This whole 'power' business is difficult to get you head around - because we are all a bit old fashioned...? If you look at all of the long distance racers they have a generator on board to power their instruments and self steering gears... And carry enough fuel to get round the world on the genny!!!

Now assuming they know what they are talking about - and I think they do - they have worked out that an engine is a better method - via a smart charger - to keep the batteries up.. Ok you need to put it under load if possible but none the less I found with the exception of the Galapagos to Marquesas (longest possible passage without touching land) that I always had enough fuel for the main engine to run it as a genny for an hour a day... Added to that the cost of these items - wind gennys - solar panels, towed gennys - is very high.. Think of how much diesel you must burn to get any where near the cost..

I do think a blue water boat needs a back up way of getting amps into the battery so a solar panel or two is probably the way to go... I think.

Michael