Originally Posted by falcon0310
in your garage ? i have rib that built in 3 sections and removal tubs i cant spell !
i did like my quicksilver 3.80 but everone sweares about bombard a380
factors affecting speed
mass in boat
mass of boat
mass of engine (2 stroke lighter 4 stroke)
engiine power ( if you have 15hp is it putting out 15hp ie tuning)
Prop condition/size pitch
trim of engine
rigid hulls shape shallow v deep v
so if you go from a sib to a rib you will double your boat weight.
I think your easiest cheapest solution is check your prop/pressure of boat.
youll need a tiny tach ( or similar easy cheap to set up,see you tube) check manual for boat/prop for pressure and working rev range of engine.
pump up boat to correct if not already
engine with tiny tach fitted go out in boat on your own if you have correct prop you should be 200rpm under max at wot (wide open throttle) (my engine range is 4500 to 5500 rpm so with correct prop i should be 5300 rpm with me in alone)
if not change prop pitch ( each change of pitch = 150 to 200 rpm
so going from a 12 pitch to a 11= reduce by 150/200 rpm
going from 12 to 13 = increase 150/200rpm.
if you have the wrong prop this will have a big affect on speed
i have a 4m rib with a 30hp two stroke top speed 28 mph
hope this helps!!