Anodes.

[haulyfryn]

I am in the process of buying a Dufour 32 Classic and have just lifted the boat out to check the hull and I noticed the anodes on the keel were badly eroded. The boat was anti fouled last August and the owner paid to have new anodes fitted but cannot guarantee it was done. (It is possible that the boat yard just did not replace the anodes) The anode on the sail drive has started to wear but is still good for this season. I replaced the anodes prior to putting the boat back in the water, but I am worried about what could have caused such rapid erosion. The boat had two anodes fitted to the bulb of the keel, but none on the rudder. Is this normal?
The boat is in a marina in the Med and there are a lot of boats connected to shore power. My question is, how long do anodes normally last?

 

[lpdsn]

The boat had two anodes fitted to the bulb of the keel, but none on the rudder. Is this normal?

The rudder will be fibre glass I guess.

My keel anodes last over two years. I replace one each year so they're left attached for two years. Not sure I'd trust the yard to do it without a quick check myself with the multimeter. Presumably the PO just left the yard to launch the boat.

If nothing else the anodes have lasted 11 months, so you're not facing a big risk. The anodes you fitted should get you to the end of the season plus some. Check out the electrics to see if there are any issues. It's not exactly a big secret that PBO is twinned with Impractical Electrics Bodger.

 

[Tranona]

Anodes on the keel are pretty much a waste of time unless it is a composite iron/lead keel. If it is plain cast iron there is very little galvanic action because it is all one metal and not attached to anything else. what erodes your anode is the impurities in the iron, but f you did not have the anode nothing would happen. There is no chance of your keel eroding away without the anodes and they do nothing to prevent rust which is the biggest problem with iron keels. Nothing to worry about from other boats either for the same reason the keel does not require anodes. It might make sense, however to fit a galvanic isolater to your shorepower input if it s earthed to your DC system.