When the bottom of my bathtub was cracking I just used TAP's softest epoxy--and lots of it... Like there's about 3/4" covering the whole bottom of the tub. Then I topped that with a coat of marine non-slip material. It's been eight-years and the tub floor actss like it did origianlly--it flexes due to rotted flooring beneath it, but it hasn't sunk out of sight yet!! Look up the TAP website <http://www.tapplastics.com/shop/product.php?pid=27&> I might try rot doctor and then pour on a thick coat of their softest stuff. I'm looking for a stopgap measure--just so the coach stays road-worthy for a few more trips (there isn't actually any discernable sag yet). It only has to last as long as I do, and I'm on the proverbial slippery slope with a progressive neurological disease. Oh, and I'm considering cutting off the rear bumper extensions (the diamond pattern steel it supports has pretty much rusted out) and the spare tire carrier, which just adds weight to the rear where the trailer doesn't need it. I might get rid of the propane system, too, since I went to an electric-only fridge and don't use the stovetop or oven (the microwave does it all, and what it doesn't the microwave and a hot plate will). So I could cover the hole in the kitchen countertop where the stovetop was with cutting board to fit all the way from the rear kitchen sink to the closet wall (my 1960
24-footer is the single bed model with the vanity and two full length closets--one on each side.
Getting back to my main problem: 1) a previous owner cut off the belly pan from beneath the rear bath, leaving the floor to rot and the frame, outriggers, etc. to rust,, and 2) the dark water tank leaked for some time before I realized it, soaking and rotting the floor beneath it.I stripped the rotted layer and overlaid it with 3/4"plywood. Then I a direct fed the toilet through the existing hole in the floor (necessitating two 90 degree PVC fittings since the hole for the black water tank drain valve wasn't centered between the back-closet wall and the bathroom cabinet
/countertop. So now the toilet sits on a "throne" (a box covering the the convoluted PVC double 90 degree drop from the toilet to a four-way PVC fitting--4" in the top and out the bottom, and 3" in from each side (for the kitchen drain pipe and the bathroom drain pipe--coming from opposite directions)! . So this was OK, except that it dropped the sewer outlet so close to the ground so that at most RV parks the sewer hose goes uphill and the contents backs up into the fitting. I manage to seal up the whole thing, though, so that it doesn't leak onto the ground.
To my dismay, however, hot-humid air was inundating the back clothes closet. Upon investigation, the particle board floor screwed down insanely with no less than 26 1 1/2"screws was soaked through. And I can't get to it from underneath to see what's up since the belly pan still covers that area. But just past the rear end of the board I was able to punch all the way through the floor.
So when I get up enough courage, I'll pull off the particle board and probably trim the belly pan further forward so I can see where the water is coming from. This is going to entail jacking up the rear of the trailer, something I'm not looking forward to.
The good news is: when I put a level on the exterior of the trailer--horizontal frame member, bumbers, wraps, etc, it shows no sag. Inside is a different matter, however. It's definitely tilted to the left side.
The plan: lighten the trailer as much as possible, especially in the rear, rot doctor any wood I can get at, and then epoxy the begeezus out of it. Obviously, the closet floor will have to be replaced. Probably remove the propane lines and bottles and the Princess stovetop and oven. Cut the belly pan as far forward as necessary, leaving the curve intact and not getting into the U channel thing that I don't understand anyway. That way I could arttach an alternate material to the foot or so of belly pan curve left intact. There are lots of "outside the box" ideas that would work. Like an upside-down tonneau cover. Any ideas would be appreciated. Hopefully the frame and floor are still serviceable forward of at least the axle. One idea for inspection would be using light aircraft inspection holes and covers.
I know all of this will probably horrify the RivetMaster, but I know he understands my situation. I have to do it the "quick and dirty" way. And nobody knows everything, anyway. For instance, when I inquired why he was death on using any corrosion cleaner on the shell that contained acid: he must have been unaware that the active ingredient in the Alcoa step 1 cleaner sold by the Airstream Store is acetic acid.