Here is another link to a rudder removal by Matt Cawthorne that is very good. It was very helpful to me before I removed, repaired, and reinstalled the rudder on the Far Reach. I just checked the link and it’s still good.
http://www.cawthorne.org/Rudder.html
Rudder Removal CD33
Moderator: bobdugan
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John Stone
- Posts: 3562
- Joined: Oct 6th, '08, 07:30
- Location: S/V Far Reach: CD 36 #61 www.farreachvoayges.net www.farreachvoyages.com
Re: Rudder Removal CD33
Last edited by John Stone on Dec 8th, '17, 00:18, edited 1 time in total.
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Matt Cawthorne
- Posts: 355
- Joined: Mar 2nd, '05, 17:33
- Location: CD 36, 1982
Hull # 79
Re: Rudder Removal CD33
Take a look at the second picture posted by Zieda. There is very significant crevice corrosion happening in that rudder shaft. Crevice corrosion is problematic due to the way that it may only be visible as a tiny dot or what appears to be a small black line on the surface. what is underneath can be a cavern that is of significant size. I recommend that you open up any crevice corrosion and clean it out down to clean metal, following all 'leads'. If the shaft is compromised consider replacement. This is not a problem that is limited to Cape Dories. I have seen it on many boats.
I just replaced my rudder this past year, with a new shaft because of signs of crevice corrosion. I built the core with syntactic foam (that is a fancy way of saying microbaloons, short fibers and resin) instead of urethane or pvc foam as it is way tougher and transmits moisture at a much lower rate (and is way more expensive).
If you are going to use stainless steel as a rudder shaft, make sure that it is passivated (the iron is removed from the surface layer). Without that it is more prone to crevice corrosion. Passivation usually involves dipping the shaft in hot nitric acid or hot citric acid for a specific length of time. Of course if they scratch it during rudder manufacture, it needs to be re-passivated before being cast into the rudder. If the shop making the rudder does not know what passivation is, or tries to talk you out of it then go somewhere else. If you do elect to re-use your rudder shaft, make certain that there are no crevice corrosion sites still in place, inspect with dye pennetrant or mag particle and re-passivate.
Regards,
Matt
I just replaced my rudder this past year, with a new shaft because of signs of crevice corrosion. I built the core with syntactic foam (that is a fancy way of saying microbaloons, short fibers and resin) instead of urethane or pvc foam as it is way tougher and transmits moisture at a much lower rate (and is way more expensive).
If you are going to use stainless steel as a rudder shaft, make sure that it is passivated (the iron is removed from the surface layer). Without that it is more prone to crevice corrosion. Passivation usually involves dipping the shaft in hot nitric acid or hot citric acid for a specific length of time. Of course if they scratch it during rudder manufacture, it needs to be re-passivated before being cast into the rudder. If the shop making the rudder does not know what passivation is, or tries to talk you out of it then go somewhere else. If you do elect to re-use your rudder shaft, make certain that there are no crevice corrosion sites still in place, inspect with dye pennetrant or mag particle and re-passivate.
Regards,
Matt