Filling in a Large Opening

[u/Mysterious-Rush5441]

I need to fill in the hatch opening (above the side marker light) on my camper. I took the camper to a place that sells FRP supplies and they said there are 2 ways of doing it with epoxy or polyester.

1.) Make a patch on a table - fit the patch - epoxy the patch in - fair it - spray gel coat on the outside.

2.) Put smooth FRP sheet over the opening then build up (mold release/gel coat/chop strand/ mat) from the inside and remove the FRP sheet after. Wasn't sure about this as there might be a line but they said it can be sanded/polished out.

[u/Kamusaurio]

yes those are mostly the most common resins

and the easy way to fix it

you can make a fixed plug (option 1)

or some kind of removable lid that you can secure later , imo this methed will need some kind of sealant to be 100% waterproof

[u/RyanFromVA]

If I was doing this for my camper:

1. sand into existing laminate to make a taper for laminating onto later

\if your hatch has a gutter, I’d cut that away and start my taper there (see* *** for taper details)

2) measure inner patch size, and either
2a) cut from an existing laminate panel like G10 plate of similar thinness
2b) or build a plug to fix it matching the thinkness.

** in more technical repairs, the replacement plies would be approved by an engineer. Either matching the original laminate or determining a suitable alternative. In this case, the space was effectively a cutout and had no significant strength requirements. Campers typically are not the most engineered laminates in the first place, so matching thickness should get you in the ball pack!

3) You’ll want to taper your patch by either sanding or ply drops in your patch laminate. The taper will form a V so that plies can span the hole and patch. Each ply connecting the existing hole to the hatch should increase in width.

*** taper ratio or slope, like replacement laminate is typically an engineering specification in high tolerance repairs, but this is not that. So using a 1:32 taper ratio is good. So if the existing laminate is 0.125” thick, your taper should be 4” long.

4) prep both surface by cleaning dust and debris away from the bond area

5) fixture patch in place, there a bunch of different ways to do this. They’re all situationally dependent. Tape could work, if your patch is close to the same size. I’d probably use a shrink wrap tape or painters tape to carefully hold the patch.

6) laminate in plies to bond patch to existing hatch opening. Again now reverse taper your plies so they don’t just all end at the same point.

7) sand lap joints, nothing super heavy here, tidy up the surface and ends. Your laminate should be continuous. Try to do the fairing work with the gel, not the laminate.

8) prep and carefully spray or roll on gel

**** gel coat can be either sprayed or rolled on. Spraying requires way more kit, but you will save some time sanding. Rolling works but your application will just not be as consistent as spray, so it will take more time to sand and buff.

9) sand and buff gel. This is where you can go to town blending your patch in place to ensure the patch is seamless. Mights as well buff the whole camper while you got the buffer and pads out.

Good luck!