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| S&S Swan Maintenance - Checking the rudder |
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Join Date: 02 February 2007
Posts: 202 |
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Checking the rudder Dear professor, dear all, We very unfortunately missed the rendez-vous in Elba as our dear Soeur Anne (41/022) was still drying for osmosis treatment. Now it is almost finished (and looks beautiful) but we want to take this opportunity to check the rudder for corrosion, mainly the fixation of the pair of plates holding the rudder on the axle of the rudder. Is this being done through riveted keys or through welding? Is there a real risk of corrosion? If this is the case I understand it is not necessary to bring the whole rudder down but only to take off the U shaped stainless steel sheet in front the rudder (beeing fully turned on one side). In our case to do this we must cut the lower part as it covers the bottom articulation. Is this correct? See picture below. Many thanks for your help, and kind regards. Philippe Vidal (per Matteo recommendation I fully agree with!)
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Join Date: 02 January 2008
Posts: 1547 |
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Dear Philippe The plates holding the rudder blade are welded to round bosses, and the bosses are hot shrunk onto the stock with a key securing the joint. If there is corrosion you should be able to see it through the open slots, and there would also be visible rust weeping down along the stock. Check the welds between the plates and the bosses for cracks, and that the bosses are tight on the stock. If they are not, there will be play in the rudder stock, i.e. the stock can turn slightly without the blade moving. I believe you can see enough through the slots, and it is not necessary to remove the U-shaped fairing piece. If you prefer to remove it I think it comes off in one piece if you first pull the top out to one side, and then lift the piece vertically to release the lower end Best regards Lars |
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Join Date: 02 February 2007
Posts: 202 |
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Dear professor, We finally took off the U shaped fairing after cutting a small bit which will be welded back tomorrow. The picture below shows what we saw after a little bit of cleaning with acid. It is just as new, incredible. I was astounded! Now, one can see what a Swan is made of. Congratulations, and many thanks for your invaluable help. Kind regards. Philippe.  |
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Join Date: 02 January 2008
Posts: 1547 |
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Dear Philippe Pls note that when stainless that will be in the water is welded precautions must be taken to avoid weld decay, or with a technical name, carbide precipitation. Otherwise there will be severe corrosion Lars |
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Join Date: 02 February 2007
Posts: 202 |
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Dear professor, Thank you very much but... I am afraid the welding has already been done, and I am not sure which precautions have been taken. When corrosion takes place I suppose that it will be visible from rust weeping at the bottom of the fairing, is that right? Or will it just be the fairing "dissolving" in the water? If the damaged part of the fairing is to be suppressed, how far from the weld should it be? Is there any risk of that corrosion spreading to other parts of the rudder? Sorry for all these questions, but I am quite frustrated by this error, especially since the rest of the rudder is in perfect condition. Many thanks for all this information. Best regards. Philippe.
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Join Date: 02 January 2008
Posts: 1547 |
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Dear Philippe As the fairing is not a structural part it is suggested that you wait and see. If there are corrosion problems the weld will suffer, not other parts. A new piece of stainless can then be welded in, make sure that the welder knows his trade. Kind regards Lars |
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