what's up with my rudder??

I am pretty sure that is the result of cavitation affecting your rudder.

With that said a buddy had his Malibu Skier docked at his dads dock on the Sacramento River for a year. He went down to use it and the battery was dead so he ran a cord down to the dock and hooked up a batter charger.   He left it for a couple weeks hooked up and in the river current.   The battery charger somehow caused electrolisis and it ate at his rudder, Prop and Fins. He had to replace them.   I never got to see the bad parts but he told us the story.

If your rudder looks like this what does your prop and fins look like?

Damn that’s heavy. How deep is the pitting?

MrMcD wrote: I am pretty sure that is the result of cavitation affecting your rudder. With that said a buddy had his Malibu Skier docked at his dads dock on the Sacramento River for a year. He went down to use it and the battery was dead so he ran a cord down to the dock and hooked up a batter charger.   He left it for a couple weeks hooked up and in the river current.   The battery charger somehow caused electrolisis and it ate at his rudder, Prop and Fins. He had to replace them.   I never got to see the bad parts but he told us the story. If your rudder looks like this what does your prop and fins look like?

MrMcD - yeah, it wouldn't be electrolysis.   I have noticed very small pitting starting over the course of the last several seasons. I very rarely put my boat on a charger during the season anyway.   I have definitely notice this get MUCH worse since I changed out the props just a few short weeks ago.

My Fins are nice and smooth, and my prop is shiny new.

Yeah Ken...I think I"ll REPLACE the rudder next spring, for the remainder of this season, I'd just like to repair it.   For a temporary repair with Epoxy, do you have a "how to" or any advice?    Or is it as simple as mixing up a two part epoxy, and filling in the "cavitation" and then smoothing to match surface??

Dan,
I've had very good results repairing cavitation worn pump volutes and casings with epoxies. I remember one pump I needed to repair every 6 months because the pipe fitter made the classic mistake of installing an elbow within 12 times the pipe diameter to the suction side of the pump causing the cavitation. Devcon has been around for many years and is my preferred

Ken, I was thinking the picture above looked like the prop was pretty close to the rudder.
Went down and took a picture of my prop on the 95 Nautique. Distance looks the same but I note I should have used stainless set screws on the cutlass. My set screws show rust already.

The battery charger electrolisis I understand would not happen in standing water but in the ruver current the moving water creates the effect that ate away at my buddies Malibu parts.
I was told many boats that sit in the river have had this happen if they hook up battery tenders or chargers. I am sure someone understands why.

Mark

The picture I put up was from Aussienorts a handful of years ago

Your picture and that one should give him something good to compare to.

Electrolysis removes unwanted, unsightly hair right Pete?

Well, I can pretty much tell you HOW it happened.....1. the rudder is Original to the boat..so it's OLD, and it did have some slight cavitation happening in those spots over the last couple of years. 2. I replace the Original 4 blade OJ prop, with a new 3 blade 540 Acme prop.

That's ALL that's been changed.   I will do measurements of prop to rudder, etc when I get back up north to our place. The boats up there.

yeah...my rudder (and boat) is pushing the 2400 hour mark. Still runs like a champ. I did JB weld in those spots and it seems to be holding up well. Will replace rudder either later this fall, before I winterize, or next spring.

Netdewt wrote: What is cavitation, and what causes it?

8122pbrainard wrote: Different areas of cavitation corrosion: Some interesting reading on the subject