I have a '69 15' Glastron tri-hull bowrider which had a 65hp Mercury outboard with a 12" x 15p prop and went 30mph (by GPS) with 4 adults. I'm replacing the 65 hp with a '78 80hp Mercury outboard which was on a pontoon boat with a 14.5" x 12p prop (clearly no good for my boat). I'm also installing a tach, but I need to buy a prop just to get started so I can use my tach. Any ideas on a good starting prop? I use the boat mostly for lake cruising, fishing (no trolling), and some skiing. Thanks for any input.
