Gas tank hatch repair

That's right,a waffle or doughnut if you like.It works like a truss in a roof. If your handy with a table saw you can 45* the outside edges and score the bottom side every 3-4 inches at 1/8 deep to make sure the plywood bonds to the mat on underside and weigh it down on a flat surface with some downrigger weights.It should be stronger than original when done.
 
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got busy last night, gave the plywood a coat of resin on both sides,
laid up one CSM on the underside of the hatch, and let it cure for a few hours.
made up some PB and glued the plywood to the hatch,
then added 200lbs of downrigger balls, scuba tanks, paint cans and lead bars and let it cure over night




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made some more Peanut butter resin and chamfered the edge of the ply, quickly followed by two additional layers of CSM, wetted out and rolled.... its tough to get the edges just right, and other than one airbubble that formed from a knot-hole its looking good and curing downstairs


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That should do the job.Give it a light sand,wipe w/acetone and give it a coat of gelcoat to seal it.Don't forget to add airdry to gelcoat.I don't know how you get away with doing that in the basement,it must stink up the whole house.Doing it in my attached garage was bad enough,you know what an unhappy wife leads to.:);):(
 
I'm in the process of doing mine also. I took all the saturated wood out ground it down to clean glass then layed down a layer of 1708 biaxial mat then laminated a piece of 1/2" plywood as the is what was there previous to the mat with epoxy (West System) and some 403 adhesive filler then weighted it down with batteries and lots of lead. I built a nice flat surface to keep everything nice and flat. I beveled my plywood's edges to 45 degrees to help the mat lay better and put down a couple layers of 3" strips of 1708 around the edges.
 
ive had a fan blowing out the workshop window for the past 4 days, lol..... yes the whole house stunk, but even though i was wearing a respirator i couldnt smell it, girlfriend could when she got home!

what is airdry for the gel coat? all the resin was waxless, do i still have to sand and acetone?
 
looks good nerka, about the same as i did but with chopstrand matt and 3/4". good point about the flat surface. my new hatch is about 1/4" out from corner to corner.... it flexes just enough that it will still screw down flat though, guess the table i was using flexed under 200lbs of lead and scuba
 
Your cover is quite a bit wider so probably a good call on 3/4". It was my first time using the West system epoxy and it is pretty pricy but the lack of fumes and the precise measuring makes it so much more enjoyable to work with.
 
Airdry is essentially liquid wax that will rise to the surface of the gelcoat and make it so it's not sticky when cured.You don't have to sand if resin is waxless but there is usually a bit of a rough surface to deal with,not very important on a gas tank hatch that will hardly ever be lifted.
 
I didn't know epoxy was fumeless good to know when working in the basement

My materials were $101 for the fiberglass stuff (gal of resin, MEK, 3yards of CSM some interfibro stuff to make peanut butter with) and 41 for a sheet of ply. How does that compact to epoxy?

I think I still have a pint of gel coat , hope there's enough leftover


Thanks for all the advise guys!
 
A waxed gel coat or resin coat is the final step. Airdry is added to unwaxed resin or gel coat as a final layer. I find the airdry usually needs to be warmed up slightly before adding it to the gel coat to melt the wax. As Rayvon said, the wax migrates to the surface and creates an air barrier. Without this air barrier the resin will not fully cure/harden. There is also a spray on air barrier the name escapes me right now. Without this "waxed" layer on top the layup will be susceptible to chemicals, acetone will soften it very quickly. It allows the whole layup to cure properly.
 
You can spray PVA over inhibited resin to get it to fully cure, then peel it off and or wash it off with water. PVA is also used as a mold release.
Epoxy is the friendly devil, it is so much nicer to work with and then BAM you are allergic to it and it's fumes.
 
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