Give solar panels a try
I have not-so-fond memories of having to run the inboard diesel engine on a charterboat three or four times a day to charge the batteries and cool the holding plate in the fridge. It was OK while motoring, but it was no fun sucking up the exhaust fumes swirling around in the cockpit each night before going to bed.I recently had the chance to buy a motor with an alternator for my H23 and passed, because of the afore-mentioned memories as well as the additional weight and cost. With the money I saved, I bought a 10W solar panel, which I secure on the deck behind the mast when sailing. If the bimini is up, I put the panel on top.When I am going to be away from the boat for any length of time, I slide the panel into a sling I made under the main sliding plexiglass hatch i.e. inside the boat. Even with the tinted hatch, I still get 17+ volts (open circuit) which is more than enough to keep the battery topped up. My panel stays clean (sorry, birds) and dry, it is secure from theives, and it blocks a lot of sunlight (keeps the interior cooler and preserves the upholstery). The idea of mounting it in the cockpit down between the seats is good too (keeps it away from prying eyes).Peter Suah "Raven"