Fuel Tank Hatch repair

[RidgeRunner]

Because my hatches were very thin after removing the rot and grinding
I used 2 layers of 1.5oz mat wet out real good with polyester resin then placed composite down and weighted the dry side down with builders blocks, batteries and such. Drilled holes in the composite about every 4" beforehand to allow air to escape. Let it kick, sanded the resin around the edges and that which poked up thru the holes and glassed the backside. Gorilla strong.
I am not fluent with epoxy. So don't use my comment as "the word" but
If you are using epoxy with thickening agents, I would think you would still want it thin enough to put on with a roller and let it flow out flat. If it is thick enough to trowel on you would have more hills and valleys creating voids causing you to put more force on the wood coring to get the air out. If on the other hand you were doing a vertical transom and were using transom clamps I would say go ahead and make it thick, trowel it on, clamp the coring down good and tight until the paste is oozing out from behind the coring and wipe off the excess to save time later.
Someone will chime in and rip me a new one but this is my logic for what its worth.
See BenFishin already did. Mayo or Miracle Whip? My thinking was that air bubbles move more easily thru unthickened epoxy than mayo or peanut butter

[nymack66]

I will personally recommend a flow consistency like honey, you are basically looking for penetration and filling voids on a flat surface with a backing skin, Mayo will be better for a vertical fill or a lay up that dictates a thicker flow.
If you are using Epoxy be sure to use the correct thicken agent.
I personally did not use a thickening agent with my poly resin when I did mine, I wanted the flow and fill to be 100 % this just my 2 cents . Ridge is correct be sure to drill those holes..

[RWilson2526]

thanks for everyones input.... I guess I settled on a Honey mustard consistancy . Just thickenied it up a little....still flowed pretty good I guess.....drilling the holes in the composite was the first time I'd seen that so I drilled some 1/4" or so holes every 6" or so.....actually had a fair amount of resin squeeze up through the holes which i had to grind off this morning....

just put the glass and resin on the outside....definitely glad it wont be a visible surface as I'm sure it wont be perfect but it will be fine.... I guess what I gathered from all the different ways people have done this is that at least for this kind of repair its a pretty forgiving procedure....slap the crap on there , clamp it...done. the resin does all the work. Glad some of the mystique is gone from fiberglassing now that I have my first project under my belt....

BTW ...bailed on replacing the fuel tank.....the foam around that tank is bone dry and all looks good...I can just hear myself this season "ever since I replaced that tank i've had this problem and that problem"....if it aint broke dont fix it and at this point I'm not looking for more work. someday when it goes I'll be ready to do it. but for now the hell with it.

[bsteckel]

sounds like you nailed it!!!!

good call on the gas tank ... i hope i am as lucky :)

[RidgeRunner]

Excellent. Nothing like jumping right in and gettin it done.. If the holes had epoxy running up thru, you got it right without a doubt. Good job.

[bradford]

Sounds good, been needing to do mine for the last 7 or 8 years.

[reelapeelin]

Originally Posted by RidgeRunner

Because my hatches were very thin after removing the rot and grinding
I used 2 layers of 1.5oz mat wet out real good with polyester resin then placed composite down and weighted the dry side down with builders blocks, batteries and such. Drilled holes in the composite about every 4" beforehand to allow air to escape. Let it kick, sanded the resin around the edges and that which poked up thru the holes and glassed the backside. Gorilla strong.
I am not fluent with epoxy. So don't use my comment as "the word" but
If you are using epoxy with thickening agents, I would think you would still want it thin enough to put on with a roller and let it flow out flat. If it is thick enough to trowel on you would have more hills and valleys creating voids causing you to put more force on the wood coring to get the air out. If on the other hand you were doing a vertical transom and were using transom clamps I would say go ahead and make it thick, trowel it on, clamp the coring down good and tight until the paste is oozing out from behind the coring and wipe off the excess to save time later.
Someone will chime in and rip me a new one but this is my logic for what its worth.
See BenFishin already did. Mayo or Miracle Whip? My thinking was that air bubbles move more easily thru unthickened epoxy than mayo or peanut butter

Now I see why you have no fear of "Swiss Cheese"...

Hey Rob...gotta pull the tank hatch on the 21...the lid itself feels solid, but need to see what's goin' on under there...any words of wisdom on gettin that puppy off?...

[RWilson2526]

Originally Posted by reelapeelin

Hey Rob...gotta pull the tank hatch on the 21...the lid itself feels solid, but need to see what's goin' on under there...any words of wisdom on gettin that puppy off?...

Mine came up pretty easy....there was a nice caulk job in the seam between the hatch and the floor but fortunately there was no bead on the flat lip of the floor under the hatch ....so just cut around the perimeter with a razor knife, took out the 6" round access plates, grabbed a hold and pulled. Came right up.

[racrx7]

drilling the holes in the composite

I will we doing this same repair as soon as it warms up some. When you say "composite" exactly what material did you use to recore it with? I was under the impression just good plywood would work? Also what thickness of composite or plywood should I use for this repair?
Thanks

[RidgeRunner]

Originally Posted by racrx7

I will we doing this same repair as soon as it warms up some. When you say "composite" exactly what material did you use to recore it with? I was under the impression just good plywood would work? Also what thickness of composite or plywood should I use for this repair?
Thanks

http://www.coosacomposites.com/nautical.html

There are different products out there but plywood is what the factory used, on mine they laid out small blocks of 1/2" plywood and glassed them in with the chopper gun. I rebuilt using Coosa but now I am not sure about density. Cost a bunch but glasses easily. I am almost immune to the itch but I can look at a sheet of Coosa and start to itch. http://www.coosacomposites.com/nautical.html
Plywood will work just fine, I recommend 5/8" or 3/4" ACX or BCX FIR on the low end and Marine Tech brite or pressure treated and Kiln Dried After Treatment (KDAT) on the high end. Some say not to use pt because of bonding issues. All these plywoods have such a smooth finish you need to rough them up a little to aid in adhesion IMO, essential if using pt. as it has a tendency to be case hardened after drying. Marine Tech has fewer voids in the interior plys and is better but only by a small margin.
I stock and sell Marine Tech in 3/4 PT KDAT and I have a pontoon boat builder that eats it up. He glasses the topside with good success.

Reel, you like the swiss cheese, LMAO. I filled every hole on my 20cc rebuild. I was shocked at how many holes I had to make in that baby for all the rigging. Wore out a roto-zip and challenged more than one hole saw. Your 74 model looks like swiss cheese but not for long. I'll have it looking like Havarty in no time. Pass the mayo.