just picked up a 98 w/280hrs. took out for a romp @ lake erie. 3 adults full tank of gas best it ran was 60 on gps. I think it has bravo 1 w/28P props. what am I doing wrong? shouldn't I get low 70's?

A local guy had that same boat (might have been a 99). He once said he was told 72 when he bought the boat but never saw more than 68. Seems it should hit 70, and I believe 28's are the right prop for the boat...maybe those props need some work?