tdw wrote:
First up you should check the size of the wiring up the mast. If it is undersized
you will have severe voltage drop problems and this will contribute to the
lack of reliability.

Undersized wiring with its associated voltage drop just means the
lights will glow less brightly, and may not meet Coast Guard
specifications for brightness. Incandescent bulbs *like* lower voltage
and last longer. Shouldn't affect reliability. Assuming it's not also
crappy wiring with compromised insulation, or ridiculously undersized,
like 22 gauge or smaller.

Corrosion at contact points is usually the problem; check switches,
fuse carriers, connections, bulb mounts, etc.