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Help!!! Major Cavitation Issues

Discussion in 'Technical Stuff' started by GatorBob, Aug 4, 2017.

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  1. GatorBob

    GatorBob New Member

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    I have a 2011 Bennington 2275GCW with 150 HP Yamaha and elliptical pontoons.


    I have had cavitation issues with this boat since the day I bought it 6 years ago.  Have had 3 different props on it, no change.


    Cavitation is worst with 5 or more people on the boat and if the water is at all choppy.  I have used all combinations of trim and seating configuration (moving bodies around in boat).  Nothing works.  Dealer gave up on it after 3rd prop (I paid for all 3!!!) and could never replicate the problem because they only had 1 or 2 bodies on board.  


    I don't understand why, but it occasionally occurs on our outward part of the trip but occurs almost 100% of the time after being out for hours (low speed) and then powering up on the return trip.  While the boat will go 38 mph top speed, it will start to cavitate on anything over 10 mph or even less - 7 mph.  Thus if I go out 20 miles, it takes me over 3-4 hours to return.  This is extremely frustrating and very embarrassing with passengers on board.


    I am at wits end on what to do.  I only take the boat out 2-3 times a year because of this issue.  In my 6 years of owning this boat, I have never had a day on the lake or gulf of mexico with 4 or more passengers when this did not happen.
     
  2. myv10

    myv10 Well-Known Member

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    Check your mounting holes, motor might be too high. I had some issues with cavitation and lowered the motor 1 hole, seems to be much better.
     
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  3. lakeliving

    lakeliving Well-Known Member

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    Weird. This is the first I've heard of this issue on an elliptical. Check motor height. Do you have a 20" shaft? 
     
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  4. adkboater

    adkboater Well-Known Member

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    Motor height or shaft length is definitely your issue, probably exacerbated by having multiple people in front of the centerline of the boat thus making it worse. Possiblely big cooler placement, live wells being filled etc. too. I'd start with the obvious and easiest and go from there. 
     
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  5. 1trotter

    1trotter Well-Known Member

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    A 4 blade prop may help as well.   :Like:
     
  6. GatorBob

    GatorBob New Member

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    The motor is already down as far as it will go.


    No coolers or bait wells in back. 


    I have moved people all around including all in back of boat.


    Nothing works.  Extremely frustrating!!!
     
  7. KC24

    KC24 Well-Known Member

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    Could the prop be to low?
     
  8. lakeliving

    lakeliving Well-Known Member

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    Have any video of this gatorbob? There are two elliptical bennington's on our lake, one has the 115HO and the other is a GCW with a 150. They both get on it all the time with no issues.


    Is your trim not dialed in in the back? There is an adjustment that could be limiting how far the motor is trimming down. Could be that the dealer never adjusted this. So it shows all the way down but isn't. Make sense?
     
  9. adkboater

    adkboater Well-Known Member

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    Going to throw a stupid thought in here.... does it have the wrong length shaft on the motor?? Maybe a 20" shaft instead of a 25"? Kind of make sense since this is been going on since new. 
     
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  10. 1Blderbob

    1Blderbob Well-Known Member

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    Really sounds like you may have a 20" shaft motor on your boat. You stated the motor is all the way down,but no mention of the motor shaft length. Damn you adk,you beat me to the punch by 4 mins.
     
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  11. adkboater

    adkboater Well-Known Member

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    Just checked the boat builder and the ellipticals call for a 20" shaft, need to double check the trim adjustments and make sure that it's dropping all the way down, and check the bushing in the prop, maybe it's just spinning around the bushing and it's not actually cavitating? 
     
  12. adkboater

    adkboater Well-Known Member

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    All I can say is my patience wouldn't last that long, I'd of got rid of the boat by now!! 
     
  13. kaydano

    kaydano Well-Known Member

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    Is exhaust gas somehow getting out of the engine in front of, or around, the prop instead of going through it?


    That's the only thing that comes to mind after hearing all the comments above...
     
  14. LT1GMC

    LT1GMC Well-Known Member

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    Did you find out an answer? I know some Yamaha's take a different mounting height than Mercs, (transom built different) maybe yours was built for a merc?
     
  15. basshawk84

    basshawk84 Well-Known Member

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    Is the prop really cavitating or is the boat porpoising? I had a problem with the bow of my boat bouncing up and down at WOT and I really couldn't use the trim effectively both with my original 115 HP and the 150 HP. I fixed that problem by installing a Cobra Edge Hydrofoil.
     

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