Hi, The top part of my H16 pylons are corroded (where they enter the corner casting) and the bolt hole has elongated making the connection sloppy on all four corners.
This is the idea:
Fill the inside of the pylon with expanding foam leaving about 8 inches on top to be filled with a mixture of epoxy resin and chopped glass (sort of like SEACAST)
http://transomrepair.com/zk/
This will make a solid core of fiberglass inside the pylon on the top section, from where it exits the deck and flush on top of the pylon. Re-drill for the 1/2" bolt and wala! We have a solid pylon that wont corrode because its fiberglass core and a new and tight bolt hole to hold the corner casting secure.
cast the vent tube inside the pylon as the foam is being poured....
I considered what another member did, weld another extrusion inside the pylon and re-drill for the bolt hole. But this will eventualy corrode again, and the bolt hole will eventualy elongate again.
Added weight is not a problem as I wont be racing the cat. Besides this will only add about 2 1/2 lbs per hull...not a big deal to me.
any opinions??