The circuit board you can see "not the LED one" is the twin sync system, there are hall effect sensors on both engines with two magnets mounted in the rim of both flywheels. Only one magnet is used per flywheel but I drilled and mounted two per flywheel to keep the dynamic balance correct, engines are also rubber mounted.The LED board is in fact a rev counter which displayed each engine RPM in quick succession.
Windows are 1.2mm ply covered with aluminum tape and the clear plastic sheet has been silconed in to give a water tight seal. If I was doing this again I would use Ali sheet and bolt through just as the real craft. That's is what I will do with a 54inch Huntsman 28 I am building.
Props are not counter rotating, marine silencers live under the engines and are homemade. Boat is very quiet but you have that wonderful sound of twin engines in sync and she looks just like the real thing when underway. The bad news is that I don't have any video footage as I don't own a video camera but will try and find one or some one with one the next time I run.
I also have a 1/8 scale Bluebird K7 with Wren 54 Gas Turbine under constrution, that will need good flat calm conditions unlike the Huntsman which does tend to chew the water up after 20Min's or so!!
Glad you like it.
Regards, Chris Wright