I've had good luck with aquaseal. Sand lightly, clean well (I would probably use acetone),
And put a thick fillet around the fill neck. Be sure to let the glue set over night before use.

Tom Ladd

Repair method that works like a charm for me. Clean repair area on both sides with alcohol. Use masking tape to align and hold edges of ripped area together. Flip over and use sail repair tape (polyester ripstop tape, comes in two inch roles in several colors) cut in half, one inch wide, to run leng...