I've been researching electric outboards this winter and, as usual, have found that most of my big ideas have already been put into practice by someone else.
My first idea was that while mono hull boats have little room for batteries and solar panels, pontoon boats have lots of space and weight-carrying ability. Pontoon craft are all the rage right now and I have been impressed at what they they can do.
Sure enough, a search for electric pontoon boats on YouTube brings up production models on the market in Florida. But the higher-performance ones seem to rely strictly on shore-power charging of batteries which can weigh 800 pounds. On a pontoon boat 800 pounds isn't much of a factor.
Searches of solar-powered pontoon boats brings up boats with roofs covered from end to end with solar panels and then propelled with a low-powered electric motor. My little bit of experience with solar generation at the cabin makes me think both systems are missing the mark.
Nowhere is there as much sunlight as in a boat. That sunlight not only strikes from above but reflects off the water. So access to energy is not a problem. You just need to get it to the motor. The battery is slowing things down. You can only charge batteries so fast. That is why you have charge controllers on solar systems -- to keep from charging too fast and from overcharging. So why can't we have a system where the motor gets its energy right off the panels and bypasses the batteries? It could do both at the same time, of course.
And then there is the electric motor itself. I think it should be capable of at least two voltages, a higher voltage when the power is coming off the panels and then a lower voltage when running on the battery. Dual voltage electric motors exist right now, just not for boats.
The panels don't have to be on the roof either. They can be on the skirting below the rail. If the panels were the type that generate electricity from either side, a boat could get twice the electricity.
Pontoon boats that charge their batteries from shore are just substituting batteries for fuel tanks. That's a waste when the boat is flooded with sun -- read that electricity -- while on the water.
I think solar boats should be able to go faster when there is lots of sun, just like a sailboat does with wind.
I'm telling you, the power coming off solar panels is incredible.