Thanks for the welcome, I only hope I will have the time to participate properly.

It seems to me a catamaran configuration is best for a solar boat - good stability while providing maximum surface area for the solar cells without the drag of a wide hull. Many full-size types are like this, but it raises the problem of propulsion in a model. You wouldn't want the power loss and complexity of a long drive shaft or outboard arrangement, so perhaps a slim brushless motor in each hull would be best.

I felt my ears burning so I thought I'd better join your forum and post a public reply.

As Roy has mentioned, my name is John Parker and I write a regular column for Model Boats magazine called Flotsam and Jetsam.

The solar powered RC boat I designed for the magazine took the form of an old wooden ferry with solar panels on its roof. It was designed above all with efficiency in mind - long slim hull for low drag, large propeller, 300 kV brushless motor. There are 15 solar panels on the roof, each rated at 2v 0.25A connected in series-parallel to give 10v at 0.75A (i.e. 7.5W). Scale is 1:25, size about 854 mm x 152mm and weight about 3.25 kg.

It has two modes of operation, solar powered only or solar with battery back-up. There is no problem in mixing with other boats on sailing days - the power is enough to drive it at 'hull speed'. On solar only I believe it would be able to keep moving slowly in light overcast, but be stopped dead in heavy overcast. Of course, the sun always shines in Australia so I haven't been able to test that out!

John