doubt this was real… looked at it several times… Did you ever have electronics burning? If so you would no this is really black smoke not just a flame…actually never saw big for flames for that long period on the shortcuts I produces myself… So yes maybe, but I highly doubt it`s real… Take into account there are a lot of competitors out there who wants to see that brand struggling… If I think of it could be an advantage for me too…they have some really nice parts I could use for my DIY :rofl:

The fires were very real and have happened to multiple users in the Facebook groups… It’s been extensively discussed in another thread so don’t sidetrack this thread. You can build a much better performing setup with better and cheaper DIY components than Waydoo offer, so Waydoo is pointless in the DIY realm!

I just saw this video and as I said I dont believe it as I know how fires of electronic looks like, you always have black smoke and not just a bit, really massive. In this video you see nothing of that and you dont see any damage… I don`t believe every bullshit if there is strange physics going on…but this is wrong thread tho and not my business;-)

For your other point, if I sum up all , my do it yourself parts (inclusive 1 burnt flipsky ESC, 2 inop MAytec Remote, 2 BLDC Motors, some CNC parts+board and 14s 35Ah bms battery) I end up with almost 3500+ so, not as cheap as I thought some months ago…and I don`t count the work building it.

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You clearly don’t! With high voltage and a proper short circuit there’s so much power it can flame up immediately.

Well with 55V and I think max 200A I doubt, and where is the typical electric black smoke… You are free to believe whatever you want…i had quite some electronics on fire here and my experience is totaly different…but as you said not the right topic here…

I have let the magic smoke out of many, many electronics over the years. I believe the waydoo fire videos are real.