Hi David,

They look like interesting craft, do you have drawings yet ? motor wise I would look at an 850 size brushed driving a 2 1/2" prop and a sealed lead acid SLA battery, as you will need some ballast.

Keep us posted, Regards Ray

Assuming that they are intended to go like fishing boats, something like a 540LM, or a 545, run on about 3/4 the volts on the label driving a prop about the same diameter as the motor can.

A heavy SLA battery helps with ballast, on the other hand a lighter battery such as a NiMh lets you put the ballast where it is needed and gives more opportunity to choose the voltage that you prefer.

Building heavy is not always the best option – there was a case in one of the magazines many years ago where the builder had a fixation with ultimate strength. He was upset when he found that it floated below water line before any working bits were added, and that rather than a working model, he had a rather nice display only one.

Edited By Malcolm Frary on 04/03/2021 17:29:28