When we bought this boat the PO had been very upset with the bottom paint job they had done in Florida.
The boat was hauled and was bottom painted in a "no self service" yard on Florida's East coast. When the yard monkey painted the bottom he also painted the Aquamet prop shaft and the Manganese Bronze prop despite the PO asking them specifically not to do this.
The PO was furious when they painted it with regular copper ablative paint but they would not allow any DIY, and insisted on charging him to remove the paint, so he launched and figured he'd keep up with the zincs.
The boat also has a galvanic isolator but from the time the prop was painted until they hauled out in October they stayed in four or five marinas max between Florida & Maine. The rest of the time was on the hook cruising. The boat was in the water like this from May through October and the Zinc was changed once and still in good condition when I bought the boat. Norm claims the prop was in perfect condition before they applied the bottom paint. He is and was a meticulous PO so I can only trust his judgment and he knows what dezincification looks like.
Many, if not most, in board sailboat boat props are made of Manganese Bronze. Some are also made from NiBrAl a nickel/bronze/aluminum alloy. Manganse bronze contains upwards of 40% zinc content and zinc contents over about 15% are very susceptible to dezincification. Painting it with copper bottom paint can lead to dezincification of the alloy and eventually make the prop worthless as there is no way to fix it other then to melt it back donw and recycle it.
H&H Prop, one of the prop shops I use up here, recommended I retire it to the scrap heap when I asked if it was repairable or safe.
Please for your own good use a proper underwater prop paint or none at all and what ever you do please avoid copper based bottom paints on Manganse Bronze props. This wheel is a Michigan MP which is the same prop that comes standard on Catalina, Hunter and many other boats..
The pinkish, coppery colored areas are where the zinc content has been eaten away leaving behind only the copper in the Bronze alloy..
The boat was hauled and was bottom painted in a "no self service" yard on Florida's East coast. When the yard monkey painted the bottom he also painted the Aquamet prop shaft and the Manganese Bronze prop despite the PO asking them specifically not to do this.
The PO was furious when they painted it with regular copper ablative paint but they would not allow any DIY, and insisted on charging him to remove the paint, so he launched and figured he'd keep up with the zincs.
The boat also has a galvanic isolator but from the time the prop was painted until they hauled out in October they stayed in four or five marinas max between Florida & Maine. The rest of the time was on the hook cruising. The boat was in the water like this from May through October and the Zinc was changed once and still in good condition when I bought the boat. Norm claims the prop was in perfect condition before they applied the bottom paint. He is and was a meticulous PO so I can only trust his judgment and he knows what dezincification looks like.
Many, if not most, in board sailboat boat props are made of Manganese Bronze. Some are also made from NiBrAl a nickel/bronze/aluminum alloy. Manganse bronze contains upwards of 40% zinc content and zinc contents over about 15% are very susceptible to dezincification. Painting it with copper bottom paint can lead to dezincification of the alloy and eventually make the prop worthless as there is no way to fix it other then to melt it back donw and recycle it.
H&H Prop, one of the prop shops I use up here, recommended I retire it to the scrap heap when I asked if it was repairable or safe.
Please for your own good use a proper underwater prop paint or none at all and what ever you do please avoid copper based bottom paints on Manganse Bronze props. This wheel is a Michigan MP which is the same prop that comes standard on Catalina, Hunter and many other boats..
The pinkish, coppery colored areas are where the zinc content has been eaten away leaving behind only the copper in the Bronze alloy..