Get yourself an external battery for computers. There's one on this page that will power your Macbook for 16 hours. The MPB-100. http://www.hypershop.com/HyperMac-External-Battery-for-MacBook-iPad-iPhone-USB-s/91.htm ( or other battery )

Second,,, get yourself a smallish solar panel that is made to charge car batteries. http://www.emarineinc.com/categories/Battery-Charging-Solutions/?gclid=CJqa3_W7y6cCFYPd4Aod_QtSLg

Now you can run your computer all you want by keeping the external battery charging whenever there's sun with the small solar charger. Your off the grid and there's no grief from the other guy. If you do some research you can probably work out a system to even charge the camera batteries, flashlights,, etc. It now becomes just math,,,, purchasing the right combination of solar panel to charge the battery during the day. The small solar panel can also be used to trickle charge your house battery bank when you're away from the boat. (that might be a point to make to justify the cost of the system.) That way you can argue that you're only buying a battery,, the trickle charger is really for the boat.

The full system wouldn't be cheap by any means,,, probably in the neighborhood of $350.00 but the issue will be over. You'll keep your Mac charged and running all day and when your away from the boat the house bank will be kept up.

Yeah,,, I like the idea of the external battery and solar charger.

Rey's not here. She'll probably meet Steve (From Brendon) and I in Belize City. She's trying to figure out what to do with our 23 year old cat 'Boo'. Boo is too old to go sailing anymore. She should have been dead 3 or 5 years ago as cats don't live 23 years. It's kind of sad and funny at the same time watching her get pissed off and grumble because she can't climb up to the bed anymore and needs help. She's just not ready to kill yet.