Thanks Alessandro. Conversely, thank you for your information on brushed motors which I know little about. I do have some in my RTR boats but obviously they came installed with them.

I did think about using them in my slower models; River Cruiser, Fisherman and Faun but decided to stick with my favoured brushless, particularly having tried one in the River Cruiser where slow speed and moving off were very good. Some might think I'm crazy using brushless in such slow models. I could have got advice on what brushed to use but part of my decision was wanting to see how brushless worked in slow craft as I'd read mixed reports on their slow speed performance - the answer is to use decent quality motors and ESCs. Fisherman will be the interesting one as it will be pretty heavy, has a blunt nosed displacement hull with a very small motor.

The total opposite to my planing models where I oversize the motors!

Hi Chris, this information, based on your knowledge and personal experience, is very useful to me, but I think it will be useful to others as well. Thanks for sharing.

Thanks Bob, that's very kind of you.

Duncan, as Bob has demonstrated, inrunner motors can be used in "slower" models 😀 but usually they are used in models where higher revs are required e.g. fast electrics/raceboats and those with water jets.

Outrunners offer more than enough performance for sports cruisers where you don't really need more than 10k. rpm on the water (12k. out) and the prop shaft can be the limiting factor whereas raceboats usually use flexible drives.

I usually recommend outrunners for heavier sports cruisers and speed boats as for a given motor diameter they offer more torque but in reality brushless motors are so powerful it doesn't really matter!

The rpm of brushless motors (sorry if you know this) is governed by the kV stated which equates to 1000 rpm per battery volt which can lead to some seriously high rpm with inrunners as they can have very high kV.

I was late to the party as regards model boats and use brushless motors in all my builds, even the very slow ones, as I just love their engineering. Most of mine are outrunners with the one exception being my future water-jet jet project where high revs are beneficial and so I'm using an inrunner. Also inrunners can be more effectively cooled by using a water-jacket as the outer casing doesn't spin.

First photo shows an outrunner in one of my Fairey sports cruisers and the second is an inrunner as used in my water-jet project fitted with a cooling jacket.

Chris

Nicely explained Alessandro - well done 👍

Bob.