Hit a submerged chain. Back in the yard, an examination revealed that the f/g bulb housing had been holed. Attached pictures of before and after repair. The kelp cutter slot was smashed closed. I used a disk on a dremel to recreate the slot and tweaked in the gap with a flat blade screw driver. Also noted that there is a 1/8" space between the f/g skin and lead in this area. I filled in the patch back to the lead. Then sand and paint.