No matter how you slice it we use energy and materials to build and maintain boats. Those need energy, too. I'm not talking elbow grease here. Products need energy. I recently, in the desert, installed solar panels on my camper van (I say "I" advisedly as I had a great deal of competent help) and it is sweet to have the sun run my fridge and lights!! And of course, back now in the PacNW at bro's hangar and hooked up to 110.

But, you are right on about sailboats. Of course, I abhor generators, fridges on boats, air conditioning on boats, etc. So may not be the best judge..