Trouble With the Cape Horn Windvane

[John Stone]

For those that sail singlehanded, especially offshore, you know the critical importance of a windvane (or reliable auto pilot if you are if that persuasion). Without it you are in a very bad situation. My Cape Horn Windvane has been a workhorse for me for nearly 10,000 miles of mostly offshore sailing. Until now.

This problem started on the way home from my last voyage to the Virgin Islands in June 2019. I had a lot of trouble with the servo blade disconnecting due to all the sargasso weed we encountered. When I got home I mailed the servo blade and lower stock to have the disconnect notches deepened. As always Cape Horn did a quick turn around. By then I was deep into the engine installation. So I couldn't test it.

Flash forward, I launched the boat in May this year and by the time I was able to get some meaningful sailing in it was apparent there was a problem with the vane. It was not steering reliably. The airblade was not responding to the wind shifts. I shot some video and sent it off for Cape Horn's assessment. We hauled the boat a couple weeks later for two months.

We relaunched about a week ago and immediately began preparations for our voyage back to the West Indies. In the meantime I had brought the vane home while the boat was on the hard and looked it over closely. Yves Gelanas, the designer and builder, corresponded with me and we deduced the airblade and servo blade (the wood paddle that goes into the water, was out of alignment. Probably as a result of work they had performed in the servo blade. So, Gayle and I took the boat out the other day and aligned it. But it was still not functioning properly. I shot more video and sent it off to Yves. The situation was dire. We had provisioned the boat and I am in process of loading my tools and gear. No vane--no voyage. Simple as that.

I brought the vane home yesterday and decided there was no other choice but to take the vane completely apart. Yves had discouraged me from doing so because operational checks indicated the tolerances for the components were fine. But I saw no other option. I had to eliminate every possible problem.

I know the concept of how the vane works. But I did not know how it's components interacted. Wow. What a simple system. Beautifully engineered. I had it stripped apart like an M4 in about 30 minutes. It was in perfect shape. I put it back together this morning. By then Yves had seen the latest video. I mentioned that it seemed the servo was pivoting on its own and not as a result of the air blade. He told me to check the servo blade and look down it's length and see if it was warped. Bingo--that appears to be the source of the problem. The blade was warped along its length, out of true about 1/4". Our thinking is it is getting lift to starboard and in light air pivoting on its own. Because the problem is most obvious in light air and water is 250 times more dense than air the airblade can overcome the servo blade.

So, tonight I used a straight edge to determine the location of the warp and how to address it. I used a block plane, a jack plane, and a long board to smooth and straighten out the blade. It took about two hours of careful work. It's foil shaped so I had to go slow and constantly check the shape. I think I have it pretty close. I didn't want to get too aggressive. When I am working on a project I tried to remember the first rule--Do no harm.

I won't know how it works till we go for a sail. But I have a good feeling about it. All the symptoms point to the servo blade. Hopefully, it will work like it's old self and I can sail with confidence that my windvane will steer as accurately and reliable as it has in the past

[John Stone]

The after pictures. Slow careful work. I am eager to see how it works.

[Steve Laume]

As much as I love wood, it seems like it was a poor choice of materials for that application. Since you spent the time to true it up, I would be encapsulating it with epoxy. Maybe add a couple of layers of glass, for good measure. If a slight warp is all it takes to make the thing non functional a spare might also be worthy of your time.

Where will you be cruising this winter?

I might see you there, Steve.

[wikakaru]

It makes perfect sense when you explain it, John, but I don't think I would have figured that out by myself in a million years. I'm looking forward to your report on the results of the repairs and, assuming they are effective, to your account of your voyage.

Smooth sailing,

Jim

[John Stone]

As much as I love wood, it seems like it was a poor choice of materials for that application. Since you spent the time to true it up, I would be encapsulating it with epoxy. Maybe add a couple of layers of glass, for good measure. If a slight warp is all it takes to make the thing non functional a spare might also be worthy of your time.

Where will you be cruising this winter?

I might see you there, Steve.

I have had the same thoughts....

[John Stone]

It makes perfect sense when you explain it, John, but I don't think I would have figured that out by myself in a million years. I'm looking forward to your report on the results of the repairs and, assuming they are effective, to your account of your voyage.

Smooth sailing,

Jim

Thanks Jim. I am equally interested to see how it works out.

[Jim Walsh]

Nice detective work and problem solving. I fully agree with Steve’s suggestion to improve the component by encapsulating it in a thin layer of glass.
This year the sargasso weed wasn’t too bad, I only had to use a boat hook to clear my watervane once or twice. I tried putting a couple coats of wax on it before I left, it may have been helpful. It’s stainless so it’s pretty slippery as is.

[John Stone]

Nice detective work and problem solving. I fully agree with Steve’s suggestion to improve the component by encapsulating it in a thin layer of glass.
This year the sargasso weed wasn’t too bad, I only had to use a boat hook to clear my watervane once or twice. I tried putting a couple coats of wax on it before I left, it may have been helpful. It’s stainless so it’s pretty slippery as is.

I am unsure about the solution. Though I've considered it, I'm skeptical of cloth and epoxy over wood immersed in water. Seems water will eventually find its way in there and then it can't get out. Will it work. Maybe. Probably. Not sure. I've put the question to Yves but have not had a reply in that topic yet.

Regardless, I don't have time for a modification before I sail. So it's something I'll have to think about. Not sure if this is a common problem. Seems I would know about it, though I confess it seems like it would naturally be an issue--long slender bare wood in and out of the water, in the sun and shade, changing temps. IDK.

Seems a composite blade would be advantageous. But it would be expensive to make. Perhaps other alternatives. In the meantime, before I start investing energy in a modification I need to be sure I have fixed the problem. Loading tools today. Still have to climb the rig and inspect carefully. Kids coming home from college for Thanksgiving. Got competing demands. Good wx window on Thanksgiving through Sat. Probably not viable. I keep hearing that old axiom "Wind and tide waits for no man."

[Jim Walsh]

Nice detective work and problem solving. I fully agree with Steve’s suggestion to improve the component by encapsulating it in a thin layer of glass.
This year the sargasso weed wasn’t too bad, I only had to use a boat hook to clear my watervane once or twice. I tried putting a couple coats of wax on it before I left, it may have been helpful. It’s stainless so it’s pretty slippery as is.

I am unsure about the solution. Though I've considered it, I'm skeptical of cloth and epoxy over wood immersed in water. Seems water will eventually find its way in there and then it can't get out. Will it work. Maybe. Probably. Not sure. I've put the question to Yves but have not had a reply in that topic yet.

Regardless, I don't have time for a modification before I sail. So it's something I'll have to think about. Not sure if this is a common problem. Seems I would know about it, though I confess it seems like it would naturally be an issue--long slender bare wood in and out of the water, in the sun and shade, changing temps. IDK.

Seems a composite blade would be advantageous. But it would be expensive to make. Perhaps other alternatives. In the meantime, before I start investing energy in a modification I need to be sure I have fixed the problem. Loading tools today. Still have to climb the rig and inspect carefully. Kids coming home from college for Thanksgiving. Got competing demands. Good wx window on Thanksgiving through Sat. Probably not viable. I keep hearing that old axiom "Wind and tide waits for no man."

Perhaps a blade laminated out of scraps and sealed with epoxy would be resistant to warping….and keep the original as a spare?

[John Stone]

Nice detective work and problem solving. I fully agree with Steve’s suggestion to improve the component by encapsulating it in a thin layer of glass.
This year the sargasso weed wasn’t too bad, I only had to use a boat hook to clear my watervane once or twice. I tried putting a couple coats of wax on it before I left, it may have been helpful. It’s stainless so it’s pretty slippery as is.

I am unsure about the solution. Though I've considered it, I'm skeptical of cloth and epoxy over wood immersed in water. Seems water will eventually find its way in there and then it can't get out. Will it work. Maybe. Probably. Not sure. I've put the question to Yves but have not had a reply in that topic yet.

Regardless, I don't have time for a modification before I sail. So it's something I'll have to think about. Not sure if this is a common problem. Seems I would know about it, though I confess it seems like it would naturally be an issue--long slender bare wood in and out of the water, in the sun and shade, changing temps. IDK.

Seems a composite blade would be advantageous. But it would be expensive to make. Perhaps other alternatives. In the meantime, before I start investing energy in a modification I need to be sure I have fixed the problem. Loading tools today. Still have to climb the rig and inspect carefully. Kids coming home from college for Thanksgiving. Got competing demands. Good wx window on Thanksgiving through Sat. Probably not viable. I keep hearing that old axiom "Wind and tide waits for no man."

Perhaps a blade laminated out of scraps and sealed with epoxy would be resistant to warping….and keep the original as a spare?

That's a good idea. A laminated one would be less likely to warp. Yves said they used to make them out of composite material as an option but they had few buyers interested. He said it was expensive to make so they went back to teak. He offered to give me the one off Jean du Sud but it's too small for my boat. Also he was about to ship me a new teak one at the end of the week but I'll be at sea by the time it arrives I think. So I asked him to hold off. If I planed this one correctly it should work and we can figure out the way forward from there. They have always taken care of me and they stand behind everything they make so it's going to work out.

[gonesail]

I inherited a cape horn autopilot from the previous owner of my boat .. and the blade is indeed a white plastic composite.

[John Stone]

I inherited a cape horn autopilot from the previous owner of my boat .. and the blade is indeed a white plastic composite.

That's a great piece of equipment. Not an auto pilot. It's a self steering windvane. So, not really an auto pilot. Though I think it's better than an auto pilot.

Is it installed? Ever use it? Should not be a plastic blade. Should be composite fiberglass if made by Cape Horn. If indeed it's plastic then perhaps it was made by the PO?

You're a lucky man.

[John Stone]

I heard back from Cape Horn regarding protective coating for the teak servo blade. They use Cetol. Interesting. Never would have thought of that. Too late for me at this point. I slathered on a bunch of Interlux teak oil the day before I heard back. I'll worry about it later. The important thing right now is to see if my mods addressed the problem.

They also have a just built servo blade ready to ship to me if I need it. Let's hope I don't.

[John Stone]

We took the boat out for a sail in some very light wind yesterday afternoon. No clouds. Blue sky. Low angle sunlight. About 47° F. Wind about 4-6 knots. Perfect conditions for testing my tune-up on Cape Horn Windvane. Of course, now that I trued the servo blade flat I had to realign the the air blade with the servo. We did it underway. I don't have a stern pulpit which makes it so much easier to hang over the fantail...but it's like a circus act too because you can just slip right off the back of the boat when you are proned out over the sternwith the upper part of your body hanging down working on the vane.

To prevent the unthinkable from happening Gayle grabbed hold of my belt and sat on my legs. Hilarious. I'm thankful there are no pictures! Anyway it left both my hands free to make the adjustments to the mechanism contained in the junction of the horizontal tube passing through the transom snd the vertical tower.

With the adjustments made the boat steered well. Pretty much ghosting conditions. We hoisted the big jib withe it's zip-on bonnet and a full main. Mostly we made about 2 kts but hit a whopping 3 knots for a while. Actually, I love that kind of sailing. Water burbling along the hull and a light breeze over the deck.

So I am declaring victory. I did decide to purchase a second servo blade. It comes with a SS head attachment so it's a complete replacement if anything happens to my primary blade. Probably a good thing to have considering my potential voyaging plans.

The boat is nearly fully loaded. The horizon beckons...

[wikakaru]

With the adjustments made the boat steered well. Pretty much ghosting conditions. We hoisted the big jib withe it's zip-on bonnet and a full main. Mostly we made about 2 kts but hit a whopping 3 knots for a while. Actually, I love that kind of sailing. Water burbling along the hull and a light breeze over the deck.

So I am declaring victory. I did decide to purchase a second servo blade. It comes with a SS head attachment so it's a complete replacement if anything happens to my primary blade. Probably a good thing to have considering my potential voyaging plans.

The boat is nearly fully loaded. The horizon beckons...

Good job, John! Sailing in light conditions is usually the hardest thing for self-steering gear to do, so it sounds like you have it fixed.

I have been wondering if you could de-couple the servo paddle from the wind vane for testing to see if the paddle tries to steer itself one way or another with no external wind input. Maybe it would just be as simple as removing the wind paddle from the top of the gear and holding the wind paddle counterweights in place with a line or bungee so waves/heeling/rolling don't cause input. If you could measure how much deflection force you get from a zero-input servo paddle at a particular boat speed (for example using a fishing scale), you could tell if the force from the mis-shaped paddle changes in the future as water soaks into the newly exposed wood grain and re-bends the paddle.

Or you could just go sailing and not worry about it.

Does this mean your cruise is a go?

Smooth sailing,

Jim