Hi Peter,
That's a nice thoughtful gift for your Dad. Unfortunately, it isn't as easy as it sounds. Since the boat is 30+ years old, even if there was documentation on what was shipped with the boat, there's no guarantee that that is still the case.
Electrical stuff is the first thing to go in the marine environment. And upgrades to lighting are common to reduce heat and amp draw. First with flourescents and now with LED's.
So you really need to do an inventory of what's there. If they are standard 12v bayonet mount bulbs (like what used to be overhead in your car), you can easily find replacement bulbs, and maybe someone here can provide a link for you.
We had a lot of failures when we first went with LED bulbs. We found they were expensive and failed frequently.
What we ended up doing on our boat was buying these (for most of the fixtures).
G4 Ultra 9xHP SMD 12-24VDCor you might take a look at these, they have more LED's for less price (probably newer model of same thing we bought in 2011)
G4 19 LED Light 10-24VDCThen you open the light up, cut off the "holder" for the old bulb, and wire in these things directly, secured with a dab of hot glue or something. Not as clean as buying your stepdad a handful of bulbs for sure. But maybe cheaper and maybe better bulbs (the words "current controlled" on the descriptions is important, because the boat voltage can fluctuate a lot).
Make sure you get the WARM WHITE color. The non-warm white is glaringly white.
We have also replaced our flourescent lights with strips of LED lights.
Maybe someone else will come back with a easy link for you.
Googling "12v bayonet mount" I came up with this link:
https://www.superbrightleds.com/cat/bayonet-bulbs/But you still need to figure out what your (most common) light fixtures are before you buy, and what the socket is. Also one more warning from these cheap LED places... most are in Hong Kong and delivery is not 3-5 day as you'd expect.
Good luck.
Sherry
