The Offshore Voyaging Reference Site

Planning a Refit—Rudders, Repair or Replacement

In Part 1, I built on Colin’s article to understand just how bad the situation with rudders on old fibreglass boats is. If you have not read that, please do so now, otherwise what follows will not make sense to you.

Now let’s get positive and look at what to do if we find that our boat, or one we are thinking of buying, has a defective rudder, as well as what the fix will cost us.

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Alex Borodin

I have no recommendations to offer, unfortunately – my rudder repair/replacement is still on the to-do list. But I do have a question to resident engineers: why doesn’t anyone talk about replacing internal rudder structure (or chainplates, for that matter) with super duplex steel, instead of 316? I’ve heard that super duplex grades are much more resistant to corrosion in marine environment, but the lack of the discussion of them makes me worried that I’m missing something.

Alex Borodin

Hi John,
Well, as you correctly suggest in the article, a carbon rudder is way overkill for my old boat and would be a waste of money. I wonder about SD steels, because the cost is nearly the same as 316, which is not true of carbon or titanium. And they have the promise of reduced worries about crevice corrosion and stress corrosion cracking. I recently received exactly the same quote for chainplates made of electropolished 316L or super duplex steel.

The rudder on my boat has bronze stock and plates. I have to consider alternatives, as bronze is quite pricey here in Europe.

I have yet to drill into the rudder and so don’t know its condition yet. Maybe I’ve won a lottery and won’t need to replace the rudder. Who knows? But it pays to consider my options beforehand.

Richard Elder

Hi John
My thought about carbon rudder stocks for cruising boats—- If the designer/engineer has designed enough of them to fully understand what he is doing he will have been designing for race boats and will be firmly embedded in the weight saving mentality. He needs to double or triple his scantling calculations in order to design a shaft that won’t break under any conditions!

Richard Elder

Hi John
A few weeks ago in reply to Colin’s thought that building rudders out of wood would be too expensive I outlined how I would approach building from wood in a production situation. As I learn from your article how best-in-class companies like Foss (Florida) build their fiberglass rudders I’m starting to believe that my CNC wood manufacturing procedure may even be superior:
This manufacturing process is proven in millions of stress tests and is standard practice in the construction of alpine skis.

1- Western Red Cedar @ 23.7 # per CU’ imposes no weight penalty vs 20# density foam. The overall product may indeed be lighter because the exterior fiberglass shell doesn’t have to be thick enough to withstand foam expansion pressures.
2- CNC milling of the two Cedar rudder halves allows me to create two precision O-ring grooves in the rudder shells. During assembly two O-rings will be slid over the shaft and compressed. Far superior to leaving a gap and hopefully filling it with 3M 5200. (Which has a good but ultimately limited underwater life span)
3- Foss needs to have hundreds of rigid molds in order to build all of the rudders they have produced over the years. If they are stored according to standard boat yard practice, they will have become less than fair in the sun and weather. I can store the precision digitized dimensions for every rudder in the world on one disk or memory stick. A single CNC milling machine can build hundreds of different designs, every one more precise than any molded fiberglass rudder. .
4- Western Red Cedar is extremely rot resistant, although not impervious like high density foam. However the rough blanks are epoxy laminated from 3/4″ stock, creating a water barrier at each seam should any water enter the rudder.
5- One of the faults of standard fiberglass rudder construction is that the internal metal bits are asked to transfer the rotational loads to low density foam or imprecise contact with the exterior skins. In my procedure the rotational loads are all carried to the wood by high density epoxy/silica filler in the remaining small gaps between the bulkheads or paddles and the CNC milled recesses in the wood.
6- In my procedure I do not have to rely upon blind pouring and expansion of foam for QC. Each half is precision indexed to the opposite, and final assembly is accomplished with a hydraulic press just like HEAD used when they built my downhill race skis.


Scott Arenz

Hi Richard,

I really like the concept you’ve outlined for using CNC machining to build a wood composite rudder. The compressed seals at the shaft entry, the positive structural connection of the internal armature to the shell, plus friendlier materials to work with for at least part of the process are all advantages, to my mind. The equipment needed is also highly flexible for other types of woodworking.

A further advantage might be greater ease of engineering and fabricating a breakaway section for the lower portion of a spade rudder. Having bombproof continuous structure all the way to the end of a vulnerable cantilever doesn’t make a lot of sense to me, but unless I’m mistaken, seems to be the status quo for rudders. To my amateur engineering brain a breakaway section would be a relatively easy opportunity to help prevent a potentially catastrophic cascading failure mode. (Grounding = bent shaft / broken tube & flooding, loss of steering when off a lee shore, etc.)

All in all, perhaps there’s potential for a side business for someone who enjoys this type of fabrication and could successfully demonstrate & market the various benefits.

Richard Elder

Hi John
Actually the set-up cost for my proposal would be far less than a company like Foss experiences. For every new rudder shape they have to build an expensive mold and then toss it out in the back yard until somebody comes along needing the same design. With CNC the manufacturer only needs to input the codes and can produce hundreds of different models from the same machine. I did ERP consultation for a small furniture manufacturer, and can testify that the CNC machine they employed was not particularly expensive.

On the other hand I am the last person in the world who would try to build a business that required convincing yachty customers that wood is a good engineering material—-.

Eric Klem

Hi Scott,
I like the idea of a breakaway section in theory but they can be a bit tricky in practice.  The trouble is making something that doesn’t break away during hard but normal use but does break away before everything else is damaged.  The issues are due to a few things:
– Fatigue: As an example, in steels and stainless steels, there is a fatigue limit where if you keep the stresses below that limit, you will never have fatigue issues.  This is great but the limit is 1/3-1/2 of the normal yield stress depending on alloy so you need to oversize to account for this.  Since the most likely material we are talking about here is fiberglass, it suffers from fatigue as well and has the added complication that it is much harder to predict analytically because it is very dependent on fiber orientation and type so rules of thumb like with steel are too simplistic.  I don’t know enough to comment on fatigue in wood.
– Manufacturing variability: The way that fiberglass rudders are actually built is not super repeatable in terms of strength, it isn’t awful but it isn’t like machining billet steel.  To really control this, you would need to have tight environmental controls, very tight resin ratio (prepreg?), precision cut and laid cloth, etc.  If doing normal hand layups, because of the variability you need to add a decent safety factor to account for this variability.  Of course, if we go to Richard’s idea, we can machine very precisely but wood is not very homogeneous so you have the same problems as fiberglass.  Also, wood changes properties over time more than the other materials.
– Safety factor/poorly known loads: Above I suggested that you needed to account for fatigue but not including a safety factor to go along with this is pretty poor practice.  When loads are really well known and you have a  very consistent and predictable manufacturing process you can run quite low safety factors on top of allowances for things like fatigue but in this case, neither is true.  As discussed above, manufacturing is not all that consistent.  Maybe more importantly, loads are actually not that well known.  Are you designing for a wild broach in 30′ waves?  Has anyone ever instrumented a rudder in those conditions?  Can you extrapolate data from one design and weather system to another?  This doesn’t mean you can’t design for it, you just need to include a bigger safety factor to your expected loads.

When you combine all this stuff, it is easy to convince yourself that the breakaway section suddenly needs to have a static strength that is nominally 10X more than your max predicted load.  Then to make sure that the right thing breaks, everything else must be much stronger than this.  It absolutely can be done but the engineer doing it needs to do a proper tolerance analysis on the whole thing and I am not talking just dimensional tolerances, I am talking loads, layup strength, etc.  It would be very easy to design only to nominal and find that the breakaway either fails to early or isn’t the thing that fails despite the analysis saying that it should work.  To make a breakaway practical, you generally need to have the breakaway load be much higher than all other normal loads.


Eric Klem

Hi Alex,

I don’t have a great engineering answer for you on why one of the duplex grades is not used, maybe someone else does.  Thinking about the required properties, I can’t think of why it wouldn’t work well.  As you say, duplex does better than 316 in terms of corrosion and strength and machining and welding it are not significantly different.  It has been a few years since I have spec’ed any duplex but in my experience, 2205 was more expensive than 316 so it is interesting to hear that you got similar quotes.  One other thing to watch is ductility where duplex is usually not as good as many other grades.  If I remember right, you can’t cold head it for example.  Also, if the elongation at break is low, that is a decent proxy for low toughness which can also be measured in a standardized way (this is Foss’ concern with carbon fiber).

Looking at why this sort of thing happens is always interesting.  To be perfectly honest, many mechanical engineers get a list of materials they are comfortable with and then stick to it, we can’t be experts in all materials, even materials engineers have certain areas they specialize in.  For example, I design robots and our entire materials database has less than 30 materials in it for several hundred custom parts in each generation of machine and that includes all metals, plastics, etc.  I added a new grade of PEEK the other day for a very specific application and it was met with some degree of resistance since we would need a new supplier, etc.  There are a few reasons that we get away with a relatively short material list, the most important probably being that we often design for stiffness not strength and the variations in modulus of elasticity between different grades of the same family of materials such as stainless are low, you have to switch to aluminum or another family of materials to make a big difference.  I am guessing that naval architects have even fewer materials that they reach for than engineers and when they get into really high end race boats, then you get a bunch of engineers involved.  It may also be that many of them simply don’t understand the issues with stainless in some environments, learning the issues can actually be quite tricky.  Also, duplex is only ~30 years old, it takes a while for a material like that to come into widespread usage, the first time I ran into was a very specialty casting application and it was a new material to both us and the casting vendor.  Finally, most people designing stuff automatically put some cost consciousness into their design and then you can also have cost requirements coming from outside whether reasonable or not.  None of this makes it right or wrong but it does explain why some perfectly good and maybe better materials are sometimes not used.

And then the question is also what other materials should we be looking at.  Bronze like you have can be attractive although it has lower strength and can cost a lot.  Titanium is always interesting to contemplate.  At least 1 manufacturer tried fiberglass and discovered their implementation needed improvement.  It may well be that there is not even 1 best material as it becomes design dependent with stress, deflection and other factors dictating the material requirements.


Alex Borodin

Thank you, Eric! That’s all great food for thought.

Nick Burnett

I had the rudder on my ’74 Tartan 26 cease steering off near Monhegan in 1990. I was luckily able to bring the boat into Port Clyde by adjusting the sails to steer. There I found that Tartan no longer had plans for the boat. The first attempt to get to a haulout harbor resulted in having the rudder actually fall off (another story). To get the boat hauled miles up the coast in Rockland I had to fabricate a steering sweep out of a dock plank and lash it to the stern pulpit. I felt like a Viking, and it worked! I had the boat hauled and lowered the stock. I used my memory and the skeg to design a shape as close as possible to the original one. I had a a stock made up and had as tangs welded on. I then built a new rudder by laminating many layers of marine plywood around the stock and frame, fairing it with a grinder and sander. I poured thickened epoxy through the small inconsistencies in the layup around the stock. I sailed the boat for several years with no noticable performance issues. I eventually sold the boat to a young couple who sailed it down to the Virgin Islands and had no problems. The last I heard they had sold the boat to buy a larger one. Probably not perfect, but it worked for years. I now am very concerned with checking my rudder for cracks or signs of water ingress.

Andre Langevin

in 2013 i had a friend with a Catalina 33 having a lot of delamination and osmosis on his spade rudder. We looked at the options. I had the experience of building rudders on my boat and told him the cost by calculating the stringers required and the plate (11 Ga). Repairing a rudder on a boat with stainless steel is easy because 1) most of the time you have the rudder shaft in plain 316 2) the rudder is isolated from the electrical system of the boat. Or can easily be.

We templated the old rudder, found its original NACA profile and reproduced it. Took a day from 7h00am to 3pm at 2 guys. Stainless steel cost was 400 $. Welding furniture at 200$ A little bit of fairing was required 50 $. And a paint job. His rudder costed him about 800 CAD and was lighter than its fibercounterpart, stronger, impervious to water. I had sailed and raced since.

Interestingly, a rudder with all the mechanical constraint that it is subjected to, is a part where metallic construction have a lot of advantage and not so much weight challenge. Metallic rudder are hollow…they have positive buyoancy…

Andre Langevin

Hello John I agree its just an amateur-boatbuilding fantasy. Also you are right that SS should not be used underwater but in this specific case we knew the rudder stock was not bound to the ground. And please do not compare aluminum saildrives to stainless steel, these are not the same and agreed the number of parts of a saildrive make this a cocktail of dissimilar metal that should never exist.

3 boating friends out of 5 ( i don’t have many) owner of various size polyester boat have had to redo their rudders because of osmosis, impact or whatever in the last 10 years. Altough no boatbuilders, they tackled to do it in their garage just to save some money in the winter while there is nothing to do outside here in Canada. I HATE the smell of fiberglass resin but i have to admire these guys that agreed to spend several days chipping the rotten wood, balsa or whatever inside then replacing it with fitted new stock. Its is a 2 week job to redo a rotten polyester rudder.

We even had our local racing team with their Open 60 (Yes there are 2 Open 60 at our marina !!!!) had to redo the rudder because they hit a fish on their last St-Malo-Quebec race. Seems it is a regular maintenance chore on these boats. They did it in front of everyone at the marina… so this is not rocket science.

Lets correct my first saying that a replacement rudder could be made in normal steel (not stainless steel) plate welded to the SS rudder stock. NACA profile are public information and the transverse that give the NACA profile to the rudder can be laser cut for very cheap. Steel is about .50 $ per pound and once laser cut the cost is about .75$ per pound including the nesting process. Laser shop have huge leverage because they buy so much steel. I can guarantee you that any decent metal worker can do a single rudder in less than a day. Another day for preparing of the laser cutting. ( i carry the coordinates of my rudders in a .dwg file just i case i need to have them rebuilt)

Once protected by epoxy + barrier coat, there is no reason a rudder with two small anode cant do many decades of service.

Andre Langevin

Love your sense of humor John, at least the readers now have an idea of what can be made in the span of available solutions, this one having some value in a survival situation (steel can be welded with 2 *12v battery) so if in their pursuit of adventure they broke their rudder on a remote island with not so much spatial material around, they could have it repaired.

To my opinion to put a stainless steel stick in a fiberglass kind of lolipop and dip in the water may also be running after trouble. The top join between the inflexible stainless steel rudder stock and the polyester is a sure place where water can enter, especially with temperature variation and gravity wanting everyting to go down.

Also, a good sea story: maybe to have all metal rudder would have saved the rudder of a friend on is Legend 45, caught in a squall between Gaspesie and Magdalen Islands with 8 sailing students onboard, they were battling the sudden 50 knots winds when they hear a “crack” and the boat lost steering. In the turmoil of the situation, the owner put his head under the lazarette searching for the cables and cardan, everything was there. But the boat non navigable. When the wind calmed down he put his head under water and the rudder has disappeared! They managed to came back to Magdalen island by hooking up the largest sail bag they had at their stern over a Y rope arrangement. When the boat was docked, he manage to remove the rudder stock; a massive 4 inch 316 shaft, just below the waterline it looked like a sharpened pencil…perfectly machined by some powerful lathe. That guy had friends at the Hydro Quebec research center and arranged to have the remaining of the rudder stock sent there. It appears upon analysis by the researchers at the center that only a “superbolt” of more than 100 Gigajoule could have vaporised a 4 inch stainless steel cylinder.

a true story, the guy still sail on his boat. Now he is not sure that it would be better to be hit on the mast than on the rudder…

Marc Dacey

Just as a non-contentious data point, the guy I sold my ’73 Viking 33 sloop to in 2016 opted to have the original rudder, which we both knew was at its “end of life”, with a stainless steel replacement. The boat is in fresh water, and the owner is on a mooring well away from any potential electrical issues and so deems it an appropriate rebuild material. Time will no doubt tell if it is a mistake or not, but a year later, it steers the boat as well as the old one it replaces did, but without cracks and weeping.

Frans Botman

Reading the above, can anyone explain to me why there would be a problem with stray current on a stainless steal rudder but not on a Foss rudder with having a stainless steel shaft?
I mean, in both cases there is SS involved in direct contact with seawater.

Bruce Bayne

I’m in the middle of an engine refit (Beta 43) in my 1980 Fast Passage 39, and after reading the previous article on rudders decided to have a good look at mine. It was leaking rusty water, so decided it would be prudent to add a new rudder to the refit, since I was already on the hard.

I did some research on rudder manufacturers and found the two Foss plants (FL and CA), and received quotes from each. Jefa replied stating that they only made spade rudders. Mine is not a spade, so they were out of the running. My boat yard (The Boat Yard at Rocky Pointe Marina near Portland, OR) said they had heard of a rudder company in Idaho, so I reached out to and had a great conversation with Jeff Alexander. Total cost including shipping both ways was $3879.39 for a custom made rudder.

It came with one coat of Interlux 2000E barrier coat, so the yard put 4 more coats on and 2 coats of bottom paint. We’re lifting the boat tomorrow and installing it for a launch the following day.

Edward White

I recently spoke to ruddercraft and they don’t have original molds for many production boats.
While he sounded competent etc, the Foss Foam product was much less $$. The California plant and Florida plant split 25 years ago. Most production boat rudders ( I have 1983 Cal 35-2), especially ones from the left coast are made in Cal….

Petter Mather Simonsen

For those inclined to rebuild their rudder DIY Mads @saillife on youtube did the complete job for an old Warrier 38, including new molds. It was quite a bit of trial and error. You will find some good documentation starting from here: After watching his work, you will either be solidly prepped for your own process, or maybe reconsider the merits of DIY.

The designer Dick Koopmans Sr. has a different approach to rudders on his aluminium centerboard yacht; both rudder and huge stock in alu, welded shut so no mix of different materials with all that entails. Rudder stock fully supported from below. Far from a racing design, but rock solid – literally.

Picture here

Petter Mather Simonsen

In the picture of the rudder, the notch at the top aft end of the rudder is made to fit and lock in place a piece of anchor chain. The use is for swinging the rudder sideways (steering) with ropes from the cockpit in the event of a steering gear failure. The bit of chain with two lengths of rope attached is thrown overboard and then pulled in place in case of need.

Eric Klem

Hi John,

Thanks for the information on the cost of this, not money I would love to spend but definitely not unreasonable for what you are getting.  I am at least glad that Foss exists and we have a decent option beyond DIY and going to the local yard who certainly won’t be specialists.


Lee Corwin

I’m curious. What would be the difficulties of a transom hung rudder with a sugar scoop aft of the transom. The rudder could be balanced. The sugar scoop serving as an end plate decreasing risk of cavitation. Yes a forward strike could cause it to indent the sugar scoop preventing it from being able to steer. But the canoe body should remain intact with proper construction.
Currently have an Outbound 46 with a balanced spade. After seeing many boats where the rudder is keeping the skeg on not the other way around think whatever design you sail what’s most important is engineering, execution and maintenance.

Bill Attwood

Hi John
Just info, which you may already know. The Rustler 36 has a transom hung rudder. I bought mine with wheel steering (quadrant mounted in lazarette) but have converted to tiller; a very simple job. My Windpilot is mounted on a bracket with 4 arms, 2 each side of the rudder post and bolted through the transom. It worked/works well with both systems.
Yours aye

William Koppe

Hi Alex,
Duplex stainless steel is roughly 2.5 x as strong as 316 and that makes it suitable for rudder stocks. It also has far better corrosion resistance as well as far better fatigue resistance.
Welding needs to be done with pulsed MIG so as not to put in too much heat which if cooled too quickly can lead to a phase change . This is when the mixture of 316 and hi tensile steel unravels to one or the other forms. This is rarely a problem but should be considered.
In using 25 kilometres of duplex welding wire we used a ferritescope to test for phase change and found none.
Next all metal rudders should be filled with oil. This is because no welds are indeed totally watertight but have tiny pin holes. We saw this in xrays and Lloyds welding rules specifically allow a % void .
A duplex rudder should be isolated as it is more active than most other metals.
While the potential is there for hydrogen embrittlement , which occurs in water temperatures over 26deg C it should not be a concern if replacing a 316 rudder stock with duplex of the same size.
No zinc anodes should be fixed to the rudder.

Alex Borodin

Hi William,
thanks for your input.

William Koppe

Hi John,
I am surprised that you don`t like the idea of a full 316 rudder but are happy to have a 316 stock. The main issue with 316 below the waterline is crevice corrossion which is where the 316 is denied oxygen. The worst affected area is just inside the rudder bearing tube.
So given that we already have those issues with the fibreglass rudders, why wouldn`t we take advantage of the benefits of a metal rudder which can be made up by any stainless fabricating shop for far less money.
It is simple to make as you also weld the horizontal tangs ,laser cut by the stainless supplier to the NACA shapes, to the stock.
The covering skin is then stitch welded to the frames and the stock ,and the opposite skin is stitch welded in laser cut slots. The edge is then welded closed.
I would certainly do this rather than buy an expensive Foss rudder.
Finally if I were building a Foss type rudder I would prime the stainless with International 820 primer as a lot of paints epoxies etc do not adhere to stainless very well.
The finished rudder after fairing need a quality paint regime which should include a glass flake paint. Two coats of primer a barrier coat the antifoul does not cut it.

Frank Roberto

Hi John,
After lurking for nearly a year (and enjoying the new and archived content of AAC anonymously) you’ve hit on a topic that I’m currently dealing with, namely the impending replacement of the skeg-hung rudder on our 1997 Caliber 40 LRC in the Pacific Northwest. I have read on several Caliber owners’ forums of wet rudders found during surveys (more validation of the importance of a good pre-purchase survey) or during routine haulouts. Our rudder was found to be wet both by tapping and by moisture meter last May, and we received a concession on price to have it investigated. When we finally hauled out this month to do further examination of the moisture, the rudder was observed to be delaminating and weeping water from a 10″ crack on the port surface. We apparently hauled out not a moment too soon!
The original Caliber rudders were built by Foss Foam in Florida, and as you suggested, the molds are still available. We’ve decided to completely replace the rudder stock and web, rather than try to re-use those components, both because we would always be suspicious of the metal and weld integrity, and our plan to embark on offshore cruising in the next 5 years. We’re expecting the total cost of the rudder with shipping to be somewhere around $5000.
One thing that didn’t come up in your recounting of your discussions with Foss was that painting the rudder a dark color is not advised, as it may contribute to expansion and contraction from exposure to sun and accelerate deterioration. Written instructions recommending light bottom paint colors for the rudder were found in the original boat documentation but of course ours was painted a very nice Interlux blue. I’ve seen recent photos of some of the Caliber rudder replacements with white rudders in response to that guidance. After incurring the cost of a new rudder, no one is taking any chances!
Another option besides Foss I discovered while exploring alternative sources was Competition Composites Inc. (CCI; formerly Phil’s Foils) in Ontario, Canada. They can take 3D scans of your existing rudder and use CNC machining to produce two halves of solid foam core to sandwich the rudder post, and skin the rudder core in fiberglass. The least expensive option is to use your existing rudder stock and web, but you could also have them build a carbon fiber post (for considerably greater cost, of course.) Here’s a link to their general process: The estimate to build a new rudder for my boat re-using the old rudder post and web was considerably less expensive than the Foss estimate, but did not include the additional cost for shipping of the old rudder on a custom oversize pallet to Canada and return shipment of the new rudder.
Sorry about the length of my comments, but I thought I could add more detail to your 2-part article with my in-progress rudder replacement and another potential avenue for members to consider.

Marc Dacey

A fine example of a member post full of useful info. I had never considered the light paint on an exposed rudder option, either. I knew about Phil’s/CC because I hang out with racers here in Ontario, and they are well-regarded. I did not, however, know about “Florida Foss” and “Not Florida Foss”. This place goes deep…

Richard Elder

Hi Frank
Interesting that you would consider choosing another Foss rudder when you have a failed model in front of you!

The CCI process is similar to what I have been suggesting for cedar. However my earlier comment about race boat engineering still holds true as the samples on the CCI web site all are designed with the light-is-right mentality. CoreCell is certainly an excellent foam, but it is usually found in 4# and 6# density. Your boat is no race boat. Get CCI to machine yours from 20# foam, make sure they only use epoxy resin, and include the O-ring seals as I suggested and you’ll be golden.

Petter Mather Simonsen

Informative video from sailor Patrick Childress when he opens up the rudder of his 40 year old Valiant 40; drop, cut open, inspect, fix, close, reinstall.

Richard Elder

AKA how not to repair your rusty old Valiant rudder. Interesting that Childress found the foam “rubbery” which means it has little structural strength, but proceeded with a small localized patch. The same author has another video in which he cuts a square section out of his foredeck under his windlass where the core is rotted out and then shows us how not to properly repair high stress areas of the deck.

re Foss/Caliber rudders: I don’t consider a 23 year service life from new to potential catastrophic failure an acceptable product life expectancy for such a mission critical item.

Gari Williams

I think that it is a slippery slope to be criticising individuals based upon watching a video of them. We all have different standards. It must also be taken into consideration the budget involved and the location in which work is being done. I wish PC all the best in his ventures to circumnavigate.

Richard Elder

Hi Gari Wyn
I agree in principle that the level of discourse on this site should remain at the level of technique rather than the personal— and as moderator John certainly works to uphold that standard. To his credit, John is not afraid of using himself as an example when he screwed up and learned from it.

On the other hand, Patric Childress represents himself as an expert, giving advice to wanta-be cruisers through a regular series of video presentations. As such he should be subject to technical criticism when he advocates procedures that appear to be erogenous. And as a self-promoted expert he should not have his identity hidden from future viewers.

When somebody opens up a small section of a rudder and finds rusty, improperly designed connections to the shaft surrounded by “rubbery foam” and elects to re-weld it and cover it with a patch they have not performed a seaworthy repair and should not be encouraging others to follow their expert advice. When they cut a square hole in the fore deck of a Valiant 40 of that vintage and find completely rotted balsa core it is not sufficient to reef out a bit of core under the remaining deck at the edge of the hole, shove some fiberglass under the 90 degree edge, and glass it over. If the bedding compound under the adjoining mooring cleats is of the quality I have observed on every Uniflite Valiant I have surveyed it will have long ago failed and rotted out the core under the critical cleat.

We may all have different standards, but when we venture out onto the ocean on a small boat the Ocean doesn’t care what we personally think. Rudders either steer the boat or they fail. Standing rigging either stands or it falls. And when you are praying your anchor holds during a Category 4 hurricane you better pray that the windlass will not pull out of the foredeck if that is all that is holding the boat to the anchor.

Frank Roberto

Thanks everyone for the comments and questions. John’s 2-part article resonated with me as it reflected much of my experience in considering how to replace my own rudder. I recently heard a boat show instructor paraphrase an aphorism about boats, something like “bad decisions and compromises.” Anyone know the actual saying? We’ve probably all made a lot of the latter, and hopefully only a few of the former.
Choosing Foss Foam in Florida for a new rudder for me was a compromise compared to the optimal solution of having a CNC-machined solid foam core rudder built around a new rudder post, that considered not only turnaround time, cost, the existence of the original molds at Foss, and that the original rudder had lasted 23 years. I hope to get at least another 23 years from the new one and plan to paint it a light color fwiw.
BTW, in response to John’s question about the west coast and Florida Fosses, I too have heard from yard managers and read on other forums that there is a difference. This includes availability of molds for your particular rudder.

Marc Dacey

I see you are familiar with my carpentry. Still, good advice.

Terence Thatcher

A couple of things: Is the Duplex stainless the same as this Aquamet 22? I just got a new rudder from Foss, and they used 316, which is ok but perhaps not as resistant to corrosion. On quality of their current products over past, one of the things I like is they now rout out and seal with 5200 the glass/post interface. Much better chance of resisting water intrusion. Finally, on the light color: as I understand it, Foss is concerned with foam expansion when the boat is on the hard and sun is glaring down on the rudder. They say if you want to use dark paint, just make sure you drape the exposed rudder with a white cloth. I cannot believe an exposed tip sticking out of the water would be a problem, especially if it were tucked under a transom, but you could always ask Al or Dave.

Mark Swanson

I had a rudder for my valiant 40 made by Foss Foam Florida last spring. The boat was in Green Cove Springs about 1 1/2 hrs from Foss at the time. I drove the old rudder to them on the roof of my Outback and picked up the new one a couple weeks later. Being able to see and talk to them face to face and see the operation was a plus. I was willing to have a new shaft made but they assured me after inspection that the old one was in great shape. As someone who use to make similar rudders back in the day I can say the quality is good. Great people to work with too. I put a couple thousand easy miles on it last summer. Not enough for any conclusions but so far so good.

Mark Swanson

I had given the okay to replace the plates and shaft if needed. I actually expected that they would need to. They were not rushed. I told them to take whatever time was needed but they found the shaft and plates to be in very good shape. I can’t find the record of what I paid but it was under 3k.

Devon Rutz-Coveney

Hi Mark,
Thinking about this job for our Valiant 40…. what year was your Valiant built?

Dick Stevenson

And, Mark, what were the symptoms, if any, that led to the rudder work?
Thanks, Dick Stevenson, s/v Alchemy

William Koppe

Hi Terence
Aquamet 22 is close to duplex 2205- yield strength 380 to 480 for duplex, brinel hardness 341 to 293, corrossion resistance Pren 34 to 35.
Chemical composition while similar eg Cr 22 to 23 has differences eg Mn 5 to 2 and particularly Carbon .06 to .03
This higher carbon will give issues with welds and carbide precipitation so requiring annealing after welding for the Aquamet.
Duplex 2205 welds also have to be treated by mechanical abrasion or pickling.

Paul Y

Lagoon uses Fibreglass rudder shafts in many of their cats. Seem to work well and no corrosion. They look to be solid glass, not tubes. VERY solid.

Eric Klem

Hi Paul,

Like John, my impression is that fiberglass rudderposts have a fairly poor track record with one manufacturer in particular having had several failures.  The question then is was it a design/construction error or is there a fundamental reason why it is not as good.  There are a few key differences in properties between fiberglass and stainless.

One important difference is modulus of elasticity which is a measure of how stiff the material is.  Depending on the exact layup used, the modulus of fiberglass is 3-10X lower than that of 316 stainless (3X is the realm of E-glass and most other stuff is close to the 10X end of the range).  This means that you need a larger diameter rudder post to get the appropriate stiffness affecting what the rudder profile can be.  While people love to talk about how strong stuff is, my experience is that I am limited by stiffness of parts far more often than by the strength when I design stuff.  For a rudder, if the shaft is not stiff enough you can have everything from mushy helm feel to contact of the rudder and hull to binding in the bearings to cables coming off the quadrant, it is all dependent on the design.  The only solution is to go bigger in diameter which affects the foil shape of the rudder.

Fiberglass can actually be stronger than 316 stainless but if you exclude E-glass and S-glass, you are usually looking at a laminate that is less than half the strength. Composites are ever more particular about how you specify them than metals, specifying frp alone is no guarentee of what you will get.  This again means that you need to go larger in diameter.

Stainless is quite easy to make plain bearings for, there are many grades of plastic that work well.  Fiberglass is a bit trickier of a material to put in a plain bearing application and get good life from.  Similar to bearings, shaft seals/stuffing boxes are trickier.

The really appealing thing about fiberglass is that you can make everything out of the same material which holds up really well in a marine environment.  I find this aspect really compelling and for certain applications where the shortcomings could be dealt with, I believe that it could make this the best option but you can’t simply design for stainless then substitute fiberglass.


Edward White

I’ve run into rudder issues on my 1983 Cal 35-2 and at the end of the day decided to have a new one built by Foss Foam, Newport, CA. I’m doing this for peace of mind decided by the hassle of transport and rebuilding of a rudder that is very heavy (loaded with water) and suspect at best. It’s a no brainer for me. Additionally, the new rudder will be of a slightly different design, more fluid dynamic, and a bit shorter than the original which reached down nearly as far as the keel. I’ll also be carrying a lot less weight at the stern. The cost including shipping is about $2500. A lot less than what was anticipated. To me, rebuilding a waterlogged 37 year old rudder would never allow me peace of mind. I plan on using the West System rudder bearing replacement process to eliminate the sloppiness after I hone down the tube. I was surprised to find there were no actual bearings when I dropped the rudder. It is simply the stainless steel rudder stock inside a plastic tube that’s enclosed in fiberglass. Built into the current fiberglass & thru the plastic tube are nipples for injecting grease, which I’ve done over the years. A lot of suggestions have been made concerning the total removal of the tube, but that would see, to result in a real fuster cluck. The process for West System can be found on page 62 of their catalog/manual…

Richard Elder

Hi Edward
The graphite/epoxy bearing procedure as invented by the Gougeons can make your helm feel like it has ball bearings. One minor trick– Wrap the shaft with a single layer of plumbers teflon tape– it provides a few thousands clearance to avoid binding, and will eventually go away. Unfortunately I don’t have a long term report on the one I did, but it was sure nice during the test sail.

Dick Stevenson

Hi all,
Perhaps I have missed it but am I correct in thinking:
That, in terms of rudder interior structure design, that most rudders have their splines “butt” welded to the shaft.
I would think that “A” frame construction would be far stronger. “A” frame meaning that the spline would come from the sides of the shaft meeting at the aft end of the rudder. Coming from the sides would allow for greater surface area for the welds in addition to two welds to the shaft for each splice pair. The “A” frame angle off the shaft would make for a far stiffer spline: butt welded splines would seem to me to be prone to “wag”, especially when the welds start to deteriorate: accelerating the rudder’s ultimate demise.
I would think that the increase in structural integrity would easily offset the increased cost.
Do either of the Foss companies employ this design: or, what am I missing in my cabin-fever induced speculation about this issue?
My best, Dick Stevenson, s/v Alchemy

Dick Stevenson

Hi John, Good to know. Wrapping the spline strap around the shaft makes even more sense. Dick

William Koppe

Hi John,
Graphite s used with stainless steel in seawater will cause crevice and pitting corrossion.
Also the A frame shown in the left photo should have a horizontal plate with lightening holes to avoid flexing when the stock rotates, and to give a very large area of weld to the stock.
This weld should be both top and bottom and should be done in 1 inch increments with cooling between to avoid bending the stock.

William Koppe

Hi John,
Personally, I would ream out the tube and then epoxy in a Vesconite Hi lube bearing.
Although these are normally thicker they can be machined to a thin wall.
Graphite is the most active material on the galvanic scale.
It would become an issue if the yacht was unused, ie stagnant water, and therefore no oxygen, or if the water temperature was higher than 25 – 26 C as this increases the chemical reaction .
Another important consideration is that the stainless steel surface should be highly polished so pitting is harder to start. Once pitting starts, the pits have a different potential to the rest of the shaft, and the shaft will corrode rapidly . This will be accelerated by the graphite.
The issue is whether the shaft can retain it`s thin protective film, which will help keep the reaction under control, and if not, a galvanic coupling will be established, which will be in direct proportion to the water temperature.
An excellent article on this is
Please note that this does not take water temperature into consideration.
I would not expect a problem where you normally cruise, but in the Bahamas a sudden failure of the shaft in under 3 months would not surprise.
In the same way batteries reduce performance in the cold, galvanic couplings accelerate in warmer water.

William Koppe

Hi John,
Personally, I would ream out the tube and then epoxy in a Vesconite Hi lube bearing.
Although these are normally thicker they can be machined to a thin wall.
Graphite is the most active material on the galvanic scale.
It would become an issue if the yacht was unused, ie stagnant water, and therefore no oxygen, or if the water temperature was higher than 25 – 26 C as this increases the galvanic reaction .
Another important consideration is that the stainless steel surface should be highly polished so pitting is harder to start. Once pitting starts, the pits have a different potential to the rest of the shaft, and the shaft will corrode rapidly . This will be accelerated by the graphite.
The issue is whether the shaft can retain it`s thin protective film, which will help keep the reaction under control, and if not, a galvanic coupling will be established, which will be in direct proportion to the water temperature.
An excellent article on this is
Please note that this does not take water temperature into consideration.
I would not expect a problem where you normally cruise, but in the Bahamas a sudden failure of the shaft in under 3 months would not surprise.
In the same way batteries reduce performance in the cold, galvanic couplings accelerate in warmer water.

William Koppe

Hi John,
An easy way to ream a bearing is to use a hole saw on ply and then glue these together to make around 100mm thick.
The diameter should be about 15-20mm less than the shaft.
Then bolt together using a threaded rod say 10mm.
Now glue a non clogging sandpaper to the outside of the circular ply.
Use a cordless drill on the threaded rod, and run up the bearing.
The cordless will stall without damage if you get out of alignment.
Apologies for the double comment.

Klaus Matzka

It seams that not only Lagoon but also Beneteau (both part of the Beneteau Group of companies) are using fiberglass rudder stocks. My Beneteau Oceanis 48 (model year 2012) is using one for the single spade rudder.

See photo here:

To me it seems that fiberglass rudder stocks – as long as the engineering is done correctly, what I would expect from the largest boatbuilding company on earth – is a great solution without many of the problems of SS rudder stocks.

I have no idea, though, what aging does to those FRP rudder stocks over the decades. Does anybody in this forum know what to watch out for with those constructions?

Rob Gill

Hi Klaus,
We have the older 2003 Beneteau 473, that has the same rudder construction. There are thousands of our yachts on the water (including Lagoon cats as you say, but also larger and smaller models than ours using the same construction), and many are clocking up big sea miles, with very happy owners. Here’s my take on the rudder system that we have taken offshore.
Construction – a stainless collar attached to the lower shaft, bearing inside a copper bush moulded into the hull directly below the well built rudder tube.
I knew of Beneteau(s) having issues with the lower bearing failing, as these were set by the factory using adhesive sealant, which breaks down with use. But I know of none where the shaft itself has failed, not even from collision or grounding, though I am sure some must have. So I surmise that our “FRP” spade rudder and shaft are “strong enough”, but also understand they are composite construction (with E-glass or alike), but can’t be certain.
To go offshore we had to have our 14.3m boat lifted and Cat 1 inspected, which showed more play than desirable in our lower rudder bearing. To get the rudder out we had to have the whole boat raised higher on the dock cradle, but cleaning out and re-setting the bush with epoxy glue was a long lasting and relatively simple fix. From then on, dropping the rudder to inspect and clean the tube and bearings is a one hour job for 2 people max, and the boat doesn’t need to be raised again, as the inspection and clean can be done in a normal cradle position. We will do this before every offshore voyage, or every five years or so.
If the worst happens and you strike an angry vengeful whale or floating container mid-Atlantic, at least your F( or C )RP rudder will break off cleanly. You can then steer with your jury rudder system to the nearest major safe port, and order a new rudder from stock at Beneteau Europe or the USA. This can be air-freighted to you wherever you are.
Many yacht abandonments seem to be caused by a damaged rudder staying in place and wave action on the bent rudder breaking up the hull causing flooding, or the vessel becoming uncontrollable due to a rudder locked hard-over to one-side. We are unlikely to experience this as the shaft will be sacrificial to the reinforced rudder tube, and massive hull lay-up (on the 473 any way).
Br. Rob

Klaus Matzka

Hi John,

Thank you for your answer. I have been reading the refit and rudder articles, that’s why I started thinking about how to survey a FRP rudder stock for fitness.

For sure FRP is not a replacement for a SS rudder stock, I might have been misleading in my post. I guess the fiberglass rudder stock would need to have a much bigger diameter to deliver the needed strength. On my Beneteau 48 it has a diameter of 140 mm / 5.5 inches at the rudder end where it enters the hull, with a light displacement of the boat of about 11,800kg / 26,000lbs.

What I ask myself is, if one has a fiberglass rudder stock on the boat, is it easier to survey, more safe to assume that it is (still) ok?

And if you plan to buy a used boat with a fiberglass rudder stock, would it be easier to be certain that it is not compromised, versus a SS one?

As for „tight budget“ mass produced boats: The Cheeki Rafiki story is why I did not wanted to make compromises after I had a grounding a few years earlier, some superficial repair by a European yard afterwards and then small hairline cracks coming back near the keel plates after fighting a storm with short and steep waves a year after the first repair. All before planning to leave for an Atlantic crossing. A Cheeki Rafiki incident must not happen to me and my (mostly family) crew, for sure!

That is why I mandated a supersonic surveyor before leaving for the Atlantic to check whether the bonding of the inner structure glued into the hull of the boat is ok. When this survey suggested some areas might not be bonded as they should/could be, I invested $20.000,- to cut open all the inner structure and do a re-lamination of the inner structure to the hull to strengthen the boat and keel-to-hull connection. On a four year old boat this might be a bit over the top for some.

See some photos here:

My thinking has been and still is, safety comes first.

I believe with such a professional repair a Cheeki Rafiki incident should be avoidable. Hope knowledgeable people here on ACC do not disagree. At least I do not see any signs of fatigue off the hull-keel joint or around the keel bolts after more than 14,000 nautical miles finishing the Atlantic circle back to Europe last spring.

On the money spent for the repair: This Beneteau production boat had a price tag of less than 35% of a same sized Hallberg-Rassy. So why not invest serious money and effort in a thorough repair after a grounding? The repair costs has been just 3% of the price difference between this boat and a HR.

I know there is the question ready to be asked „why not buy a HR or trusted offshore brand in the first place?“. Could be for a lot of different reasons…

I hope my repair story is helpful for AAC readers.

Klaus Matzka

Beneteau Oceanis 48 light displacement is 12,600 kg / 27,800 lbs.

Andrew Craig-Bennett

I have found these articles very sobering.

I’m not in North America but in the UK, with a Camper and Nicholson boat. I have had the Whitlock Mamba steering gear rebuilt but that was the easy bit. Now I need to start on getting a replacement rudder. Is there any UK equivalent to Foss?

Andrew Craig-Bennett

Thank you, John. Rather too many people in this country (including the highly proficient expert, with many miles at sea, who rebuilt the gear) seem to think that if you can’t actually waggle the blade on the stock, it’s OK!

I will ask around owners of sisters and perhaps we can get a bulk order going, to spread some of the costs.

Ignat Fialkovskiy

sorry guys, but that does look as Foss promotion.

Peter Carrie

Thanks All for this thread and commentary! It helped to convince me to have my rudder replaced. In my pre-purchase survey of an almost 50-year old Gulstar 50, thumping on the rudder made the same sound as a ripe watermelon! Fully saturated. So I bit the bullet and had the old rudder shipped to Foss Foam FL for disassembly and replacement. The internal web on the old rudder was a failure waiting to happen…


old rudder interior webbing.jpeg
Peter Carrie

…The replacement leaves much more room for optimism!

new rudder web in mold.jpeg
Ashley Wesch

Hi John – I would like to add another option to your rudder materials discussion.

As I see it, every conventional fiberglass-foam rudder is gradually corroding internally due to inevitable water entry where the stock enters the blade and oxygen starvation of the internal “stainless” steel. In just that manner the rudder on my 1985 Pearson 36 sailboat was leaking rusty water.

I decided to go the route of a new rudder with better corrosion mitigation. I went the unconventional route of commissioning a rudder from Ruddercraft in the USA. I did not have to send my old rudder, just provide a precise diagram and dimensions. 

Their unique method is to create the rudder blade from two slabs of High-density Polyethylene (HDPE). Each slab is machined on the outside to form half of the foil profile, and machined on the inside surface to accommodate the rudder stock and framework – with additional top-to-bottom drainage channels. Rather than fighting the losing battle to keep water out, this design allows oxygenated water to pass over the 316 stainless steel, thus limiting corrosion. 

The two sides are then bolted together over and through the internal framework. The HDPE edges are heat welded and recessed bolts are covered likewise. After sanding to create a fuzzy surface, a chlorinated rubber-based tie-coat primer bonded very well (Sea Hawk 1277).