How far can a prop be changed?
 

On my recent trip to Fla I ran my boat in it's Normally aspirated form instead of blown (272 Baja). 1.50 ratio drive gears,540 that peaked at 5600 N/A. I took two props with me,a std 28 bravo one that was cut down to a 27 1/2 by hydromotive years ago and my labbed 26 pitch bravo that B-blades added their Baja cup to last year. I took the cutdown 28 because it is the most useless prop in my collection. A year and half ago boat ran 74 mph with std 26 bravo ,76 mph w/labbed bravo 26 pitch running real light in fall air. I had the labbed 26 tweaked w/baja cup and boat ran 74 mph afterwards,weather conditions might not have been identical though to the first time,was windy and choppy.
Fast forward to this year,down in Fla I ran the 28/27 1/2,boat was loaded to the max with a bunch of crap my sister decided she couldn't go boating without,including her kids and husband on top of enough clothes and food to make it a week in case we got stuck on the intercoastal:rolleyes:. Boat would turn 4900-5000 and run 68-69 mph on gps speedo. Thanks to the excellent navigating skills of My beloved brother-inlaw I got to drive acrossed a shell bed when pulling into the boat launch. I ran my labbed 26 the rest of the time,it would pull 5000-5200 and about 70mph,I saw 72 mph a couple times but couldn't get it there most of the time ( with same boat load of "stuff").
Now I have this 28/27 1/2 prop laying around that has about 1/8" of edges chewed up and a blade or 2 that are visually tweaked. Other than tossing it in the garbage could it be re-pitched,cut down more,labbed/repaired to try to get boat to run in the 5600 rpm range when loaded down? Or is going from a 28 pitch to what I would guess to be about a 25 or 24 pitch just asking too much? it's interesting because it's junk anyways,if I had it tweaked and it ran the same speed but didn't lug the motor diown so hard I would be o/k with that,if it turned up the rpm's AND actually picked up the loaded down speed I would be estatic,food for thought,Smitty

We normally only like to adjust up or down 1 inch of pitch although we can use cup reductions to gain more rpm.

Diamater reductions can also be affective. Especially in low X dimention set ups.

We would need to see the prop to determinw the best move per its damage.

Brett