[C320-list] P-Bracket Dezincification

[Dennis Cookson]

I had a marine engineer booked to replace my cutlass bearing today but things didn’t go exactly to plan. After removing the propeller he fitted a Strut-Pro tool to push out the old bearing but immediately found that the leading surface of the P-bracket/prop strut sleeve around the bearing started to flake away revealing a bright pink rough area. This is apparently bronze that has become dezincified, whereby the zinc content of the bronze has been leached away by either chloride corrosion or galvanic corrosion. Either way, it is irreversible, and the engineer informed me that the P bracket would need to be replaced as it would be weak and prone to further damage.

I’m wondering if any other 320 owner has encountered this, or has knowledge of why it might occur. I replace my sacrificial zinc anode annually, which is bolted to the hull, and grounded. I haven’t yet determined whether the P-bracket is connected in the same way. We’re rarely connected to shore power as the boat is kept on a swinging mooring during summer months and lies on the hard over winter.

Is your P-bracket bonded to your electrical system?  Or do you have a zinc anode fitted directly to the bracket, as suggested by Catalina Direct <https://www.catalinadirect.com/shop-by-boat/capri-26/engine/props-etc/prop-strut-zinc/>?

Dennis Cookson
‘Catalina’ #0577