Swim grid repairs...
Hello, Get a long 3/16 to even 1/4 drill bit...drill thru from top and thru headliner roughly in centre of soft spot...get a piece of aluminum or heavy plywood, drill a center hole in this, a piece of 1/4' threaded rod, some fender washers and nuts, some PVA, some epoxy, some waxed paper and a piece of 1/2 to 3/4 dense sponge rubber or in a pinch some 'bubble wrap'...sound the spot with a small peen hammer to roughly get an idea of its perimeter...drill 1/8 holes around outside of perimeter thru top layer of glass and towards larger center thru hole...if you can, put a wick of cotton thru the center hole and let the area vent a bit...Spray PVA (poly vinyl acetate) over the area...see West Marine or local fiberglass store for details...fill a hypodermic with epoxy and start injecting from outside holes towards the center watching for flow from the holes closest to injection hole...like oiling your lower outboard gearcase from bottom while looking for fill from top...put a piece of tape on bottom of centre hole so nothing drips inside...let sit a few seconds...get an acetone soaked rag...push against the soft spot and quickly wipe away excess...lay down some waxed paper...stick in the threaded rod...then the sponge...then the aluminum or ply...washer and nut...same inside and tighten up...sponge to fair out clamping pressure...let set...release all...hopefully you have a dapple anti-slip pattern...easy to dribble gelcoat to match...put a dowel into center hole and finish gel same...on interior use a 'pop on' cover screw (plastic finish washer that recieves a coloured button) or perhaps a snap button if useable... Phew...I have a 3 inch area forward of my main hatch I just did this way, luckily on smooth white gel only... The trick is drying out the core as much as possible particularily if exposed to sun (ie: all topsides) before sealing in the moisture...other extreme options include hole sawing and removing punky core...but above should get you thru... Cheers... SH.
