Re-pitch your impeller thread

[Christian_83]

Hi Guys.
So i was thinking if it would be an idea to make a thread, were people could post there experience with re-pitching their own impeller, post pics before and after in a gauge, along with what difference it made in performance?
Seems like a subject that a lot of people wanna get into (with good reason) and not to much guidelines to

 

[Tyler Zane]

I'm in, and perfect timing. My jettlab gauges should be in soon. Time to get to tweaking.

 

[Jetfiend]

Hi Guys.
So i was thinking if it would be an idea to make a thread, were people could post there experience with re-pitching their own impeller, post pics before and after in a gauge, along with what difference it made in performance?
Seems like a subject that a lot of people wanna get into (with good reason) and not to much guidelines to

Good idea Christian! It would be great to see some different ideas on what people are using for a jig - I was thinking about building up a receiver hitch jig.

 

[Quinc]

First time today.
144mm 8/13 Solas concord

@DAG Jettlab gauges show it as 11/14 (11Leading and 14 trailer)

Going to try 10/13

 

[Quinc]

Ok so looked at it again. and the pitches overlap in the middle. So think I should only bend the green lines and not touch the pink middle part:

 

[DAG]

Ok so looked at it again. and the pitches overlap in the middle. So think think I should only bend the green lines and not touch the pink middle part:

Correct. About 2 inches from each end

 

[Big Kahuna]

Good idea Christian! It would be great to see some different ideas on what people are using for a jig - I was thinking about building up a receiver hitch jig.

Made this last week

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[Quinc]

Made this last week

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Why all the marks?

 

[Big Kahuna]

Why all the marks?

1" marks. To see if all blades are consistent.
Plus it looks cool when you stick your head underwater to see the blades spinning!
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[Quinc]

Correct. About 2 inches from each end

When measuring should the line be along the bottom of the blade or the top of the blade?

 

[DAG]

When measuring should the line be along the bottom of the blade or the top of the blade?

I like to mesure the bottom as the top has taper as the blade ends on all the impeller I've pitched so far.

 

[Sanoman]

Great idea @Christian_83,subscribed

 

[kevbo]

Start with a prop that should be close. Raise or lower the trailing edge to adjust load. Generally throttle response is what you are going by, especially on smaller engines. There wont be much difference in top rpm between a perfect prop an one that is a little sluggish getting on the pipe.

 

[Christian_83]

I thought about calling Skat Trak to get more information and explanation about leading edge and trailing edge pitch, also if the impellers are born with same root angle or diffrent root angle.
Anyone who knows this?

 

[cookn]

It seems all manufactures just send you whatever they have on the shelf and grind the number you ordered on it

 

[jo5hi3]

I thought about calling Skat Trak to get more information and explanation about leading edge and trailing edge pitch, also if the impellers are born with same root angle or diffrent root angle.
Anyone who knows this?

I actually talked to Skat about this. He told me for a 155 Yamaha prop they only have 2 molds. So there is only two different root angles. He told me that he uses one mold for everything below 14 leading edge and the other for anything over 14.

 

[Aidan Burns]

I actually talked to Skat about this. He told me for a 155 Yamaha prop they only have 2 molds. So there is only two different root angles. He told me that he uses one mold for everything below 14 leading edge and the other for anything over 14.

So they’re pitching every prop by hand?


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[Big Kahuna]

So they’re pitching every prop by hand?


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Would say they are using pitching machines........ They throw really fast props!!!!!!!!

Pretty sure they have equipment they have built to do this. presses and such.

 

[Aidan Burns]

Would say they are using pitching machines........ They throw really fast props!!!!!!!!

Pretty sure they have equipment they have built to do this. presses and such.

I would not want to be on the business end of a pitching machine with a hopper full of props....


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[Christian_83]

I actually talked to Skat about this. He told me for a 155 Yamaha prop they only have 2 molds. So there is only two different root angles. He told me that he uses one mold for everything below 14 leading edge and the other for anything over 14.

Yeah i heard something about that, then another bird told me that 160mm Skat Trak impellers even with low pitch, are individual root angle.
Can anyone give a good solid explanation on leading edge and trailing edge, what does happen when you pitch up/down on leading. And same for trailing edge?