# Spoke to soon......25 merc on Stumpknocker



## No Bait / Lures Only (Apr 10, 2011)

Aluminum prop with no cup is probably the problem, sra PT should fix the blowout issues. Give Power Tech a call......


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## DuckNut (Apr 3, 2009)

yep...too high


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## Bigkahuna (Sep 16, 2007)

I appreciate the input...I put this up on iboats and got some good info as well. I'm just trying to get this thing to run skinny....


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## HaMm3r (Dec 11, 2006)

That isn't too high, you're just not propped right. I agree with the PT SRA recommendation. I ran a 4 blade 15 pitch on my Merc 25 that was jacked up to a similar height. You could also add a hydrofoil which will help with cavitation a lot. The SE200 worked well for me.

Here's a video showing my current running heights with combo jackplate/TNT, PT prop and hydrofoil on a modified Merc/Hatsu 30HP 2-stroke.
[media]http://www.youtube.com/watch?v=1fq1oBb_0Vg[/media]
http://youtu.be/1fq1oBb_0Vg


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## cutrunner (Jun 8, 2010)

Its hard to say because every hull is diffe[ch341]ent. In my opinion its way high. I had a somewhat similar flat bottom skiff with even more setback and the highest i could get the cav plate over the hull bottom was maybe 1/2 inch.. but that was with a 3 blade


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## DuckNut (Apr 3, 2009)

Agree with cut. The flat bottom and the boats draft is so little that there is not enough water above the prop.


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## No Bait / Lures Only (Apr 10, 2011)

PT-SRA VS TURBO HOT SHOT 3 Blade props on a flat bottom skif : The turbo is faster, but have to run it very low on the transom as the cupping is very little. The pt-sra is good very high on the transom, a little slower top speed. You have to make a choice higher/lower, 1mph difference in speed..Compromises......... :-/


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## lil_kahuna (Sep 23, 2011)

*Update*: lowered it 2" and it will plane..takes a few but getting closer. Set at the lowest hole and cat plate is 1" above pad. That's the lowest I can set it due to tiller clearance. I'm definitely gonna have to reprop or look in cupping mine. Any input on self adjusting tabs? Thanks


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## jwarren (Aug 23, 2013)

I had near identical set up until I sold my Stumpnocker a month ago and I did extensive testing. I used a homemade jack plate and raised my 18 hp Nissan about 3" with only 1.5" setback in the riser. I put an SE200 on the motor and that was the key. It jumped the boat up on plane in NO time and put the bow down. It dramatically improved handling and turns with no blowout. Did all this with stock prop. Get a tach meter and record your mph and rpms at different heights and trim tab settings.


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## jwarren (Aug 23, 2013)

I had near identical set up until I sold my Stumpnocker a month ago and I did extensive testing. I used a homemade jack plate and raised my 18 hp Nissan about 3" with only 1.5" setback in the riser. I put an SE200 on the motor and that was the key. It jumped the boat up on plane in NO time and put the bow down. It dramatically improved handling and turns with no blowout. Did all this with stock prop. Get a tach meter and record your mph and rpms at different heights and trim tab settings.


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