Rapidish Anode Wear

[willfinch36]

After 6/7 months of being in the water my pear anode has worn to almost nothing - Also a bit of pitting on the keel.

I'm pretty sure the first year I owned the boat it didn't wear as quick!

Any thoughts?

Sail drive anode appears ok and replace the 3 piece folding prop anode every 6 months anyway.

Thanks,

Will

[Symphony]

What is your anode connected to? There is normally on a Bavaria nothing that needs that level of protection. Trace the wire inside and see what it is bonded to.

[willfinch36]

Thanks, will do just that.

[dawntreader]

You also don't mention the state of your prop anode (split ring type). I also have a B37 2006 model. The only anode I have is the one fitted behind the prop. I replaced it for the beginning of last season - 10 years in place and still >50% original weight. I worried about the lack of erosion to the anode for years but several conversations with Volvo engineers at different boat shows suggested I was doing the right thing: disconnect shore power when not using it; fitted a galvanic isolator; switch batteries off when not on the boat. We live aboard at least 8 months of the year in various European marinas and so we are exposed to the potential for anode 'wear'.

[Impavidus]

Hi Will. are you certain it was a salt water anode and not a fresh water one? Just a thought. There is a good discussion on this subject here http://www.bavariayacht.info/forum/index.php/topic,1201.0.html
 
Ant.

[tckearney]

Are you in a marina?   It could be a problem with the marina electrics.  I have a B42 and only anode is the saildrive anode and it never wears, so something is causing it.  The others owners are correct in switching off batteries and in particular mains when not in use.  If in a marina you could try dangling an old anode over the side between the pontoon and your boat and connect it to a multi meter on milli volts dc .  If you get a substantial reading on one side but not the other, then you boat is reacting with the metal of the pontoons. Put  + lead to anode - lead to engine casing. Let it sink to about 1 meter under water. (not the meter obviously) see if you get a reading.  Maybe worth trying the same on the none pontoon side.  I am not an expert on this but do have some experience with steel hulls on ships that have been laid up for long periods.

[Impavidus]

Just thinking this through???..
I am pretty sure your sail drive is isolated from the engine on the Volvo. (See the diagram from my D130/S130, installation manual, my other boats have had similar isolation so I am assuming yours is the same.) There are a set of fine hard plastic washers and some dark art plastic gasket thingy that are mentioned in the service/installation manual.
The sail drive anode is fine so it?s not a problem. The prop anode is, as with many folding props designed to disappear ASAP so you have to buy a very expensive ?special anode? every six months? Or build a bigger better one yourself?
The teardrop anode is connected to your engine earth, back to the batteries and the mains earth via your charger and the earth link. Also your keel should be earthling your mast against lightning strike and as exposed metal be earthed to the battery and via the aforementioned, and the mains earth?
So if the teardrop anode is dissolving but not the leg anode, it must be an issue associated with the earth/negative on the boat (or someone else?s boat or piles/metalwork in the water around you?)
I would suggest this is ?stray current?. Basically your teardrop anode is working exactly as it should do, eroding and protecting something else, or someone else?s boat.
I have seen someone fit a fresh water anode from a boat jumble to their boat and it disappeared in months. But if you arer happy it was a Zn anode (Zinc) it must be a problem with stray current via your earth connection.
Even with the batteries turned off and the mains power off the problem will still be there, if the mains cable is plugged in (via the earth) as the earth remains connected even when the main breaker is off!
Unless I am missing something?..  You can turn off the battery isolator and remove the power lead from the socket. Or fit a galvanic isolator in the mains power circuit earth line. 
I had the same problem on my 37 when I first bought it. The standard Bavaria anode  dissolved quicker than Steradent in a glass of full of teeth and water! The galvanic isolator I fitted has ensured someone else?s anodes disappear, while my batteries stay charged and my boat dry and warm all year round 
Hope this makes sense and is of use.

Ant .
 

[Symphony]

Bavaria only introduced hull anodes recently to comply with the RCD that the boats electric system should be bonded to one. It does not actually protect anything. The only thing that needs protection is the saildrive housing which is what the ring anode is for. That does nothing for the prop which is electrically isolated from the drive housing by the washer behind the prop. The aluminium prop does not need an anode, but many folding or feathering props do because they are made of mixed metals. Often they erode very quickly and it is virtually impossible to increase the anode size.

If the OP's boat is the older type then it would not have an anode fitted from new, noe does it need one. Hence my suggestion he finds out what it is connected to.