Grete & Fred Vithen
Fri 3 Jun 2016 05:23
This doesn't look good at all.
We got lot of different advices from experts and sailor friends.
The best one was from our friend Tony Cross who took pictures and send them to Crusing Association in the UK.
This is the answer:
It looks very much like dezincification. The usual test is to tap it with a hammer. A prop in good condition should ring, whereas a dezincified one will make a dull thud. In some cases the metal will be so weak and brittle that a light tap will knock pieces off. The affected metal will be very red, there are several photos like this on my website.
There is no way it can be repaired. I asked Castle Marine about this last year. They are prop specialists in Caernarfon. They won't touch props in this condition as it cannot be determined how bad the damage might be.
Whether it is safe to use is the big question. I would grind/abrade back the surface corrosion to clean metal to see how much is dezincified. Coupled with the ring test this might give some more idea. I suspect they might get away with short trips in the meantime but care is needed.
It rings like a bell. What a relieve. But still we need to change it sometime in the future.
And the problem with corrosion has to be solved. We will add a anode to start with.
We had our Mastervolt Isolation Transformer checked. Nothing wrong with it.
And now we are also aware of something important called "clarity".