Hi, everyone.
We just hauled out and dropped the rudder. When we turned it upside down, all this black water poured out. yech!
The rudder tube on an MK1 is hollow and stainless steel, so that means that standing water (and it could be fresh rainwater or saltwater but either way it will be anaerobic) will sit at the base of the rudder tube for YEARS! Not a good design, unless I'm missing something.
So we are thinking about filling the rudder tube with something waterproof - epoxy? closed-cell foam? or ?
Thoughts on that?
Taking the opposite tack, I'm thinking about drilling drain holes at the base of the rudder based on my reading of books which say that flowing (oxygenated or aerobic) salt water will not corrode stainless steel. A possible negative consequence of this would be that the rudder tube might be weakened at its base which is a high-torque area.
Thoughts on that?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
I wondered about this water too. Assuming it comes into the top of the pipe, I made a clear cover (velcro to hold it on) to stop water entering the top maybe via the bolt holes? I also sealed around the top of the rudder stock where it enters the fiberglass but I don't have a lot of confidence in this.
Otherwise I think the bottom of the tube is sealed.
I am considering having the stock x-rayed for possible crevice corrosion, has anyone done this?
S.V. Wind Star
Rob & Margie Kyles: Auckland ,New Zealand
Mk I Hull #105 1983 Std Rig, Std Keel
Good idea about x-raying, Rob. I'll look into that next haulout. This time, what we did is custom-machined an inner stainless steel tube to fit snugly into the existing outer stainless steel tube. Tapped that into place - way down deep into the rudder inside the outer one. That way if the outer tube cracks, there is still the new inner tube to take the load.
Next time I will probably also fill it all with closed cell foam to waterproof the inner tube (hopefully).
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
What would stop the new inner from rotating in the event the old tube fractures all round ie how is the new inner fixed in place?
Duncan McNeill
1984 Catalina 36 #178
standard rig fin keel M25
Channel Islands
Hi, Duncan. Good question.
The inner post is press-fit in. I think the friction will hold it in place. Also the through bolt which holds the steering harness passes through both tubes now. .
The potential problem, of course, is the lower part of the two tubes, where they are both inside the rudder. I can't think of any way to lock them together down there below where the break point would be, not without drilling a hole in the rudder, and that comes with its own set of new problems, yes?
I'm kinda counting on the outer tube not breaking all the way around, and if it does, while it may not be enough friction to steer with, I'm thinking that the press-fit friction will at least keep the rudder from falling off altogether. That would give me a chance to bring the rudder topside, drill a hole through the rudder, and both tubes, and install a through-bolt through both sides of the rudder as a temp fix...assuming I'm not in a storm when it all happens :-)
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Talking to the installer, a bit more useful info on this fix:
There is a welded vertical seam on the inside of the original outer tube from where it was originally welded (or at least there is on my boat's rudder). He had to machine-cut a ledge along the entire length of the new inner tube to accommodate that, i.e. so that the new inner tube would press all the way into the rudder (to the level of the original outer tube). That is an important piece of info for anyone trying to do the same thing, since the weld acts like a shaft key. It also means that the inner tube can not rotate or spin, even if the outer tube corrodes and breaks around its entire circumference.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Hi Ben
I intend doing this fix for our boat, have you a record of the size of pipe you used to put down inside the rudder shaft? Unfortunately I won't be able to measure ours for many months, and it would be good to know the size of pipe required before then.
Regards
Rob
S.V. Wind Star
Rob & Margie Kyles: Auckland ,New Zealand
Mk I Hull #105 1983 Std Rig, Std Keel
Hi, Rob.
We believe it was a 2" inside diameter stainless steel pipe. Since it matters more, we are clearer on the outside diameter of it, which was 2.375" (which is the inside diameter of my original rudder post). However, it needed a lot of machining to get it to fit though and the inside weld of the original post. This meant that a table top notch had to be put down the the length of the new post. This notch was roughly an 1/8" of an inch wide.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Brilliant, that's exactly what I need to know. Hope it works well for you :-) Thanks.
S.V. Wind Star
Rob & Margie Kyles: Auckland ,New Zealand
Mk I Hull #105 1983 Std Rig, Std Keel