I pulled the stern (white) light from my dad's bigger boat (26ft Sea Ray w/ a Ford 460) and it looked like a standard automotive bulb. It had the round metal base with 2 solder blobs on the bottom.
The fiberglass rolls over on the sides, creating a pocket where wires are run. I'm considering using flexible, cuttable light strips for interior lighting by placing them in that pocket:
Ahhh... you are not on a local lake where they only want to see something lit up. I've seen the local park rangers take a flashlight as an OK boat light.