If going from a 3 blade 10"pitch to a 4 blade…do I drop down to an 8 pitch or go up to a 12 pitch? Not even sure they make an 8. Confused…please help. 
What kind of motor is it. Typically your RPMs will drop due to the extra blade therefore more drag. Is there a reason to switch to a 4 blade? 4 blades due provide better hole shot and slow speed performance and less vibration. They also on average run 300-500 rpm lower for the same pitch depending on the motor. So yes you should drop down in pitch.
Thanks, need more torque and running a micro jacker
I HAVE SPENT MOST OF MY LIFE FISHING AND WASTED THE REST OF IT!
Yamaha 25 hp 4 stroke. o you think a 9 pitch would be ok?
I HAVE SPENT MOST OF MY LIFE FISHING AND WASTED THE REST OF IT!
Yea that pitch would work but your gonna loss top speed
Do you have a stock aluminum prop now or a good cupped stainless?
Capt. Larry Teuton
Swamp Worshiper
aluminum and a composite 3 blade, neither has the torque i need. I use this boat in really shallow water in a lot of weedy and muddy spots.
I HAVE SPENT MOST OF MY LIFE FISHING AND WASTED THE REST OF IT!
Does your boat have a tachometer?
Capt. Larry Teuton
Swamp Worshiper
Fraid not. I really don’t have many choices with dropping down. I am having a hard time finding a 9 pitch unless I want to buy SS.
I HAVE SPENT MOST OF MY LIFE FISHING AND WASTED THE REST OF IT!
where are you located? You could try skips prop shop. Off cross county Road. He’ll let you try couple different props.
Thanks, I may just stop by there this week.
I HAVE SPENT MOST OF MY LIFE FISHING AND WASTED THE REST OF IT!
Not sure if they have it but Overton’s.com Solas props 4-blade.
Fishing the beaches, Bays & Ocean of Wildwood/Cape May, NJ
Soon a resident of Georgetown, SC
You really need a tachometer to get the right prop. I’m not sure a Yami 25 can efficiently spin a 4 blade. If I were you I’d replace the 3 blade aluminum with a 3 blade cupped stainless. It is much more efficient. And get a tach. You need to know your rpms. You can get little inexpensive units that connect to a plug wire. See http://www.tinytach.com/gasoline.php
Capt. Larry Teuton
Swamp Worshiper
4 blade 9" pitch works like a charm
I HAVE SPENT MOST OF MY LIFE FISHING AND WASTED THE REST OF IT!