Need help to power my 65" long "Klondike"

[Michel Paquette]

Back in 2008, I poste 2 threads looking for help before starting to build my scaled model of the Glen L Marine 50' cabin cruiser. In the Glen L catalog it's called the Klondike.
Needless to say, since this was not to be a "Speed Boat" that would achieve 40+ MPH, not too many people asswerd the threads. One even suggested to use a "trolling motor"

Well I ended up building my model at a 1/9 scale. It is about 65" long and weight in at 43#.
Since this semi-displacement hull, I can't use the "power calculator" that I found before writing this thread.

I have attached 4 pictures. One shows the hull under construction, one show the final product, one shows the motor I used to power up the boat and one shows the original installation with an old 1969 Kraft RC unit and rheostat speed control I was using at first

The prop that I am using is a 3 blade 2 1/2" diameter. I can't remember what pitch it is. I can only guess at 2.25 buy roughly calculating the angle of the blade.

The motor is a 12V motor out of an automotive emergency pump and light unit. I gutted the pump and kept the motor and the gear that was driving the pump. It as a 1:5.8 ratio.
then made a shaft to joint the gear assembly to my prop shaft, As for power, a 12V gel cell battery out of a computer UPS pack

After using it a few years things got a bit hectic and I had to shelve the boat for a while. When I took it back out last year, my radio system had seized up and was not longer usable.
So my son in law, which had just started into RC cars and truck, passed me one of his radio system which had a "receiver/ESC' unit, a servo and the transmitter. Unfortunaly i was not getting the speed I had before, which was not very fast to start off with

doing a few test runs last fall, I was getting 1.8 Knots with the 7.2V and 2.8 Knots with my 12V. base on a "hull speed calculator" I found on line, base on my waterline length, my semi displacement hull should reach 4.7 Knots to mimic the wake of the full size boat at 14 Knots.

I kneed some input as to weather I should stay with a brushed motor but going to a smaller gear ration, or going to brushless with direct connection to prop, not gear reduction.


Michel Paquette