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Old 12-14-2019, 12:26 PM   #1
Skyboss's Avatar
City: Cape Coral
Country: USA
Vessel Name: Skyboss
Vessel Model: 2005 Mainship Pilot
Join Date: Apr 2016
Posts: 17
Cavitation issue Mainship

Hey everyone, I'm looking at a 34 Mainship Pilot 2 that the broker says cavitates above 2000 RPM.He says he tried to put on 5 blade prop to mitigate issue but didn't work. Also says previous owner extended keel for some reason ( I assume the same). Any ideas ? Thanks !

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Old 12-14-2019, 12:33 PM   #2
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City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23
Join Date: Aug 2012
Posts: 5,052
Search for pilot cavitation and you will find several threads on the subject. No need in repeating for this thread. Your broker's seller is the first that has reported trying a 5 blade prop. Surprised it didn't help.


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Old 12-14-2019, 08:57 PM   #3
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City: Gibsons, B.C.
Country: Canada
Vessel Name: Island Pride
Vessel Model: xxxx
Join Date: Oct 2007
Posts: 2,639
Single engine with a Keel ahead of the prop? Is the keel back end very blunt?

A couple fellows I knew with very different boats reshaped their keel just ahead of the prop. so the water could flow better instead of creating vortices.

One of them was a shipwright and he had done the same to a couple other boats for noise reduction.

Consider it. A blunt, wide keel end may make the boat prone to this.
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Old 12-15-2019, 01:04 AM   #4
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Skyboss, you are fortunate to deal with a frank and informative sellers broker. Hope you find the answer, there must be owners of those boats who know, it`s likely to be a well ploughed meadow.
Island Gypsy 36 Europa "Doriana"
Sydney Australia
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Old 12-15-2019, 06:48 AM   #5
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City: South Florida
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Originally Posted by BruceK View Post
there must be owners of those boats who know, it`s likely to be a well ploughed meadow.
This issue is indeed well plowed. The Mod C Electric mentioned is called "keel fairing" in the Mainship community. A former faithful Attitude Adjustment Jay was the first or one of the first to do it on a Mainship MKI. I did it on my olde MKI as well, although this was not the typical "fix" for the Pilots.

I will also echo what David said about the 5 blade, which was the typical solution.

As mentioned, this is well plowed, search here and the Yahoo site and you will find more than you ever wanted to know.

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Old 12-15-2019, 07:55 AM   #6
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Join Date: Jun 2008
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This is a pic of the fairing job I did that solved the vibration problem on my old 34 Mainship.
It's just 2 blocks of pressure treated 4x4 that I rough shaped, epoxied to the hull, then finish shaped with a grinder and fiber glassed it all to the hull.
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Jay Leonard
Attitude Adjustment
40 Albin
Mystic,Ct. /New Port Richey,Fl
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