how many layers of cloth?

[goransons]

I'm still working slowly on repairing the black tank the PO chopped up. This is the corner tank on the 63 safari. Unlike most tanks this one sits on top of the floor and the toilet bolts directly to the tank.

The PO drilled holes outside the toilet because the bolts were rusted and took the top of the tank out. The tank itself is about 1/4" thick. The first step I did was to clean and aggressively sand with a grinder the area to be fiberglassed. I built a small form to create a smooth surface and poured in a little epoxy resin, then started putting in layers of cloth to fill the actual hole, once I reached that thickness I started a few layers across the inside of the tank from below gradually getting wider until I've met up with the cross braces inside the tank, a total of about 14" wide. I need to sand the surface to continue since it has cured (I had a couple weeks of business to attend to). Since the toilet sits on top of this, and a person on top of that, I could see easily approaching 350 lbs on top of the tank.

The next layers I want to install will be the entire top area of the tank, then down the sides and onto the bottom of the tank. This should help transfer the load down the sides of the tank and to the bottom, not just to the underside of the lid of the tank.

How many layers should I do to attain this? I started to add some aluminum stock to stiffen the lid from underneith but decided this was likely to fail due to flexing, so I took it out. I'd rather go too much than too little but have no idea what I should even guess with. I don't want to get this all in, be in the thinking position at the camp ground and take a rapid decent down into poo town....



Any suggestions?