Author Topic: High Rpm, no acceleration when pulling tubers  (Read 5383 times)

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Offline not2worried

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High Rpm, no acceleration when pulling tubers
« on: July 05, 2010, 05:11:45 PM »
Went out this weekend. Boat ran good. But while trying pull the kids on a tube, the boat would begin to pull, start to incline. I began giving more throttle to level it out. The Rpms climbed, but was not going any fast.
Is this a prop issue? Air in the water?  The area in which this happened was somewhat weedy. I have pulled people on a tube before much heavier then my young kids. Didn't really experiment to much. It happen a 2-3 times..but not every time. Thoughts?
1985 SSV 167    THE MARSHMALLOW
115 Hp Merc

Offline Rich_V174SS

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  • 1967 V174 Crestflite SuperSport Modified
Re: High Rpm, no acceleration when pulling tubers
« Reply #1 on: July 05, 2010, 05:32:02 PM »
Sounds like you've spun the hub in your prop. I would try a different one and have the prop re-hubbed by a reconditioning shop.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline Rosscoe

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Re: High Rpm, no acceleration when pulling tubers
« Reply #2 on: July 06, 2010, 08:30:29 PM »
Erik
Did this issue go away after out of the weeds and did it go away when not pulling a tube? Didnt even seem to notice there was a tube behind it a couple of weeks ago when we were out.
Ross
61 Surflite 1964 90HP Johnson project
67 V163 Bayflite Super Sport  1989 100HP Merc
67 V164 Bayflite 120HP
67 V174 Crestflite Rat Rod
71 V175 Crestflite 350ci -Jet
73 GT 160
84 CVX 17  83 115 Merc
88 CVX-23 350 Mag

Offline not2worried

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Re: High Rpm, no acceleration when pulling tubers
« Reply #3 on: July 07, 2010, 06:37:02 PM »
I didn't that much of a chance to check. Without the tube it was not there for sure. It seemed to be mainly in the weeds. Plan to try again this weekend. It was only a few times. and pretty much right after each other.
1985 SSV 167    THE MARSHMALLOW
115 Hp Merc

Offline Eric_Michael

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  • '83 CVX-16 / 175 HP
Re: High Rpm, no acceleration when pulling tubers
« Reply #4 on: July 08, 2010, 02:34:59 PM »
Just an odd thought... 

Maybe this is simple prop cavitation.  The extra drag of the tube is causing the prop to cavitate easier.  This is not necessarily a bad thing, especially with a 2-cycle motor.  It allows the motor to get into its power band sooner instead of struggling at a low RPM.

I have two props that I use.  The big wheel has been cupped so it cavitates easily.  It keeps the motor from lugging down when starting out.  The little wheel is not cupped and will launch the boat like a bullet (although I don't like to stress the transom that much).  It will bite the water better which makes it suited for the lower speed towing.

As an aside...  The big wheel will hit 61mph or so at right around 5000rpm.  The little wheel comes really close at a 59mph, and 5500rpm.

(Sorry, memory eludes me on the numbers for each prop.  I will have to check if someone wants to know.)

-Eric

Offline Hyperacme

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Re: High Rpm, no acceleration when pulling tubers
« Reply #5 on: July 08, 2010, 03:52:08 PM »
Might just have been weeds wrapped around prop ?

Offline Rosscoe

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Re: High Rpm, no acceleration when pulling tubers
« Reply #6 on: July 09, 2010, 01:08:30 PM »
Hopefully it was just weeds. Sure sounds like it if it went away. Next time (if there is one) stop right away and lift the motor and check.
Ross
61 Surflite 1964 90HP Johnson project
67 V163 Bayflite Super Sport  1989 100HP Merc
67 V164 Bayflite 120HP
67 V174 Crestflite Rat Rod
71 V175 Crestflite 350ci -Jet
73 GT 160
84 CVX 17  83 115 Merc
88 CVX-23 350 Mag