Prop Issues

[gotopless]

I have searched high & low on this forum and have read good info, but I'm looking for more.....

I have a soon-to-be but not-so-classic-yet 2003 20' MA w/ a coffin box & t-top. I grew up fishing in my dad's 1973 20' so maybe that will let me in the club. My current boat came with a Honda 130 4-stroke that was AWEFUL. I repowered with a 150 etec. Love the boat and motor but am having trouble finding the right prop combination. I have been running a 15 ¾ x 17” Rebel and tested a 14 ¾ x 19” Viper this weekend. The Rebel tops out at 39mph & 5000 rpm. The Viper hit 42mph but only 4600 rpm. Not sure what to do next…will probably try a 17” Viper. Here is all speeds & rpm's. Manufacturer lists full throttle rpm as 4850-5850 and peak HP at 5350 rpms. I am looking for a decent holeshot (for skiing & wakeboarding) and good cruise speed. I'm least concerned about top end although I would love to break 42 mph. Please offer suggetions. thanks


RPM********* Rebel MPH******* Viper MPH

3000******** 22********* 23.3

3500******** 27********* 30.7

4000******** 31.8******** 36.2

4500******** 35.5********* 42

5000******** 39.8********* WOT was 4600

[Bushwacker]

Will send you a pm tomorrow with a spreadsheet of rpm/mph/gph/mpg from 4 different props I've tested. That 150 E-Tec is really about 165! I've seen almost 50 mph on my Seafari; don't know how much the bracket is worth but I'd think you should get mid 40's with a light load. Make sure motor is not mounted too low; should be able to run with cavitation plate about an inch above bottom if running a cupped prop.

[Briguy]

Go,

I agree. My motors are mounted with the cavitation plates about 2" above the bottom of the hull. Are you trimming the motor out at wide open?