Saildrive Anode OK but hole in Prop - Any ideas?

[chelleon]

Just had boat lifted for new anti foul and anode replacement.

The Sail drive anode looks OK (2 years, so would expect a lot of erosion) but there is a hole in the prop!

Does anyone have any ideas why this would be happening

 

[Sandy]

Should there be a prop anode?

 

[Tranona]

Difficult to say without knowing what sort of prop and where the hole is. A photo should help.

Normally there is no reason why an aluminium prop should corrode except they get ratty at the edges if the paint gets knocked off.

 

[chelleon]

Managed to get an image up. The whole is in the middle of the spade.

 

[Tranona]

Old age and probably copper based AF has been used at some time. The propeller is electrically isolated from the shaft and the drive housing (assuming the isolating washer behind the cone is in place). Obviously need a new prop and while it is off remove the anode to make sure the contact with the housing is clean as the lack of wear on the anode is a bit concerning, although the housing looks OK.

 

[chelleon]

Old age and probably copper based AF has been used at some time. The propeller is electrically isolated from the shaft and the drive housing (assuming the isolating washer behind the cone is in place). Obviously need a new prop and while it is off remove the anode to make sure the contact with the housing is clean as the lack of wear on the anode is a bit concerning, although the housing looks OK.

Many thanks for your thoughts and suggestions. I will certainly take note of the mating surfaces and the isolating washer! when the new anode and prop are fitted tomorrow.