I seem to have a knack for destroying my black tank

I have successfully patched a black tank with pvc/cpvc/abs glue and fiberglass spackling tape. Clean the surface and then use successive applications of glue and fiberglass tape, overlapping the tape and spreading the area as needed to make a secure patch. I've done this kind of patch and it seems to hold well. Another patch I've heard people use is Eternabond roof tape although it might be better suited to a small crack than a large gash. I also like Old Biscuit's method.
Russ