Update after running my Perkasa, the prop is too small and too coarse and the rudder too small. This I expected.
She sits a bit high in the water but is very stable.
My conclusion is that I am going to fit three screws, as per Lews design, and two rudders.

Chris, mine are all brushed. I use individual ESCs on each of the outer motors. Attached is a schematic. This helps in docking and gradual turning at higher speeds.
Lew
Florida ⛱️, USA 🇺🇸

Are yours brushed motors though? Some folks have got 2 brushless motors to work from one ESC but usually there are problems and consensus is that you need an ESC for each motor.

Three motors and three ESC's? Two of my boats have multiple (one 3 and the other 4) motors. Both only use two ESC's, and those are the outer two. The center motor(s) are operated by servo activated switches for forward only.

In running forward I use the outer motors to accelerate then kick in the center motor(s). This works very well. Don't need 3 or 4 motors to back up.

Lew
Florida ⛱️, USA 🇺🇸

looks pretty good to me. Cheers Ian 👍

Some folks think building light is the way to go for performance but I like to build heavy as I think they are more stable, less affected by wind and ripples and handle better and hull forms like this are very buoyant so I don't think weight is much of an issue, especially if you go down the brushless route with their power output. With three motors and three ESCs it will start to get expensive though!

Chris

Edit: overlapped with Ed so I see weight isn't an issue anyway, quite the opposite!

Hi Roy, Thanks but this one was electric when I bought it all I have done is to rip out the old motor, speed controller, receiver and receiver battery holder. This has been replaced with a 35Mhz setup with BEC and brushless speed controll and LiPos.
This boat has GRP hull and superstructure, it is a bit light so more batteries or ballast.

I do not want to pour cold water on this but have you weighed the boat?
Some of the old boats built for i/c engines are very sturdy / heavy and will disappoint in performance.
Just my experience.
Roy