1kicker
Executive Member
Posts: 852
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Post by 1kicker on Oct 2, 2012 19:58:03 GMT -1
Have a 24 foot pontoon with a 115 hp 4 stroke with a 3 blade prop Pitch 14 X 11 and at WOT trimmed all the way down I turn about 6800 rpms which I believe is too mjuch and I will blow the prop at times if I stay at these RPM. In researching there is a 4 blade made for pontoons pitch 13.8 X 13. which is supposed to prevent cavitation/ventilation. Both props are the mercury alum props. Do you think this would put me at lesser WOT, allow me to trim some to get bow lift without having prop blow out. Your thought and opinions would be valued. Thanks Richard
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crizzel
Executive Member
Posts: 1,213
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Post by crizzel on Oct 2, 2012 20:49:10 GMT -1
If your motor was turning 6800RPM's it would have bit the dust by now. Sounds like your gauge is off.. I'd carry it in and let the shop check it out and re calibrate the gauge..
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1kicker
Executive Member
Posts: 852
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Post by 1kicker on Oct 2, 2012 22:14:58 GMT -1
Only got to 6800 a couple of times and did not hold it there for the reason you mentioned. I back it on down to the 5000 range.
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Post by Bob Smith (Porko) on Oct 2, 2012 22:32:16 GMT -1
Richard, your motor may be sitting too high in the water for that toon. Can you drop it down any?
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1kicker
Executive Member
Posts: 852
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Post by 1kicker on Oct 2, 2012 22:35:39 GMT -1
Bob, I will have to look again but believe it was all the way down now, but will recheck since I now have the boat out of the water.
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Post by Bob Smith (Porko) on Oct 2, 2012 23:17:47 GMT -1
From the sounds of it, you might not be getting good water on that prop. That's a whole lot of toon to get out of the water. Setting it lower will move the CG down enough to push the front of that toon up a little better.
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1kicker
Executive Member
Posts: 852
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Post by 1kicker on Oct 3, 2012 10:03:42 GMT -1
Bob, this is why I was considering the mercjury spitfire prop 4 blade which features extra hold and lift for pontoons. Take and google to see what I am looking at (Boat Propellers Mercury Performance part # 8M8026570.) Whats your take on this prop for pontoon. Stats say it should reduce rpms and provide life to front.
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Post by Bob Smith (Porko) on Oct 3, 2012 14:22:47 GMT -1
My only thoughts on that is the 13"P is awfully low. If you are spinning that many RPMs now (assuming you are running a higher pitch prop), then it's going to go nuts with a 13P prop.
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1kicker
Executive Member
Posts: 852
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Post by 1kicker on Oct 3, 2012 14:28:24 GMT -1
Bob now running 14 X 11 new 4 blade would be 14 X 13, am I off base on this.
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