prop pitting

Menace2Authority

Seaman Apprentice
Joined
Jun 11, 2010
Messages
38
For the life of me I can't get the search function to work in my favor. My prop has pitting in the blades and calcium spots all over. Also my trim tab anode his pitted all to beat hell on the port side. The trim tab however was turned towards starboard side sightly.
Is this pitting of the prop and anode a prop problem? The bottom of the boat looks good and there is nothing hanging down below the boat (transducers etc.)
Motor is 1979 mercruiser 165hp with mercruiser drive.
I guess I'm basically wondering if the wrong prop could cause this. Its an old boat I just bought this year and god only knows what's been frankensteined.
Thanks

Rob
 

Darxen

Recruit
Joined
Jul 25, 2010
Messages
1
Re: prop pitting

Prop Pitting is usually a result of CAVITATION with the prop. Once it is pitted, with exposed aluminum, then white calcium deposits,,flaking is a result of the bare aluminum metal.

Typically, Cavitation is caused by the prop that has to much pitch, which creates a very low pressure on the back side of the prop, which lowers the point tht water boils to a very low temperature, causing little steam bubbles to form, that will then make the cavitation worse. Now, cavitation is normally caused by the prop sucking AIR from the surface down onto the prop, so I am not sure if that is the correct term,,but that will also cause pitting of your prop. But I think if you do not protect your prop with a good paint job,,eventually it will pit,,and then the aluminum will start to decay, causing the white powder,,when it's dry to form !

Keep your prop free of any nicks,,etc..keep it painted, and maybe try a little lower pitch ! Most likely, just good prop maintenance with removing nicks and dings,,and primer and paint will resolve the problem.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: prop pitting

Sounds like an electroylis problem.your anode is supposed to corrode instead of the motor and or prop. If someone used the hull of the boat for a ground in an ecectric circuit that could cause problems.If another boat in the Marina has a problem it could affect your boat.If the marina has a problem it could cause problems. Are you in brackish waters or salt?Our boat spends April to December in the water with the motor down in the northeast and my prop does show slight pitting. I don't know if there are any bonding straps on an I/O linking outdrive,boat and motor.
If your prop hasen't been off in years you might pull it and clean and grease the shaft.Be sure the nut is not loose.
 
Top