Major props to another batch of crazy Euros with an environmental bent. These folks are taking off to cross the Atlantic in a Solar powered skiff, that looks more like something I once rode on a booze cruise somewhere in Missouri. Here’s the news release:
On Monday, 16 October 2006, the catamaran was officially launched by Federal Councillor Micheline Calmy-Rey. At a ceremony that took place before an invited audience the boat was christened “sun21″. At 7 pm it set off from Schifflände on the world’s first solar-powered transatlantic crossing.
The journey actually starts on the rivers of western Europe, before working their way through the English Channel, down to Gibraltar, over to the Canary Islands, across the Atlantic to the Caribbean, well, just check out the Map here.
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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, but I doubt it. At 50% power that is 192 kWhrs per day. The solar 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.
OK, so I’m the one up the creek. Will someone please explain how they accomplished this with the limited power they had on board? I keep going over numbers and assumptions but nothing works out to resolve the distance/time thing. Is it me or is there a new math?
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