Cavitation issue Mainship

[Skyboss]

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 !

 

[DavidM]

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.


David

 

[C lectric]

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.

 

[BruceK]

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.

 

[Keysdisease]

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.

 

[jleonard]

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.