The blowout was a long the center seam, then into the seat fabric.

I used polyester sewing thread and backed the mended area with a piece of a knit shirt. The shorts are somewhat stretchy. I tired of hand sewing and used a sewing machine for the horizontal stitches. On first wear, Spouse popped some of those stitches. Spouse wears the shorts to work in a school IT office and to golf. Most of the repair is holding firm.

It was a learning experience. Probably the machine stitches would have lasted longer if a zigzag or other stretch stitch was used.