Ah, yeas the classic Joker story from the 1970s... oh, wait, no. Completely different story.

Of course, the whole myth of piranha being voracious eating machines that can strip meat from a cow in a few seconds is a myth created by trapping and starving a group of piranha for a few days.

"We all knew Ollie wasn't going to make it."

Ollie could have been used as part of the hull to provide extra buoyancy.

This the movie with Lee Majors in it?

Yep. And Karen Black.

Majors also starred in the KTMA-era movie The Last Chase.

I've seen this movie, but for some reason they called it Treasure Of The Piranha.