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#1
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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
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love to fish 
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#2
02-21-2012, 10:24 PM
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Got the fellas on iboats workin on it... I have a couple ideas but waiting to see what they think.
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#3
02-21-2012, 11:25 PM
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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.
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#4
02-22-2012, 11:10 AM
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Quote:
__________________
*************************************** Stay Safe!  Sold - 1984 V-20 Cuddy with a 2003 Johnson 140 hp gas sippin 4-stroke. 1995 Ranger 250C with a 2015 Suzuki 300 hp 4-stroke.
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#5
02-22-2012, 12:36 PM
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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.
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#6
02-22-2012, 01:58 PM
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whoops... double post
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#7
02-22-2012, 09:16 PM
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its my sons boat and i think he said 34mph,but he did tell me that when its about 3/4 of the way down the throttle and puts it all the way down he sees no differance in the speed. its a white prop that came with the boat, probably not a very good one but an all around prop, and it tachs out at 6400rpms, to high
__________________
love to fish
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#8
02-22-2012, 09:35 PM
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I'm betting that the tach is reading wrong.
__________________
*************************************** Stay Safe! Sold - 1984 V-20 Cuddy with a 2003 Johnson 140 hp gas sippin 4-stroke. 1995 Ranger 250C with a 2015 Suzuki 300 hp 4-stroke.
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