Check the compression post, most are not good. replace it with one single post from ceiling to the keel. You will have to cut the corner of the shower pan to get it in there. save the parts of FRG to remake said corner.
Check the all important bulkhead where it is attached to the old post for rot replace as necessary being sure to epoxy the new materials together. If you cut it back overlay the repair with marine ply marrying the old to the new and again epoxy it together. If the deck has sagged you will see it in the door frame. Make the post long enough to push the deck back up where it should be.
Replace thru hulls with fiber reinforced plastic and replace the rotted wood backing too.
I have been rebuilding mine for years and know where some other improvements should be made. write to
jameshandzus@outlook.com
