On my 1999 SO 45.2, the ceiling panel next to the compression post under the mast became wet and rotten. I removed it and am trying to figure out where the water is coming from. I assumed it was leaking around the wiring from the mast, but that was dry. I found holes about an inch forward of each of the bolts that attach the mast collar. I probed them with Q-tips and found that they were very wet and very dirty with mildew. They seem to go all the way through the cabin top, but I cannot confirm this since they are under the mast collar. After I cleaned and dried them, they don't seem to be leaking now, even after a moderate rain shower. I am monitoring it for now, but my question is, Why are these holes there? I am tempted to fill them with epoxy, but I want to find out if there is a reason for having them there. They seem to be about the same size as the holes for the mast boot bolts. It almost looks like someone at the Jeanneau factory drilled holes in the wrong place, did not fill them, and then redrilled them in the right place. That couldn't happen, could it?
I had a similar issue with my 2002 SO37. On mine there are 8 bolts total: 4 are for the mast collar and 4 are for the compression post. The post bolts are offset from the mast collar bolts. My leak was coming from the after starboard compression post bolt and when the mast was unstepped I discovered there was nothing protecting the bold head from water (hence the leak). Not sure if it helps but after rebedding the mast collar and copious amounts of butyl tape she's dry in the heaviest of rains.
I have a 98 45.2 and these had issue with the mast and collar compressing the cabin top. I had to remove the mast, cut out the step and remove the rotted wood above the compression post and replace with aluminum plate, I say this because it would be easy to offset the collar from it's original position and leave the original collar bolt holes. This may be what your seeing if yours was ever repaired. I can't think of any good reason not to seal yours up. Mine also leaked around the wiring but that caused water to stain the ceiling panel right inside the V berth
Malcolm, the articles about the mast step repair and the wiring solutions were excellent. Thanks.
web, Thanks for sharing your experience. As far as I know, there were no prior repairs to the mast step. If it had been repaired, the core should have been replaced, and the holes should only go through the ceiling layer of fiberglass, not the core. The Q-tips are going in at least an inch into the holes. I have owned the boat for 7 years, and the rigging has been very stable without needing to be tightened.
I think I will epoxy the holes for now and plan to remove the mast for next winter storage, so I can check it out further.