Originally Posted by codprawn
Just wondering if the 24" prop is going to be suitable - even empty the boat will have 500l of petrol on board. I suppose it's just a case of try it and see???
Congrats on the new arrival, before I forget.
19" to 24" is quite a change. General rule of thumb is 200 to 250 rpm for each inch of pitch change (down in pitch = up in rpm.)
What I found in my limited testing is that the rule of thumb is an extremely rough estimation. Mine went from 19" pitch (turning about 4000 rpm) to a 13" (which should have put it just over 6000rpm) and couldn't get a reading as it sat on the rev limiter at about 6100.
Ended up with a Ally 15", turning a tad over 6000 with just me and a less-than-full fuel tank.
Now running a SS 15" which turns about 5800 with a light load, about 5500 to 5600 with a "normal" load.
So, whether or not the prop will work for you depends on a lot of things, not the least of which is where the 19 falls in the rpm range. The 24 should put you somewhere around 1000 to 1500 rpm higher, in addition to less of a hole shot, and a substantial increase in top speed (assuming you don't lug the motor down.)