, 80 square meters of solar panels sound wonderful but I own a catamaran
and my sails are always vertical and actually present very little surface area to the sun during peak solar hours (0900-1500) I suppose I would be able to take advantage of those early morning and late evening hours I don't get to use now. I guess there are times when it's an advantage to own one of those tilty boats. You guys aren't proposing to start building your boats so they tilt are you? Maybe a mast
that tilts to follow the sun would work?
The way I calculate it, my cat requires about 40 KW or 30 HP to maintain 6 knots, I would therefore need 40 kilowatt hours to cruise at 6 knots for 1 hour, or be collecting 40 KW from my solar panels. Even if the electric motors were twice as efficient as my diesels(no transmission
losses etc.) I would still need 20KW. At 10% efficiency (actually a quite high average as solar panels are rated only perpendicular to the sun)I would need 200 square meters to move my boat at cruise speed. I could of course store some of that energy in a battery bank while sitting at anchor
for a long period. I calculate it would take 16 4d AGMs to hold that much capacity at a 50% maximum discharge rate. If I covered the entire usable upper surface of my boat with solar panels I could get about 50 square meters, so every 4 days I could capture and use enough electricity for 1 hour of cruising. Even if I stored electricity generated from the motor
when I was sailing I could still only cruise for 1 hour. I could of course increase the storage
capacity by adding more batteries. Those batteries weigh abot 2000 lbs per group of 16. So if I wanted to be able to cruise for 5 hours I would need about 10000 Lbs of batteries ( even batteries with twice the storage capacity/lb as lead acid would weigh 5000Lbs). That should inhibit my sailng performance just a bit. Of course it would take me 20 days to charge these batteries so I could still only cruise for 5 hours every 20 days. There is actually still a bit of debate on the lifetime efficiency of solar panels, that is that current
technology requires more fossil energy to construct than they will collect in their lifetime. My diesels on the other hand weigh about 1000 Lbs and using approximately 600 Lbs of fuel will produce 6 Knots on my boat for about 100 hours and I still get to use my deck
. I don't think that solar electric propulsion
even when augmented by regeneration while under sail will ever make a practical substitute for a fossil fueled engine
in the cruise mode. I think the solution is the use of alternative fuels such as biodiesel to power these engines so that their use is carbon neutral.
The most advantageous alternative propulsion
invention I can think of would be a sail configuration that allows one to go directly into the wind, since a major reason I use my engines is that the wind is usually coming from where I am going.