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Rudder post corrosion |
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High Time 
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Joined: 04 September 2012 Location: Portsmouth UK Status: Offline Points: 819 |
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 Posted: 24 October 2015 at 17:24 |
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The sail drive should be electrically isolated from the rest of the boat (as should the rudder) - either by careful insulation between the saildrive and the engine, as found on all recent Volvo engines, or by giving each engine mounted electrical item a separate 'earth' (negative return) wire, otherwise, as "Jefa" indicates above, there is a serious risk of the saildrive disintegrating.
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Roger
High Time (415 #038) |
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High Time
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Joined: 04 September 2012 Location: Portsmouth UK Status: Offline Points: 819 |
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Posted: 24 October 2015 at 17:29 |
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I have just inspected my rudder and am relieved to see that it is electrically isolated i.e. 'not earthed'.
High Time was build number #38 so, hopefully, all 415s thereafter (at least) should be similarly isolated.
Edited by High Time - 24 October 2015 at 21:05 |
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Roger
High Time (415 #038) |
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Rod
Commander 
Joined: 11 March 2013 Location: Dubai/Gocek Status: Offline Points: 124 |
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Posted: 25 October 2015 at 13:17 |
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All,
Where exactly is this bonding cable meant to be attached - if there ? I have had the panel up the last few days and also been into the transom space - yet do not see any yellow / green cable attached , neither a hull anode. Ref the saildrive being isolated - I can confirm that mine is - I have a sonic system fitted to the boat and in these hot water have massive growth on the prop and saildrive , every few weeks, yet minimal on the hull, thus assume that the rubber seal between the hull and saildrive is working.
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Hanse 415 - "Ti"
Gocek, Turkey. |
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High Time
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Joined: 04 September 2012 Location: Portsmouth UK Status: Offline Points: 819 |
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Posted: 25 October 2015 at 14:58 |
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Hi Rod
If your 415 is a higher (later) build number than High Time then you probably don't have the bonding wire - which is good. One way to get an indication of whether the rudder is isolated is to use a multimeter on the resistance (Ohms) range. Put one probe on the rudder stock and put the other probe on the galvanic isolator connections in the port locker, probably the bottom contact (if it's wired like mine) where a green/yellow wire is attached. (I suggest you disconnect mains power first to avoid any confusion with marina earthing). You should get a reading of a few hundred ohms with the probes one way round and probably a negative reading the other way round. That is OK. The rudder is forming a battery with the keel (and seawater) and the multimeter is completing the circuit; reversing the probes reverses the current flow. If you get a very low reading (less than an ohm or 2 then the rudder is connected to boat earth (which is bad). Regarding saildrive isolation this is electrical isolation, not mechanical isolation which is what you are noticing with the sonic antifoul system. Try measuring the resistance with the multimeter again between the saildrive and the engine. A low resistance reading indicates they are NOT isolated (which is bad). I hope the above makes sense to you. If not come back and I'll try again. PS The above only applies to boats with the Volvo engine and saildrive. Yanmar equipped boats have a different earthing set up. Edited by High Time - 27 October 2015 at 10:48 |
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Roger
High Time (415 #038) |
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StavrosNZ
Rear Admiral 
Joined: 24 October 2014 Location: New Zealand Status: Offline Points: 581 |
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Posted: 27 October 2015 at 02:07 |
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Hi Alidal,
I see you have a 400 as do i, on our boats the rudder, keel, hull anode and engine are all earthed together, you will see yellow and green stripped wires all labelled i.e keel on your electrical buzz bar under the instrument panel behind chart seat. The engine earth goes to the negative DC Buzz, the rudder, keel and hull anode all go the the AC earth Buzz, some genius at Hanse then connected the AC and DC buzz bars together with a large 12mm yellow and green strap. What this means is that the rudder, keel, engine/saildrive and hull anode are all earthed together. Yammer use aluminium anodes for the sail drive, the aluminium sail drive anode is lower on the sacrificial scale than zinc (hull anode) so the hull anode does not wear and infact does nothing whilst the sail drive anode which was only ever designed to protect the sail drive/engine alone is now trying to protect the sail drive, engine, keel and rudder and guess what, it wastes away in about 3 months............sound familiar? Answer is simple, disconnect the large earth strap between the buzz bars, this will result in separating the circuits so that sail drive anode only has to deal with sail drive/engine (DC buzz only) and hull anode now deals with rudder and keel separately. When new i was replacing sail drive anodes every 3 months, since separating the 2 buzz bars my sail drive anode goes 18-24 months and hull anode about the same.
Edited by StavrosNZ - 27 October 2015 at 23:37 |
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Stephen
2010 H400 #691, Auckland, New Zealand |
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alidal
Captain 
Joined: 30 September 2010 Location: Norway Status: Offline Points: 297 |
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Posted: 27 October 2015 at 06:12 |
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Hi and thank you for info! Did this happen when the boat was new?
In my boat this starts after 3-4 years!
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Hanse 400#655
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StavrosNZ
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Joined: 24 October 2014 Location: New Zealand Status: Offline Points: 581 |
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Posted: 27 October 2015 at 23:34 |
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I am second owner, the first mentioned he replaced sail drive anode 3-4 times per year, paid a diver to check it.
I investigated and resolved the issue.
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Stephen
2010 H400 #691, Auckland, New Zealand |
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SausalitoDave
Commadore 
Joined: 13 October 2014 Location: Sausalito Status: Offline Points: 366 |
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Posted: 28 October 2015 at 03:26 |
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The white plastic rings are - I am almost certain - thrust washers. They are not there as any from of isolation.
Dave Hanse 505
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alidal
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Joined: 30 September 2010 Location: Norway Status: Offline Points: 297 |
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Posted: 28 October 2015 at 15:45 |
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What is very strange is that I got this problems after 3-4 years!
It also have to be something else...... My neighbour boat is an older wooden fishingboat and this started when he came there. I have now moved my bot to another place to see if the corrosion (it started again a few weeks ago) I now have the new SD60 drive and it is the alu anode on the drive that is corroded now My old corroded drive: http://www.myhanse.com/galvanic-corrosion-hanse-370_topic5283_post72722.html#72722
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Hanse 400#655
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High Time
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Joined: 04 September 2012 Location: Portsmouth UK Status: Offline Points: 819 |
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Posted: 28 October 2015 at 18:58 |
Those pictures of the old corroded saildrive are horrendous! Did you discover the reason for the corrosion? I would be very nervous about fitting a new saildrive unless I had found the problem and eliminated it. Did anything electrical change on your boat or on your neighbours' boats during the year when this happened? Do you leave shore power connected to your boat for long periods? If so, do you know what the earthing arrangements are for the shore power? Are any of your neighbours' boats on a different (electrical) phase? If you don't know the answers to the last couple of questions I suggest you get the marina involved - losing a complete saildrive through galvanic or electrolytic corrosion is very serious.
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Roger
High Time (415 #038) |
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alidal wrote: