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I was forced to put on a new prop, - went with a tad larger so i could save $200 --- now and I have 1/4" to an 1/8" clearance from my prop blade to my skeg anode, its that ok?
cant imagine it would cause any issues - but just checking --
Yamaha F150 4 stroke ---
previous 14 1/4 x 20
new 14 3/4 x 20
from my reading it said in increase in 1 inch in diameter should result in a decrease in 100-200 RPMS. The stock prop was already at the top end of RPMs recc. on the motor. ...
I went up 1/2 inch. What will the "not good" difference be?
Run the boat in calm water at 500 rpm increments and note the speed on a GPS (speedometers aren't that accurate) from idle to wide open throttle. Don't use the trim tabs during the test. That's what we do when testing boat performance for the magazines.
Props are one of the biggest performance variables and every boat is different. If you still get a good hole shot, the rpm limit is within the engine tolerance (it's always better to have a reserve rather than push to the max) and the blades don't nick the anode, you should be fine.
silverking wrote:Run the boat in calm water at 500 rpm increments and note the speed on a GPS (speedometers aren't that accurate) from idle to wide open throttle. Don't use the trim tabs during the test. That's what we do when testing boat performance for the magazines.
Props are one of the biggest performance variables and every boat is different. If you still get a good hole shot, the rpm limit is within the engine tolerance (it's always better to have a reserve rather than push to the max) and the blades don't nick the anode, you should be fine.
Yep will do thanks---
As far as the 500RPM drop.. I got to researching some more, it was worrying me... based on Yamaha's tech papers and call to Yammy tech, I should see a drop of 50-200RPM max (closer to lower end) - so I feel better bout that---- either way I own it so it aint going no where--- except prop shop to get dings out after this weekend-----
Well -i think it is was a pretty even swap - loaded down with 2 more guys than normal, 3 coolers of ice and dive gear, we had same top end speed - 42-44mph. out of the hole was a little less get up and go, but like I said, 2 more guys than I'm used to. Ran great, RPS,not sure, my tach came unplugged at some point, and i didn't mess with it. Im happy---
- went with a tad larger so i could save $200 --- now and I have 1/4" to an 1/8" clearance from my prop blade to my skeg anode, its that ok? 
