do you have a fuse block under the dash or in engine compartment? My 1994 Sea Ray 200 Overnighter has a fuse block on the underside of the dash. I can see it clearly laying on my back looking up into the console. I have a mini ATC type fuse for Nav Lights. Does your stern light work in the Nav switch position but not the front/side colored lights? No likely the fuse or the power from the battery if the stern like works but not the bow light.
If they are not working you do not have power to them..check bulbs, fuses, continuity etc. Should not be too difficult to trace problem..sounds like a common issue to your electrical 12v DC supply to nav lights
