We love to anchor out, but still like the modern conveniences like electric light in the evening. One of the problems with using electric lights, is running your batteries down in the evening, and then having the CO detectors alarm. If the voltage gets too low, they will start sounding an alarm. After being awakened a few times by 3 of these units, beeping in unison, we soon learn to make sure the batteries were charged before going to bed. One way to keep the batteries in a good state of charge is to use less electricity for lighting. Rick Gilbride, a Mainship 400 owner, has a great solution. Rick has replaced many of the incandescent bulbs in his boat with energy efficient, long life, LED's. While these are available from West Marine and other marine suppliers, Rick has found a very inexpensive supply for these bulbs: http://www.superbrightleds.com
Rick suggests the #3022-4 festoon bulb at $2.84 each, will fit all the courtesy lights in the stairs and cabin. This bulb at West Marine retailed for $29.00 each as of this writing. He has also replaced all the 12 volt distribution panel lamps with LED's, found at the same site. The lamps in the distribution panel are proned to rapid burnout, so 10,000 hr LEDs are a great upgrade. Be sure to check the bulbs in your boat for compatability, before ordering LED bulbs. Mainship may have used different fixtures in different model years.
Another source for LEDs is http://www.niceledlights.com/