[jclark003]

I doubt the addition of a RIB will force you into new props. tiara does a good job of specing props so that the engines are able to achieve manufacturers rated WOT rpm (plus a couple percent) at max weight. 600 pounds is about the equivalent of carrying an extra 80 gallons of fuel which isn't much for a boat that size. If you tend to run with a lot of gear/fuel/passengers on board you may need to tune the props a little.