Bill,

I was able to find on-line the Aqua Signal official replacement outer ring and gasket (gasket goes on the inside of the bulb to keep the electrical connections between the bulb and the mast wires dry) for our mainmast downlight, the pieces that went overboard on Harmonie. The outer ring holds the bulb in place, and works by a push and turn (i.e. bayonet mount) mechanism.  As others have stated, the foresail (or spinnaker halyard) may rub against the housing and spring the outer ring free.  Therefore, after several additional replacements, I finally used a thin layer of semi-permanent silicone caulking when attaching the outer ring.  Hasn't come apart in over a year now.  Of course,  I'll probably need a razor blade to cut the silicone in order to replace the bulb when it finally burns out...

Derick Gates

SM2K #400 Brava

Currently on the hard in Bailey's Boatyard, Falmouth Harbour, Antigua