Bulbs
Bulbs can be tricky to replace, as the previous owner of the boat may have replaced the fixture. Best to remove the bulb and go shopping with it: West Marine, local chandlery, electrical supply house, etc. Check some of the other bulbs in the cabin and see if they give you any more clues (i.e. wattage). Besides rating, you'll need to match up the pins with a replacement to ensure it will fit (and determine if they are halogen or incandescent). Sorry I don't have contact information for any local electrical stores for you. If you can't find a store to do some comparison shopping, you could make some phone calls (include dimensions). West Marine electrical link below.Best of luck,Trevor