DON'T DO IT!!!!!!!! I didn't have any choice. Mine were showing signs of leaking. Some of the screw caps were cracked. This is caused by RUST! The backs of the screw caps are metal and rusting. That causes the caps to split and rust trails run down the ceiling. Mine is a 2002 and things are ready for rebeading.
The first thing you need to do is remove the 3 1/4" screws holding the rails on and throw them away. They will not fit when you done. They srink!!!!!! Accually, when the factory installs them and tightens them up, they compress the cabin top. They cut the screw off to allow for the screw caps to fit. Thats why you can't use the old screws. The top is now NOT compressed and the screws SHORT. Go buy TEN #8 x 3 1/2" screws and TEN screw caps with Plastic backs. Sand, seal and reinstall.You will also have to cut the screws off.
I just removed all the exterior teak on my Sun cat and redid it with Sea Tal. Did not have the problem with the bolts that you had. Some of the screws needed to be cleaned up on the end were they had been cut off so the nuts would start on easy.
Forget the screw idea, screws are for young lovers, use a ss bolt, washer and loc-nuts with a UHMW or aluminium backing plate below deck. Additionally I placed a 1/4 inch UHMW shim under each stanchion above deck, and of course my favorate 3-M 5200 slow set goop stuff. "Stiff like a wedding you know what."
skip.
I redid mine using Lifecaulk, but sealants isnt anything to go to war over..... LMAO
I didnt use those damned caps..... I went with washer and regular nut (SS) and a cap nut (SS)
All hardware I use is SS.
Mac