Help with ptp please!

[froggerbass]

18’ X60, 115 Yamaha 4 stroke Yamaha 21-k prop. Bought it with no jack plate 5.75” ptp. At 4500 rpm it ran 41 mph. If you keep trimming up you get To 5400 but gain no speed. Rooster tails coming off the side right in front of the console. Seems like it never fully gets up on pad. Added a jack plate, raised it up to 4.25 ptp. Now at 4500 you get 37 mph and trimming it up to 5400 rpm gains no speed. The hydrofoil is at the surface at 5400. Still rooster tails at the console. I’m lost on this. Please, any advice would be appreciated.thx

[alli ss]

You got a lot of weight in the front? Sounds like you need a prop with some more bite to carry the bow a bit better

[froggerbass]

Any suggestions on a prop to try? And would that be enough to get it up back to where it was and up to be it appears it should be - around 45 mph. No on the weight. No
tackle, no rods. Nothing on the front deck.

[HOOKWETTER]

Trophy’s always ran good on these hulls. Look around for a used one in a 19-21 pitch worth a shot.

[alli ss]

Bravo or tempest would be my bet

[21XDC]

Bravo or tempest would be my bet

How would you fit a 4 3/4 in big barrel prop on a 4 1/4 in small gearcase 115?

[1Holeshot]

How would you fit a 4 3/4 in big barrel prop on a 4 1/4 in small gearcase 115?

My toughts exactly. Hub and prop diameter both too large.

[froggerbass]

I was wondering that myself. Yamaha recommends 13.25 or 13.125 by 20 or 21. But not sure if those props would help me.

[alli ss]

How would you fit a 4 3/4 in big barrel prop on a 4 1/4 in small gearcase 115?

Yea you got me there! Too many threads about needing props got me mixed up

[Arkyarcher]

Check the pad(no hooks or dents close to transom), check that you are getting full throttle, and your tachometer is accurate. If all that's good then start trying props. At least that's what I had to do.

[froggerbass]

That process makes sense. I’d really like to know how I’ve lost speed by adding a jack plate and raising the PtP 1.5” though.

[Arkyarcher]

My first thought would be that it depends on the jack plate added if the cables were changed or hooked back up the same. Also if the pad does have a hook at the transom it would come into play more with the balance point moved aft.

[froggerbass]

The cables were changed. Had to get a steering cable a foot longer and a throttle cable three feet longer in order to install the hot foot.

[froggerbass]

http://pic20.picturetrail.com/VOL132.../414467344.jpg

http://pic20.picturetrail.com/VOL132.../414467551.jpg

http://pic20.picturetrail.com/VOL132.../414467552.jpg

[Arkyarcher]

That section looks good , how about the rest.

[froggerbass]

No hooks, no dents. Raised it up to 3.5” ptp. Seemed worse. Wot got 26 mph at 4000 rpm. Trimmed it up to 5500 and again got to 37 mph. Kept trimming after until the nose started bouncing up and down and did not gain any rpm or speed.

[froggerbass]

With so much spray coming off the sides so far in front of the console it really seems like it’s just not getting up on pad, but I’m not sure where to go from here

[Arkyarcher]

Maybe a smaller pitch prop with more cup. What's max hp on the X60

[21XDC]

Take the foil off and lower the motor back down. Test again. These smaller diameter props can not run at motor heights of v-6 props. And the foil is tons of drag at lower heights.

[froggerbass]

Interesting. That makes it sound like the original set up was best at 5.75” ptp, no jack plate, top speed of 41 with the boat not getting fully on pad though. Could I get some clarification on why that’s the direction I want to head?