Fouling on prop problem

[Geitz]

I'm not sure if this is the correct forum for this, but has anyone seen this
sort of fouling and what might be causing it? We've had the boat for 6 years, the first four seasons at SSYC in Milwaukee, and the last two seasons at McKinley Marina. Both seasons at McKinley we've had this chalky buildup on the prop. In 2020 the prop was the two blade fixed that came with the boat. In 2021 I installed an EWOL stainless steel feathering prop. After the first season (2020), I installed a galvanic isolator, thinking that we were the ground for someone else's stray current, but it didn't help.


We had a magnesium anode on the prop shaft, but removed it later in the season because I thought we may have been overprotected. The boat is a Jeanneau S/O 36.2. Nothing is bonded. The boat has been on Lake Michigan since 1999 (new) and we've never had any problems like this until berthing at McKinley.


There is also some pitting / oxidation? on the p-bracket and etching of the bottom paint (VC-17) on the hull directly above the p-bracket and prop shaft.

[Orion Jim]

Are you the only one in the marina experiencing this issue? Were the yard crew shocked to see this? I’ve never seen anything like this…….

[tkeithlu]

Bond the boat, with magnesium anodes. It's freshwater, but you've set up a battery of some sort, given the pitting and growth.

[Geitz]

Originally Posted by Orion Jim

Are you the only one in the marina experiencing this issue? Were the yard crew shocked to see this? I’ve never seen anything like this…….

I'm not sure if I'm the only one. I've asked the marina manager if anyone else experienced it, but she said she has not heard from anyone.


We were all shocked to see it.



Mike

[fstbttms]

Originally Posted by Geitz

We had a magnesium anode on the prop shaft, but removed it later in the season because I thought we may have been overprotected.

I don't understand why you would do this. What indication did you have that you were "overprotected"?

[Geitz]

Originally Posted by fstbttms

I don't understand why you would do this. What indication did you have that you were "overprotected"?

I found an article from a company in Australia that described the problem (i'll try to find it to share), as well as this thread:


https://www.cruisersforum.com/forums...ft-249441.html


We've had the boat for 6 years. For the first 4 years the only anode on it was a prop-nut zinc, which I never replaced because there was no corrosion anywhere. The shaft, prop and p-bracket always looked as good as new. As far as I know, there has never been any other anode since the boat was new. I added the mg anode, just in case, the last season the boat was at SSYC. On haul-out, there was no calcareous buildup but the prop looked like it got plated from the mg anode. No problem until moving the boat to McKinley.

[Geitz]

One other thing that might be notable, there was always a current running through the harbor at SSYC. At McKinley, it's dead calm.

[sailorboy1]

I notice it is only on the prop, including the zinc. It isn't on the shaft or strut. What does the prop look like after you clean all that off?

[Geitz]

Originally Posted by sailorboy1

I notice it is only on the prop, including the zinc. It isn't on the shaft or strut. What does the prop look like after you clean all that off?

It looks like new. It's an EWOL stainless feathering prop that is not polished, but bead blasted.



https://ewol-propellers.com/e3-andromeda/