Monitor Wind Vane Rudder Broke Off

[seandepagnier]

My monitor wind vane steering rudder broke off and unfortunately I was unable to retrieve it. It was one of the early monitors (serial #432) and stainless continuously submerged isn't great, it just failed from stress corrosion.

I have used sheet to tiller steering to reach the next port, but I am about 25% (1 knot) slower on average using this method and it's also harder on the sails.

There are no boats with monitor vanes here.

Could someone please give me the exact dimensions (height width and thickness) of the rudder so I can build an identical one. Suggestions for how to do this would be helpful as well.

I am thinking to take a galvanized steel pipe as a shaft, then put over it plywood ribs cut to the foil shape using a jig saw. Next I can wrap this with glass and epoxy resin. Is there an easier way? What is a good way to prevent the paddle from rotating around the pipe?

I would rather use iron wood or ebony than galvanized steel to avoid rust, but apparently I need to go to congo to find it.

Maybe I can encapsulate the galvanized pipe completely using fibreglass and epoxy?

[unclemack]

Saw a 1995 Scanmar promo on youtube said they kept records of individual boats' installations right back to the earliest ones.

Maybe selfsteer still has those records?

Don't know any more about that company myself, sorry.

Hope somebody can help out, good luck with it.

[exMaggieDrum]

We had an older Monitor years ago. I would recommend you carefully inspect all the tubing and welds on all parts of what you have left. They are very susceptible to cracking and failure. Your rudder falling off may be a symptom of overall deterioration. We had to trash ours in the end. Considering where you are at you may not have any choices, or a budget for a new one. Good luck.

[seandepagnier]

In indonesia I found someone who could reweld it for $1 per weld, and so I don't have any cracked welds to worry about. I also replaced plastic bearings. I can't believe you would scrap the entire thing as it can probably be repaired or at least used for parts.

The pipe that failed is the one going to the oar where it was continuously submerged for very long periods of time and also has the most stress of anywhere on the entire wind vane. It's just too bad there isn't a safety line inside the pipe to save the oar... if I had known about this potential problem I would have installed one.

[Paul Elliott]

It's just too bad there isn't a safety line inside the pipe to save the oar... if I had known about this potential problem I would have installed one.

Sorry, I can't help with your problem, but there *is* a safety line that is normally attached to the rudder and runs up externally to a secure point on the boat. This is your retrieval line, used when you are pulling the oar out of the water. The retrieval line also keeps you from losing the oar should the sacrificial connecting-tube part of the rudder assembly break when you hit something (for example).

This retrieval / safety line has saved my oar on a few occasions. I carry spare connecting tubes and hardware.

[UNCIVILIZED]

Originally Posted by boat_alexandra

My monitor wind vane steering rudder broke off and unfortunately I was unable to retrieve it. It was one of the early monitors (serial #432) and stainless continuously submerged isn't great, it just failed from stress corrosion.

I have used sheet to tiller steering to reach the next port, but I am about 25% (1 knot) slower on average using this method and it's also harder on the sails.
Well, at least your arrangement worked. Hand steering for that length of time would about kill anyone.

There are no boats with monitor vanes here.

Could someone please give me the exact dimensions (height width and thickness) of the rudder so I can build an identical one. Suggestions for how to do this would be helpful as well.
There are a lot of tips & stories, regarding building rudders on here, if you do a search. And also view Nicholson58's photo album, as well as perhaps querying him.
But it's pics will help you some with my description to follow.

I am thinking to take a galvanized steel pipe as a shaft, then put over it plywood ribs cut to the foil shape using a jig saw. Next I can wrap this with glass and epoxy resin. Is there an easier way? What is a good way to prevent the paddle from rotating around the pipe?
On this, go to www.WestSystem.com & look up bonding to steel. As probably your best bet will be to grind off all of the galvanizing on the pipe where the rudder will be, & bonding on several layers of fiberglass with epoxy, as your first step.

You'll want the shaft to look something like this Nice Job of Shaft Roughening | Multihull Design Blog prior to bonding/your final pre-bonding, sanding step.

And for that final bit of sanding, prior to wrapping the shaft with glass. You'll be sanding the shaft while both it, & the sandpaper are coated with wet epoxy.
That way, the epoxy is bonding to a fresh, 100% non-oxidized layer of metal. And the epoxy keeps any moisture in the air out as it cures, so long as you glass things early eough in the day, to prevent condensation from forming on anything.

And as things cure, the epoxy shrinks a fraction of a percent, so in addition to being chemically bonded into place. It's also mechanically keyed into the surface of the shaft.

For your foil sections (or guides), you can go online, & download some NACA ones, if you can't get the proper ones from your vane's maker, or here on the forum.
There's a bit of a guide to such here Rudder stalling AOA....... - Fix It Anarchy - Sailing Anarchy Forums

So once you have your foil sections, print them out, & glue the templates to some pre-epoxy soaked, & fiberglassed plywood. And drill them for their shaft holes, prior to cutting them out.
Note: remember to subtract the rudder's skin thickness from the final dimensions of the foil section templates. When cutting out the pieces which will actually go onto the rudder.
From there, after your foil shapes are sealed up properly, you simply bond them well (as in substantially) onto your pre-glassed shaft. While making sure to keep them properly lined up.

And then, you can fill in the area in between them, with; foam, wood, etc. Followed by glassing over the whole thing. Fairing it as much or as little as you like. But do fair & template it some, so that you have a proper foil section/shape.

Also, if you want to, you could probably use wood, for the rudder's skins. Assuming that it's bonded to the core of the rudder & the foil stations (of course). Plus, again, deduct for your skin thickness when cutting out your templates, above.
The wood can be either very thin plywood, strips of same, or strips of solid wood, or a combination of both.

I would rather use iron wood or ebony than galvanized steel to avoid rust, but apparently I need to go to congo to find it.

You might, maybe, be able to get away with a composite shaft. Or a wood/composite hybrid. Especially if you have some higher modulus fibers onboard, or some Unidirectional glass. Of which, you can more or less, make the latter (from standard glass, or axials).

I say might, as I don't recall what kind of loads the shaft on one of those rudder's sees. But I doubt that they're low, so...
Plus, composites are Much more sensitive to both point, & shock loadings. Which I know such a rudder & it's shaft see plenty of.
The point loading being where it'd meet up with/slip into the stainless section. And assuming that that part of the vane is stainless, it'll kind of act as a guotinne when constantly pressed against softer materials. Like wood, & composites.

Maybe I can encapsulate the galvanized pipe completely using fibreglass and epoxy?

Again though, as stated, there's info on all off this, & full on rudder construction at the WEST System sight. Both in their free for download, book on boatbuilding, in their downloadable product user guides, & also by doing a search on their site for rudder builds, & rudder rebuilds.

Plus, they have a sub-website, called www.EpoxyWorks.com wherein, all manner of projects are described. Including a rudder rebuild in the Winter '04 edition.

And of course, there's plenty of info out there, Online, & likely on YouTube, on the topic as well.
Speaking of which, you might do a search for the schematics & blueprints off your vane online, when looking for your foil section.

But if you truly come up short; fat foils stall much less easily, & are more forgiving when they do. So with that, & a ballpark idea of the size & shape of your previous rudder, you'll be able to come up with something.

PS: If the whole foil section thing is just too much, or complex, for whatever reason, consider this. --> There are plenty of boats out there with 0 foil section to their rudders. Ditto on many centerboards & keels.
As a square plate, actually has better lift characteristics than many of the crap foil sections out there. Or even poorly executed, great foil shapes.
AKA don't lose your mind over it.

[Sailormantx]

Use your safety line! See the monitor manual, available online from selfsteer.com. The tune connecting the water paddle to the shaft is a safety tube, designed to break if it hits something in the water to prevent damage to the windvane. I have seen functional home made paddles used successfully where it was impossible to get a replacement from Scanmar. I will get measurements for you later this afternoon, the only thing I remember offhand is that the safety tube is 1.5 inches OD and 14 inches long for my vane.

Sent from my K013 using Cruisers Sailing Forum mobile app

[Orion Jim]

Originally Posted by boat_alexandra

My monitor wind vane steering rudder broke off and unfortunately I was unable to retrieve it. It was one of the early monitors (serial #432) and stainless continuously submerged isn't great, it just failed from stress corrosion.

I have used sheet to tiller steering to reach the next port, but I am about 25% (1 knot) slower on average using this method and it's also harder on the sails.

There are no boats with monitor vanes here.

Could someone please give me the exact dimensions (height width and thickness) of the rudder so I can build an identical one. Suggestions for how to do this would be helpful as well.

I am thinking to take a galvanized steel pipe as a shaft, then put over it plywood ribs cut to the foil shape using a jig saw. Next I can wrap this with glass and epoxy resin. Is there an easier way? What is a good way to prevent the paddle from rotating around the pipe?

I would rather use iron wood or ebony than galvanized steel to avoid rust, but apparently I need to go to congo to find it.

Maybe I can encapsulate the galvanized pipe completely using fibreglass and epoxy?

http://www.selfsteer.com/products/monitor/index.php

Scanmar can provide any spare part you require. Give them a call or email them. You can also download the owners manual so you will know how to maintain and operate your unit in the future. If you replace an old unit with a new unit they also offer a trade-in allowance.....and it is substantial. I know, that is what I did last year. I don't spare expense when my life can depend on it. Good luck

[UNCIVILIZED]

]

Originally Posted by boat_alexandra

Could someone please give me the exact dimensions (height width and thickness) of the rudder so I can build an identical one. Suggestions for how to do this would be helpful as well.

I am thinking to take a galvanized steel pipe as a shaft, then put over it plywood ribs cut to the foil shape using a jig saw. Next I can wrap this with glass and epoxy resin. Is there an easier way? What is a good way to prevent the paddle from rotating around the pipe?

Maybe I can encapsulate the galvanized pipe completely using fibreglass and epoxy?

There are perhaps a couple of “easier” ways to build a rudder for your vane. Them being pretty much offshoots of one other theme.

You’d bond a glass sleeve onto the shaft, as detailed before. And then, to it’s centerline, along it’s trailing edge, bond a sheet of plywood, or DIY thin sheet of reinforced wood (see below). And this will act as the spine for the rudder’s blade.

You’d do it using strips of glass going from one side of the sheet of wood, around the rudder sleeve, to the other side of the sheet of wood. Repeating this several times, so that the fiberglass extends a little bit further aft on the wood each time.
And once it’s solidly bonded to the shaft, so that the glass is sufficiently thick to resist the torsional forces within the rudder. Then seal the rest of said piece of wood.

After that, epoxy some any of the following to that center spine piece; thin sheets of plywood, strips of milled to size (regular) lumber, sheets of foam (or balsa).
Progressively sealing each piece as you go, & using epoxy & glass in order to create as much of a monocoque structure as you can.

Then plane or sand this built up blade into a foil section. Seal it up with a few layers of glass & epoxy. And template & fair it to shape.

There would perhaps be a bit more sanding, but you wouldn’t have to deal with filling a blade in between foil sections bonded to the shaft.


--> As to the DIY sheet of thin, reinforced wood, referenced above. You’d need to have a flat, smooth worktop, with some kind of “mold release”. Be it a well waxed sheet of Formica or Melamine, some Visquine sheet plastic (or a trash bag), or even some overlapping strips of packing or duct tape.

Then you’d take a thick piece of solid lumber, & slice off a bunch of thin strips. Perhaps 1/4” (6mm) – 3/8” (10mm) thick. And glue their edges together on the worktop, with each piece placed such that the opposite side as compared to the one nest to it, is facing upwards. So that there's a natural balancing out of the wood grain's bias.
Meaning that you're doing it to minimize the natural tendency for your flat piece to want to warp, or cup, in one direction.

And after that, simply sand/plane both sides of the wood to form a smooth, flat surface. And add a couple of layers of glass & epoxy to each side.


PS: BTW, in the long run, a stainless pipe section would be preferable to mild steel (and Titanium would be one notch better yet, given the right alloy), but again, that's in the long run.
Although, obviously, you want to coat as much of the pipe as possible. With paint, or any other corrosion preventative.

Also, the rudder shaft's weak point will be the seal at the top of th fiberglass. So some folks will bond the top 1/2" or so of the fiberglass to the shaft using a flexible adhesive, like 5200. With the lower section of the same piece of glass being bonded to the shaft with epoxy.

[seandepagnier]

First of all, thanks for the replies.

I am still looking for exact measurements of the oar to be sure, and importantly, the exact position of the pipe to ensure it is properly balanced.

Originally Posted by Paul Elliott

Sorry, I can't help with your problem, but there *is* a safety line that is normally attached to the rudder and runs up externally to a secure point on the boat. This is your retrieval line, used when you are pulling the oar out of the water. The retrieval line also keeps you from losing the oar should the sacrificial connecting-tube part of the rudder assembly break when you hit something (for example).

This retrieval / safety line has saved my oar on a few occasions. I carry spare connecting tubes and hardware.

I had this safety line attached to the oar at the top tied tight so the oar could not slip away (because of the bolt) and it had saved the oar in the indian ocean when the pin (that the oar rotates around when it's lifted) fell away and I used a bolt instead.

I would have needed to attach the safety line to the hole at the bottom of the rudder... and I should have but it seemed like extra drag. I didn't consider the stainless pipe to fail (see attachment)
[quote]
But if you truly come up short; fat foils stall much less easily, & are more forgiving when they do. So with that, & a ballpark idea of the size & shape of your previous rudder, you'll be able to come up with something.

It was about half the size of the main rudder so I believe a little bit overkill as my boat is only 27ft and about 4 tons. This seems like a good thing though. For example I could lock the main rudder and use the vane rudder and be able to steer the boat with it, and in light air, I could keep course downwind with the main rudder locked and vane rudder locked vertical. In rougher conditions, the main rudder moved hard over with each wave if needed.

PS: If the whole foil section thing is just too much, or complex, for whatever reason, consider this. --> There are plenty of boats out there with 0 foil section to their rudders. Ditto on many centerboards & keels.
As a square plate, actually has better lift characteristics than many of the crap foil sections out there. Or even poorly executed, great foil shapes.

Poorly executed great foil shapes? What is that?

I'm going to just use the NACA foil section off wikipedia and stretch it to the needed dimensions then trace that off my computer screen. Of course counting for the thickness of the glass to add later.

I wonder how well a longer thinner blade would work as many other wind vane models have something more like this. For this I could just stick a wooden oar in.. and maybe carve it slightly to balance. It would be interesting to try, but before leaving I will try to build something more similar to the original.

Originally Posted by Orion Jim

http://www.selfsteer.com/products/monitor/index.php

Scanmar can provide any spare part you require. Give them a call or email them. You can also download the owners manual so you will know how to maintain and operate your unit in the future. If you replace an old unit with a new unit they also offer a trade-in allowance.....and it is substantial. I know, that is what I did last year. I don't spare expense when my life can depend on it. Good luck

I checked this, and the part in question is $625. Considering I got the vane for $1000 and I don't really have a lot of money to spend much less for shipping it here, I will build my own.

Originally Posted by UNCIVILIZED

]

There are perhaps a couple of “easier” ways to build a rudder for your vane. Them being pretty much offshoots of one other theme.

You’d bond a glass sleeve onto the shaft, as detailed before. And then, to it’s centerline, along it’s trailing edge, bond a sheet of plywood, or DIY thin sheet of reinforced wood (see below). And this will act as the spine for the rudder’s blade.

You’d do it using strips of glass going from one side of the sheet of wood, around the rudder sleeve, to the other side of the sheet of wood. Repeating this several times, so that the fiberglass extends a little bit further aft on the wood each time.
And once it’s solidly bonded to the shaft, so that the glass is sufficiently thick to resist the torsional forces within the rudder. Then seal the rest of said piece of wood.

After that, epoxy some any of the following to that center spine piece; thin sheets of plywood, strips of milled to size (regular) lumber, sheets of foam (or balsa).
Progressively sealing each piece as you go, & using epoxy & glass in order to create as much of a monocoque structure as you can.

Then plane or sand this built up blade into a foil section. Seal it up with a few layers of glass & epoxy. And template & fair it to shape.

There would perhaps be a bit more sanding, but you wouldn’t have to deal with filling a blade in between foil sections bonded to the shaft.

It would surely make a good rudder, but it also sounds like it's going to cost a lot more for all the epoxy and glass to build it and also wouldn't make the ideal foil shape as easily. There is nothing I hate more than sanding fibre glass (besides sanding bottom paint)

I wasn't going to fill between foil sections at all.. just leave air there. I can put fishing line tight across the sections so the glass won't sag before the epoxy sets.

--> As to the DIY sheet of thin, reinforced wood, referenced above. You’d need to have a flat, smooth worktop, with some kind of “mold release”. Be it a well waxed sheet of Formica or Melamine, some Visquine sheet plastic (or a trash bag), or even some overlapping strips of packing or duct tape.

Then you’d take a thick piece of solid lumber, & slice off a bunch of thin strips. Perhaps 1/4” (6mm) – 3/8” (10mm) thick. And glue their edges together on the worktop, with each piece placed such that the opposite side as compared to the one nest to it, is facing upwards. So that there's a natural balancing out of the wood grain's bias.

Meaning that you're doing it to minimize the natural tendency for your flat piece to want to warp, or cup, in one direction.

And after that, simply sand/plane both sides of the wood to form a smooth, flat surface. And add a couple of layers of glass & epoxy to each side.


PS: BTW, in the long run, a stainless pipe section would be preferable to mild steel (and Titanium would be one notch better yet, given the right alloy), but again, that's in the long run.
Although, obviously, you want to coat as much of the pipe as possible. With paint, or any other corrosion preventative.

Well in the long run stainless steel is not good if constantly underwater.

Also, the rudder shaft's weak point will be the seal at the top of th fiberglass. So some folks will bond the top 1/2" or so of the fiberglass to the shaft using a flexible adhesive, like 5200. With the lower section of the same piece of glass being bonded to the shaft with epoxy.

so this prevents metal fatigue, or prevents separation of the glass to the shaft with flexing?

[Snowpetrel]

What about something like the old Hasler gears used.

http://www.jesterinfo.org/HaslerSPVaneGear.pdf

They had a wooden blade that fitted into a set of checks welded or bolted to the shaft. The wooden blade pivoted up and had a shear pin to hold it down. It would be pretty simple to bolt on a couple of temporary plates of steel or aluminum or even hardwood if stainless isn't available and then weld on some permanent stainless steel ones latter.

Get a nice bit of 4"x1" hardwood planed into a good approximation of a naca 0020 or 0025 or so with a 20% balance should do the trick.

Balance can be fine tuned by raking the blade slightly fore and aft if needed.

Id just paint it with epoxy and antifoul it. No metal underwater. If it warps slightly plane it back into shape, or build a new laminated one latter.

[Snowpetrel]

Belchers wooden servo rudder used a tapering section. 125 long and 35mm wide at the top and 17.5 thick at the bottom with a 22% balance. Naca 0028 to a Naca 0014 at the bottom. He carefully weights it to be neutral in the water and balanced around the pivot when floating.

[bobnlesley]

The comments about the tube being sacrificial and the hole at the bootom of the blade for a safety line are true, but 'after the horse has bolted'.

Sadly I'm not at the boat to measure - back in another two weeks if you're still stuck then - but a read through the Monitor Manual (available online as a pdf) show the pendulum blade's length to be 24"/610mm. Knowing that and picturing my own in my mind, I would estimate that it's about 6"/150mm fore and aft and perhaps 2.5"/60mm thick at it's widest point, that and the tube-socket both being about 1.5"/38mm from the leading edge. I would suspect that provided you build it strong enough (it's got to be taking some serious loads) then the precise dimensions probably aren't that critical? I recall spending days checking/re-checking/shimming/adjusting ours to set it up perfectly when we first installed it and subsequently came to realise that with the myriad of possible positional combinations due to boat movement, waves, heel angle, etc. it really has to be capable of working over a wide range movement of the boat so the odd millimetre or degree here and there can't possibly matter; particularly on a relatively small boat like yours or ours. Good luck.

[stevebein]

IT seems like a lot of people went to a lot of trouble and effort in recommendations. With all the planning etc, unless you are totally away from any mail or shipping, it would be cheaper and easier just to buy the replacement and make sure the safety line is secure.

[Sailormantx]

23.25 inches top to bottom, 8 inches from to back. Blow up the attached picture to full size and use it to copy the foil shape. I am using .065 thickness safety tube, it is 1.5 inches diameter. This is a bit stronger than Scanmar recommends, but it will still break without damaging the vane. I broke 4 of them on the last crossing due to being fouled by a massive area of sargasso weed, so this is proven to be a workable size.

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