Now I have lifted my Hanse and there is pitting corrosion in the rudder stock. Its the original, so 13 years old, the pitting is prob less than 5mm in depth at the most. Any experience with this? Also, ever heard of leak from the water tanks? I have water in the bilge, it's not salty, and not coming in from outside. I thought of dumping food colouring into the tank and see if it comes into the bilge to confirm. What do you think?

Jorgen

I had some minor rudder stock pitting which I noticed when I replaced the rudder bearings.

I had an expert take a look and was told that it was nothing to worry about but to get to the source of the issue so that it doesn't go any further. I had a marine electrician do some testing and he found that there was a very small electrolytic current at the stock, he noted that the stock had no hull anode and was not grounded anywhere. He suggested that I run an earth wire from the stock to one of the bolts on the engine as the engine has the saildrive anodes. This was any small charge will eat the saildrive anodes before it eats the rudder stock.

Many Hanse yachts are fittted with Jefa manufactured rudders; many are not however Jefa have several website pages dedicated to electrolytic corrosion and how to prevent it.

https://jefa.dk/electrolysis/" rel="nofollow - https://jefa.dk/electrolysis/

We discovered very very slight pitting on our 7-year old stock during recent haulout along with more sail-drive/thruster anode corrosion than anticipated. We carried out Jefa's recommended insulations/isolation checks noting Coppercoat had been applied around and into the shaft/hull joint which is not recommended so we removed 100mm of Coppercoat from the area and used a conventional ablative antifouling. We also now longer leave short power cabled connected when leaving our boat relying on wind/solar to keep batteries healthy until an isolation transformer can be fitted.

Suggest you read the Jefa electrolytic corrosion website pages.

Cheers.

Solid , pls look on

https://jefa.dk/products/rudder-stocks/" rel="nofollow - https://jefa.dk/products/rudder-stocks/

Jefa recommended not to make a bounding wire between the rudderstock and the earth.Hanse did this on some models somewhere between  2007-2012. There where some discussions between Jefa and Hanse about this. See topics.

IMO Leave it completely isolated and if there is a earth cable between the ruderstock and the keel-tanks-engine etc remove it from the rudder.

I removed it from the first year 2010 and no corrosion at all even in the warm and salty waters of the east Med.

We have a big zinc anode on the hull connected to the earth bounding wire(keel-tanks- engine etc.) on the hull nearby the rudder.

A common source of water leak is  the pressure reducing valve on the calorifier.  Pressure bulds up as the hot water expand and this can also cause  some joints to leak.  When we start the engine or switch the heater on, we turn off the water pump and relax the piping system by running a tap for a few seconds.  After the water is hot you can turn the pump back on.  

Really dry the bilges and monitor them very closely as the water tracks all over the place and some areas only empty as the yacht heels..  Does the water leak when the pump is off, if it does not then that says the tank and piping to the pump is not the problem.

Do not bond the rudder stock, the rudder sits in synthetic bearings and the autopilot drive arm is on synthetic bushes so its not possible for the rudder to pick up stray current from the vessel. having the rudder isolated is the best way to protect it. It is however able to pick up stray current from the bonding wire if there is an issue with termination, leak in and around the boat from neighbours etc.

Bonding to the engine is not great idea as saildrive anode is designed only to protect the saildrive mass, not the engine, not the keel, not the rudder and many of older Hanse have all of these elements bonded together. All this will do is cause the saildrive anode to waste rapidly and once its gone the enxt inline will sacrifice. The saildrive anode is aluminium, the hull anode is zinc, means hull anode has holiday doing nothing while saildrive anode does all the work. Of most concern is cable that joins the DC neg bus bar and AC earth bus bar meaning anything bonded is also connected to earth of the pier for better or worse. Your anodes will waste away in matter of weeks/months. (see my detailed posts under my user name on removing the AC-DC connection).

I had communications with Jefa when i replaced my rudder and they confirmed they disagree with Hanse's approach to bonding the rudder and recommend its left isolated and correct antifouls used.

A big call out to Stephen for his ongoing help on this subject, his vigilance on the ongoing threads is tremendous.