I got it on ebay, just typed in RC boat gearbox, loads came up,

where did you get the gearbox. I have an old open spur gear Dumas gear box that works well but is very noisy and would like to replace it with something that is quieter if that is possible.

Hi Colin, in 1991 I has a double Discoidectomy, on L4-L5 , after suffering for two years, throwing spasm fits and getting kicked in the butt from a mule every 5 minutes trying to walk.
Life has been great ever since, you should do great.
I have set of plans for the HMS Snowbird Corvette, which I could get blown up to any larger scale if you were interested.
Cheers!

Thanks Guys, for the response
Ive bought a 2-1 gearbox, and may go with a smaller prop, currently a 40 mm triple course one, (no idea of pitch)
i also think, theres no escape for heat in the engine room, posh word for electric motor area!! so perhaps some ventilation is required as well, so a PC fan, has been nicked, to aid in exporting heat

steve

A motor can run off a range of voltages but it has a max rating regarding the power it can produce. This is measured in watts and is the product of the voltage applied and the current drawn. So 12v times 5amps = 60watts.
Increasing either voltage or amps increase the wattage and if you exceed the max the motor will overheat. I suspect your coarse prop is the problem as it is overloading the motor and increasing the current draw. If you change the prop to a smaller diameter and less pitch it will reduce the current drawn and your model will perform much better. Three bladed brass props will give good results and I would avoid the two bladed racing props. As a general guide the prop diameter should be less than the diameter of the motor casing.
It is a case of trial and selection so good luck.
dave976

It is actually not the voltage that kills but more the Amperag the motor draws. Can you put an amp meter in line to the motor, boat in the bathtub, and hit the throttle to see what amperagevthe motor draws as Sherman's the water fly that would tell you for sure.

Thank you for the reply,
But if the 540 is a 4.5-15v motor, (it says that on the motor) how can a constant 12v be a problem?

I would like a gearbox, but have no idea of were to get one, unless i make it,

I think your putting to much voltage through a 540 motor without gearing I run an old robbe pt15 it has I beleive a robbe navy motor geared 2.1 I think with a 40 mm x Prop battery for that is 9.6v and that chips along

Hi,

Yep, its direct drive, and the prop is quite coarse, but weirdly, i was thinking more akin to a 2-1 motor to prop gearbox, to relieve the moto speed but increase the prop speed,

but what do i know. obviously, NOTHING !

Without knowing your Prop size, and guessing you are running direct drive motor, if your boat is of any size at all, this definitely would put a strain on a 540 motor- which are often rated for 6 to 9 volt operation.
Choices aren't go with a Hi-Torque 5000 rpm 775 Motor direct drive, or add a 2:1 or 3:1 gear reduction to your existing motor.