Is it just me or this this idiotic? There is already a wonderful alternative source of energy for powering boats--wind! What is the point of a solar boat going 5-6 knots? It is more expensive and not as fast as using sails.
=== author's response follows =====
Think in terms of commodity shipping. Barges and other shallow draft cargo hauling ships are generally not sailable. Small to mid-size cargo ships that ply inland waterways with narrow maintained channels have the same issue. This is a prototype that tests the limits and gets attention to yet another potential alternative to burning high sulfer bilge oil in very large ships. Plus it is fun.

Incidentally, marine fouling (barnacles mainly) typically cut efficiency by up to 20% on ships that can not be eaily drydocked for cleaning. Smaller can be more flexible in terms of where the ship can go, and how cheaply maintenance can be performed.

There are kites for cargo ships or plans to make them.
http://www.msnbc.msn.com/id/13325827/site/newsweek/

The most efficient engine in the world is a crude diesel. Not sure on emissions.
http://people.bath.ac.uk/ccsshb/12cyl/

This is very very cool. I can't wait to read more.

I agree that this appears idiotic.

Although, I would be interested to see a comparison of embodied energy of the solar, wind and diesel powered boats.

I'm guessing the sailboat would win. And just because diesel is "efficient" doesn't change the fact that these boats consume enormous amounts of fuel.
How much more expensive will oil have to be before people start lauding the "efficiency" of sail power?

People won't care about sail power or it's efficiency. When oil gets high enough and it costs the same to buy domestic product as it does an imported one, that's when any change will come about.

I think this is looks like an interesting concept. However as someone who has seriously researched a circumnavigation in a sailing cat I would have a number of concerns with the proposed vessel's seaworthness.

The first concern would be the weight of the battery bank. Weight is a catamaran's worst enemy and even a seaworthy design will quickly become unsafe for blue-water use if too heavily loaded. Batteries are extremely heavy, and a battery bank would absolutely need to be sufficient size for the vessel to avoid oncoming storms and maintain control during them. This could mean, perhaps, a week or more of clouds. Without a secondary power system the battery bank should be very large, thus very heavy, thus bad for a cat.

Secondly, that solar array is also quite large and in high winds (perhaps with spraying water and even large breaking waves), it would need a more substantial structure than what is illustrated to hold it in place. If it were to break loose it could hole the hulls or endanger the crew, in addition to robbing the vessel of its only power source.

Third, the handling aspects of the vessel during high winds will be severely hampered by the unusual windage that array generates. Sailing vessels have time tested means of coping with storms and the windage upon the rigging. But, can this cat really be expected to lay well hove-to, or to run off in storm conditions?

There are obviously more considerations. For many passages, even with the design as I understand it, she would make the crossing fine. But in a storm...

Building tourist boats for inland waters is one thing. Making a safe and sane blue-water vessel is quite another.

To address the questions of cost. The array might actually cost LESS than traditional rigging. I would expect it to cost at least $75k for spars, standing rigging, winches, running rigging, sails, etc. Now the batteries, if exotic to save weight (Li-poly) might well cost more.

I believe that there ought to be a shipping company brave enough to try out one of those cargo ships that have sails on them. People are brave enough to try out hydrogen in cars, even though that's far from mainstream. The Air Force is brave enough to test Bio-Diesel in their aircraft and that isn't mainstream in the airline industry. So why not have a shipping company try this? Why not have ships running on Solar or Wind, or a combination of the two? Just because it's not easy shouldn't be a reason not to try it, especially when it's suggesting a fuel source other than fossil fuels.

Sailing boats are expensive to build and operate. They are dangerous in difficult conditions and cumbersome to use in confined waters, and of course, don't sail directly upwind.

Romantics continue to use sails, but they died for practical use in 1900.

Solar panels are still prohibitably expensive. Most applications are in extreme conditions or where the costs are artifically subsidised.

This type of experiment adds little to our understanding of photo-voltaic use, and without a secondary supply of power or power storage, its an unseaworthy boat.

If the boat is to be powered as shown with a large flat panel above a very conventional catamaran, the exercise seems rather pointless since few would want to use such a contraption.

The boat should be re-designed to take the solar panels as part of its normal structure, and personally, I'd seek a higher cruising speed. Five knots is inadequate for an ocean crossing. Allowing for lack of power overnight, its practically what can be achieved by drifting.

There are still experiments worth doing, but really, the efforts should now be transferred to commercialising the known techniques.

It's always interesting to read comments from armchair know-it-alls, but the truth is that this is an historic event which will be remembered by future generations who have to bear the brunt of this generation's insolence towards energy use, even if the poignancy is lost on these readers. Whether you wish to pick apart the nuances of the speed of the vessel or its design matters none; the point is that this first crossing will prove that it can be done, not unlike other famous transAtlantic expeditions before it! Would anyone today question the relevance of a 30+ hour solo flight in 1927 in a small plane without even a forward windshield which was almost too heavy with fuel to get airborne? Or was that an "idiotic" exercise too? Or how about Leif Erickson proving that there was another world beyond the shores of Europe? Idiots, of course. Einstein had a series of great comments about people who fail to see the importance in creative thought and actions.

This first crossing will expose solar boating to the world as the great method of water travel that it is. As a person with a great deal of personal expertise in this, I know.

the truth is that this is an historic event which will be remembered by future generations who have to bear the brunt of this generation's insolence towards energy use

Really? So we're depleting the wind?

Something sure seems wrong with the math on the Transatlantic 21. http://www.transatlantic21.org

-Motors: 2 @ 8 kw each, 16 kW max
-PV: 10 kWp, mounted horizontal
-Battery capacity: 512 @ 48 vdc, 25 kWhrs
-Weight: 12 tons
-Claimed rate of travel: 4-5 knots, 24 hours per day

Assumptions:
Highly efficient battery type will have 1% power loss recharge.
Maximum battery DOD: 70%
2 kWhrs power for communications, electronics, water pumping, lights, etc.

24 hours of operation (claimed):
If we there are 37 kWhrs (39 – 2) available to power the motors divided by 24 hours, we have 1625 watts or 812 watts per motor average. I have a $49 electric chain saw that uses 1000 watts power so I doubt it is possible to move a 12-ton vessel at 5 knots with just 1.6 kW!

If the batteries are cycled to 70% (short life), there is only 17,500 watts to run the motors for about 18 hours. That’s only 972 watts or 486 watts per motor.

I read somewhere that about 750 watts electrical power is equivalent to 1 HP. If this is true, they are claiming to propel 16 tons @ 5 knots with a 1/2 HP trolling motor. I want one of these motors!! Imagine the electric car you could build.

Here’s a more realistic assumption. If the vessel can cruise at 25% power, it will use 4 kW or 96 kWhrs per day. Even more realistic though, at 50% power that is 192 kWhrs per day. Umm, maybe. But, the PV panels can only can make 37 kWhrs.

There is no way that this boat can perform continuously as claimed. So either I can’t do the math or they are up the creek without a paddle.

Monte Gisborne, of the Tamarack Lake Electric Boat Company sends along this message in response to Larry's calculations.
---
Firstly, the capacity of the traction battery isn't as relevant as he suggests, but the peak capacity of the solar array is critical here. Remember, the battery is strictly for storage of the electrical energy provided by the solar array and only needs to be big enough to store enough energy to get one through the night and times of heavy cloud coverage. The capacity of the battery correlates with the size of your gas tank - it really only has to be big enough to get you to the next gas station and it really does nothing to get you there, the engine does all the work.

You'll note that the chosen trajectory takes Sun21 across near the equator where average daily solar availability is quite good, around 6+ hours per day. This yields a minimum about 60 kilowatthours of energy per 24 hour period (6 hrs. X 10 kW), which is substantial and represents the critical data required. This equals about 2.5 kilowatts or 3.5 hp on average, continuously, not the 1/2 hp reported below.

The next consideration being ignored below is the "cube-of-speed" law which plagues all naval vessels and even automobiles. Simply put, it takes about 8 times the power to go twice as fast for any given vessel traveling in water. Simply put, it takes very little power to get a boat going - but it takes walloping power to make it go twice as fast! I don't claim any accuracy for the data on Sun 21 listed below, but 3.5 hp would push an efficient hull design like the Sun 21 along quite nicely, just not quickly. Four to Five knots does sound a little quick, but not that far off. Imagine 3.5 horses pulling this vessel along a shoreline and you'll get the picture. The 2 kilowatthours of energy for electronics and lighting sounds very high, I would have assumed much less than that especially since they would be using their equipment sparingly (I would assume) and LED lights and other efficiency products would prevail throughout.

Also, a discussion on the reduction of Peukert's effect here would be in line. Perhaps the greatest benefit of the solar is that it greatly reduces this effect and generously help to increase the actual (versus rated) capacity of the batteries while the boat is moving. The reported 512 amphours may actually be a lot more if the actual draw is minimized by the solar modules.

Favourable currents and winds also need to be included in actual speed calculations.

Some anonymous said that, looking at his 1KW chainsaw, he cannot believe a 12t solar boat will not move at 5 or 6 knots with 1,6KW.
By the way, he is welcomm to see a 60t solar boat, with 80m² of solar pannels, moving at 5kmph on the Canal du Midi, in France.
I was on board looking at the control pannel, and it needed only 5KW to move at this speed, which is the highest authorized on this old canal.
The craft is called SOLEIL d'OC, and is a hotel boat fit to host andhicaped people.
5KW for 60t is around 1KW for 12t. Here you are!
And, yet, the shape of Sun21 is much better than that of SOLEIL d'OC, so her speed is bound to be better.
Good luck to them
By the way, I found on internet that a couple with a 38foot catamaran is following the same course, ahead of them.
Maybe they could exchange info?

Look at http://aftm.free.fr/NAVIRATOUS1.pdf to know more, in French.

Monte Gisborne above repeats the often quoted American fallacy that Lindbergh made the first transatlantic flight. This is NOT true. The first crossing of the Atlantic was made 8 years earlier in 1919 by the British flyers Alcock and Brown in a Vickers Vimy biplane bomber which took off from St.Johns Newfoundland and landed at Clifton, Ireland.

sails moved cargo very well for many years, but speed is the problem the project faces over fuel, wind or solar. many of the products moved trans ocean are time sensitive. also at five knots its almost unsafe to have a ship that heavy in a storm with no power to fight the sea and wind. oh go ahead and argue that many have made it at slower speeds etc. with no problems yada yada, find a crew for such a boat that could be helpless so easily- and then load it down with tons of cargo and see how it goes. heres an idea use solar in place of the power generators that normally run on diesel fuel or fuel oil. they often run the whole time a ship is at sea and solar could save some fuel and still power a few things on the vessel. fuel price is also not a factor, people will use it and pay for it no matter the price until its way out of control and they can simply no longer pay. look around we are doing it right now! ten years ago i would have said you were crazy if you said i would pay over three dollars a gallon for fuel but now i do it without thinking about it except that i am almost broke . fact is people will not want to slow down to save anything. some may but not the ones buying the products being shipped and sold. out of sight out of mind, most will not worry about the issue when they are viewing the new flat screen from hong kong or some other far off port. trying to force a little savings of fuels and the planet and pocket is great but in ships? come on, be realistic factories and manufactures, mines etc. hurt the world far more and waste materials like crazy. then leave behind eco nightmares to be fixed later if ever. take a look at epa superfund, ships will be the last on the list. no i am not saying stop the manufactures or anything like that so dont attack me on that one either. what im saying is clean up the process at these places make them a little better for the world and cleaner for the place they put behind. many times its all about money and production. maybe some solar power at work would help cut back with out a problem. led's might save some electricity things like that are basic and over time would make a difference. i am not always correct and dont claim to be now but i feel that the answer for fuels etc. is there but the problem is we have not been forced to get it and make it work. example, we got nuclear power working for us fairly fast when we feared the enemy would use it against us first. now it powers thousands of homes and ships etc. if we had a real crunch and major major need we could work with things like solar power and wind etc to get away from fuel but the hard to face truth is the world is not wanting it bad enough. i wish it would

What I don't quite understand is the efficiency of the solar panels but then I might be missing something:

- A 10 kW array over 65 m2 = 154 w/m2

- Assuming typical incident radiation of 240 w/m2:

- Efficiency = 64%

Which is far higher than the ~30% achieved by GaAs cells in laboratories! What have I missed???