My parent's bought an 18' Riviera jet boat new in 1972.
I doin't have a pic handy, but it was a splashed copy of the 18' Sea Ray. Lot's of freeboard, windshield and fold down back to back lounge type seats.
It was built in Oregon and had a 455 Olds with a Berkeley 'E' pump. It ran and handled well, top speed was close to 60 MPH by speedo.