3 blade or 4

[Genie Aye]

You will loose RPM for sure by staying the same on dia and pitch. The question is how it will pull out of the hole??

You will have to let us know---theory is it will pull out better, but if it is to much load--you know what will happen--

This is the prop change question we all have for sure.

[smokeonthewater]

I borrowed the following from another forum I frequent:

"ESSENTIAL DATA REQUIRED
When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions.
1) Performance issue you are trying to correct.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
5) Engine/drive make, model, year, and HP
6) Boat make model, year, length and weight"

(posted by JB on Iboats.com)

With this data we can figure you prop quite accurately.

[steplift20]

response to most questions.
1) Performance issue you are trying to correct.--- get on plane faster and lower rpms to with in range 5800
2) Current prop manufacturer, model, aluminum or stainless as a minimum.--- aluminum, 13x19 its the prop that came with the engine
3) Current prop diameter and pitch (required)---. 13x19
4) Wide open throttle RPM and speed with an average load (very helpful) ---6400 rpms
5) Engine/drive make, model, year, and HP--- yamaha 4 stroke 2003 115hp OB
6) Boat make model, year, length and weight"--- 19 foot polar 2003 about 2000lbs center console

[smokeonthewater]

Got the fellas on iboats workin on it... I have a couple ideas but waiting to see what they think.

[smokeonthewater]

are you certain that your tach is correct? I have been running some prop calculators and am coming up with a lot lower pitch than you have now.
what is your current top speed?

any chance that your hub is slipping or that your prop is ventilating?

Such a high wot rpm should go hand and hand with a dynamite holeshot.

[randlemanboater]

Originally Posted by smokeonthewater

Such a high wot rpm should go hand and hand with a dynamite holeshot.

That has been my experience as well...if your prop turns too many rpms at wot then your holeshot should be neck snapping.

[smokeonthewater]

first reply on iboats
Unless I missed it I didn't see a wot speed.A brief check of Yamaha performance bulletins
a 20 ft11" Polar Craft CC with a 115 using a 13 X 19 al prop 2500 lbs ran 38 mph @ 5850
0-20 5.25 seconds. (antiventilation) Plate is 1/4" above the bottom It seems his setup is right though perhaps check the height.
Does he trim down for hole shot?

soooo yeah what is the motor height and top speed is gonna be an important key in solving this issue.

[smokeonthewater]

whoops... double post