RPM questions

[mike350]

I bought a new to me, boat and took it out for it's first run yesterday. It's a 1992 Campion Allante 170 - weight?

1990 Yamaha ETD 115
WOT 4900
speed 43 mph
S/S prop 13 x 21-K

The engine is rated for 4500 - 5500 WOT
The boat works extremely well. On plane in seconds, no lift and I am very happy with it.

Will I pick up speed by going to a different pitched prop to get to 5500 WOT? Or should I just be happy with what I have?

GPS battery died before I did this test and the speed is off the speedo. Playing with the trim, I would hit 4700 rpm -wot -and very fine tuning with the trim in waves, finally got to 4900 rpm - wot. I have a spare aluminum prop that I haven't tried. It's 12 and 5/8 x 13 k. I don't know the make of the props, there is no name. I am wondering what the K stands for??

Thanks
Mike

 

[mike350]

Re: RPM questions

btw those figures were with 3 adults 2 kids and all my gear that will always be on the boat

thanks mike

 

[QC]

Re: RPM questions

Well . . . interestingly enough most test data shows that propellers spec'd toward the bottom of the range are faster top speed. It's even evident with Walleyhed's data ^^^^^

If you are running 21 inches of pitch now, that 13 inch prop is really nothing more than an emergency get home deal. If you were struggling to get her on plane, I might suggest a 19, but I can't ever see a 13 as right unless you were running her on a lake at the top of Everest . . .

 

[mike350]

Re: RPM questions

sorry 12 5/8x21 aluminium