1982 Skye 51
Join Date: May 2008
Location: Somewhere between NZ and the Chesapeake Bay
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Skeg-hung Rudder Question
I have a full skeg-hung rudder and recently I noticed a problem that dates back to 1982 when the boat was built. I pulled the rudder in 2008 and completely rebuilt it when I noticed a bit of water had penetrated where the fiberglass attaches to the rudder stock. I did the removal and reinstall myself but this problem never showed itself.
It seems that the threads on the rudder stock for the two top retaining nuts and the threads on the nuts themselves are different threads. There are two nuts at the top that are tightened on each other and then a set screw goes through the top nut and wedges against the bottom nut to lock them in place. The static arrangement rides on delrin bearings atop a large bronze bearing/sleeve. Two feet below that is the stuffing box assembly, and then a large bronze gudgeon at the bottom of the skeg.
The problem came to light on my way from Cocos Keeling to Rodrigues when I heard a loud thud from the compartment where the nuts are exposed and you would install the emergency tiller. When I looked in, I noticed the nuts were loose. It was a bit alarming but I tightened them back down only to have the same problem a couple days later. When I arrived at Rodrigues, I pulled both nuts of and, just out of curiosity, got out my thread gauges. To my surprise, they are different threads than the male threads on the rudder stock! After 33 years, almost 100,000nm, and once dropping the rudder, this finally came to light. After a little tinkering, I found that if the threads are aligned just right, they will grab well and stay put. However, just a fraction of a turn in either direction causes them to jump up one thread. I must have set it just right on the reinstall in 2008. The thunk I heard was this jumping threads.
Now Iím in Madagascar but heading for South Africa where I will have the proper nuts machinedóitís 3.5Ē solid stainless stock so Iím guessing I will have to have some fabricated. My question is: just how much of the weight of the rudder should be resting on the gudgeon and how much taken by the nuts/top bearing? 100%, 90%, 75%Ö? Right now, it is secure and wonít fall out of the boat but most, if not all, the weight is on the gudgeon and Iím worrying about wearing the glass out down there as the rudder turns back and forth.
I have not had a very reliable internet connection, so have not been able to research this very thoroughly but I thought I would put it out here and see what advice or opinion is out there. Any input is much appreciated. Thanks.
"The notion of life implies a certain absoluteness of self-enjoyment." -Alfred North Whitehead
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