Building a solar/wind powered cruiser

[cameron82]

Been looking into building a electric cruiser .With the advancement of solar and lithium batteries the project is looking more viable .Has anyone have a diesel /electric system on board .My goal is to run a few wind turrets and cover the decks in solar panels .With a large lithium battery bank and maybe some lead acids .The idea is still in its infancy but would love to hear your thoughts on the matter

Also have heard about solar sails that can produce power but yet to actually see any specs or pictures of them .I know its possible but is it viable

So hoping to build a telsa of the cruising world your advice would be much appreciated

[valhalla360]

Search the forum for electric boats. Lots of discussions.


If you run the numbers, you will find it's quite viable...if you drastically reduce your assumptions regarding performance and raise your budget.

[dlymn]

If I was to completely cover the unused space on my 38' boat, I would have about 12 square metres. Using flexible panels and in sunlight directly overhead, I might generate 8 kw at the maximum. If I then take into account sail bag shading, sun angle, rocking and rolling etc, I might generate 5 kw I might get that for 5 hours on average, but that's 8 hours in summer and 3 hours in winter. With or without storage, that will not drive your boat very fast. I get a maximum of 8 knots out of my 36kw diesel. your solar panels will not provide sufficient power. You will not be able to motor on cloudy days, before 10am and after 6pm. There have been recent warnings about frequent walking over flexible panels as the eventually suffer damage, You might easily damage the panel with chains and shackles even a flicking line. I read somewhere that they really only work well when there's an air gap behind them to allow air circulate and cool.
Your storage batteries will not help you much. a 200 amphour lead acid stores 1kw of usable energy. If it was a lithium battery, it would store 2 kw. If you had 36 lead acid batteries on board, you would be able to motor at 8 knots for one hour. It would take a whole day to recharge the batteries assuming you have a 5kw charge controller. Those batteries would cost you about $10,000 and might be good 3-5 years. Lithium last longer but cost much more. The lead acid batteries add more than a tonne to your boat. Lithium maybe 500kg. Remember, this is for one hour of motoring, maybe 2 if you take it easy

It's much the same with generators. On a sailboat there is little energy advantage having diesel electric over straight diesel. You consume the same amount of diesel to do the same work. There are inefficiencies with any energy conversion and storage that increases the energy demand. Remember too that a kw is a kw whether it's produced by a diesel or an electric motor.

Don't cite cars like the Prius; they are petrol cars that use an electric motor to start from rest but not much more. There are plenty of cars around that get the fuel consumption of a Prius. Remember too when comparing cars and boats that the energy transfer on a boat is by water propulsion and that is very inefficient. I use 4 litres of diesel to travel 14 km when the same size motor will propel a car 80+km on the same amount of fuel.