Hi Red,
I have a mostly pure solar powered trimaran, although its primary propulsion is from the wind rather than solar panels. And wind is of course solar powered, just one step removed. The electric propulsion is for getting on and off mooring or anchor, and sometimes for navigating channels too narrow to sail.
So far the motor is mostly powered from the sun. But I do have a backup genset, being the smallest honda generator of 1kva. I have used it occasionally to top up.
Most of my solar power is used for domestic load. And what's left over goes to the engine batteries.
I have some nice low profile solar panels from Solara (on the expensive side though) which are on a stainless steel plate which can be curved slightly, and they have a walk-on surface which means usable deck space is not lost. They are mounted in low traffic areas. Those panels amount to 300 watts, and I have another 140 watts of flexible panels which I roll out when at anchor or the weather is light enough to have them out when sailing. I'd really like more power than this.
the bottom line is that the solar power I have equates to somewhere around 15 minutes of motoring each day at 1000 watts - which is around 4 knots. and even that requires careful managing of my domestic load - not too many movies, or adventures in the electric powered dinghy. I've lived aboard for 3 years, and she's only been attached to the grid for a few days in that time, and another few days have seen genset use. But its only in the past 6 months that i've had a reliable electric motor so before that the demand was primarily domestic.
If you could find a way of keeping the rig and sails, that would help you reduce the demand on the motor. Perhaps you'd need to consider mounting the mast foot in a tabernacle so you could lower it if you plan on doing canals with low bridges.
could your cruising include longer stopovers so you don't need the 4 hrs or so of motoring each day? in that way you have more time for solar to replenish your batteries. if you could cruise every second day, it effectively doubles your solar power thats available for propulsion energy. that is, after your domestic load is accounted for, which will be there every day.
for the times you need to do the 70-80 miles could you have a small genset on board? such an indulgence would also cover for those occasions when there's a series of overcast rainy days.
others have already given you some figures for solar panels. what I notice is that the maximum power I see is around 250 watts, and its more likely around 150 watts. Which is way less than the nominal 440 watts I have on board. This reduction is due to a number of things - the main ones are the fixed orientation of the panels and shading from the boom and other parts of the rig. Even the movable flexible panels can be considered fixed. I rarely move them about to follow the sun better - even though I imagined I might do this when I bought them.
consider lithium batteries for energy storage - they have lots of advantages for a purely solar powered boat and which means you'll recover much more of the available energy from your solar panels. you would would have seen discussion on this topic since you've been following this group for a year now, and there's something about it on my blog at
http://currentsunshine.com/?page_id=10
have fun with your electric adventure
cheers
chris
On 04/04/2010, at 2:21 AM, peoria_diver wrote:
Hello all,
I've been lurking in this group for the past year or so and have learned a lot from you all. I've had a project in mind and I'm trying to figure out if it's practical and how to make it work. Would it be possible to modify a smaller cruising sailboat to a pure solar powered boat?
My thoughts were along the lines of buying a sailboat around 30' LOA, stripping out the engine, mast and rigging, fuel tank, etc. and replacing it with an electric motor, batteries in place of some of the balast, and as many solar panels as I can fit on the cabin top and on a hard top to replace the bimini. Most days I'd like to be able to cruise around 5-6 knots for 4 hours or so, but still have the capability to go 70-80 miles on occasion. Oh, and the maximum budget for the project is about $40K.
Is this possible? Practical? Safe? And how would you accomplish it?
Thanks!
-Red
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