You don't say where the hole is, I can't make the link in your second post open.
Here are some photos of the inside of an early model 5.2. The tubes are just cardboard, soaked in resin & a layer of glass. They serve to stiffen the large areas.
http://www.thebeachcats.c…ictures/?g2_itemId=82844
Here is a link to how I patched a hole that had no access from the inside. Your damage is bigger, but can be fixed the same way.
http://www.thebeachcats.c…ictures/?g2_itemId=77105
I would remove the hull, so it can be laid on it's side as needed.
If the area on the right of the photo in your initial post is the keel, fix that first, lay 1/2 dozen layers, or more right along the keel, & extend them up the side a couple of inches. That will give solid keel, & side, along with making the hole smaller. Now you will just have a relatively flat area to work with.
Are those tubes also on the side where your damage is?
If so, you will want to replace them with some sort of similiar stiffening device, easy to do.
Once you solidify the keel, place hull on sawhorses with damage facing down, cut a sheet from some material that is sort of flexible,(a juice jug may not give you a large enough piece) make it several inches larger than the hole. Lay up 3/4 layers of matting on top of your flexible backing,(juice jug or whatever)& wet out, use the least resin you can & still fully wet the matt. Have the nylon strings attached to the backing. Let the patch set up, but not to the point of hard curing, you want it to be flexible still. If the adjacent hull has stiffening tubes, add them to the top of this inside patch,(you can pre make them from carboard tubes wetted & wrapped in matting) let them extend past the patch. Using a brush or gloved fingers, generously smear some resin,(you can thicken this some with additive so it doeasn't run) over the inside of the hull, covering the area the patch & added stiffener tubes will sit on. Now fold your still flexible patch, sort of like a taco shell,(fold as little as possible) just enough to get it inside the hull. Place it, then use the strings to apply enough tension to pull it against the hull. With the hull on its side, patch down, gravity will assist in pulling the resin into the proper place.
Using any suitable scraper, gently remove excess resin on the outside, this will make it easier to add layers from the outside, without excessive build up.
Let this cure, then flip the hull so patch is up. Now grind around the edge of the patch, working to remove gelcote for 1-2" from the edge. Very gently bevel this area, don't cut into your inside patch. Now add 2-4 layers of matt from the outside. You want max matting, with just enough resin to wet the fabric. Easiest way to do this is paint the area with only 1mm of resin, lay dry matt on, then gently draw the brush across matt, from center out, without adding resin to the brush. Don't try to get it all with the brush, use your fingers to "tap" the matting into the resin, it will wet out, with no additional resin needed.
Add several more layers this way, you will be able to clearly see the fibres of the matting, yet it will be fully wetted. This is strong, but doesn't add much thickness. You can go 3 layers,without excess heat building, then let it cure.
After the final layer, use a random orbit sander to gently smooth out the inevitable "points". Finally paint a very thin layer on to, to seal any fabric that was exposed by sanding.
The patch will show up, easiest to just use some appropriate white paint to cover it up, if you want to gel cote, that's another challenge, bigger than the actual fix.
Think this all through, you will need to be organized, once you wet cloth is not the time to remember you need strings attached, or more fabric cut. Contrary to some opinions, the patch will be stiffer than the original hull, though thicker.
Do I need to say it again, organize & dry run in your mind how everything will go together is the most important thing, & prep. The actual fix,(other than full cure) is a 1 day job.
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