derbyrm wrote:

But remember that you lose about one half volt thru the diode. For
incandescent light bulbs, the change from 12 volts to 11.5 is significant.
Better have bulbs with more than the required range/brightness.

Or use LEDs as bulbs - they have the diode built in (actually, they *are*
diodes). As a side effect, you get more light for the same amount of
electricity, which translates to a longer battery life. May not be a
problem on a motor boat, but on a sailboat it may make a difference...

-Heikki