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Production rudders and posts are often are an after thought to the rest of the boat. The precise engineering, construction techniques, and appropriate materials required are often overlooked in spite of the fact that a failed rudder can leave a boat unable to maneuver or worse, sinking.

As production rudders age there can be a host of issues, mostly related to water ingress into the core which causes the rudder to fall apart from the inside out. Core materials and adhesives that were considered state of the art when the rudder was built degenerate and posts become loose or detached from the failing blades. The posts themselves often corrode and fail. Even stainless steel posts fail regularly.

The worst corrosion and wear is often at the point where the post exits the hull; the worst place for it as this is the most highly loaded point on the post!

In northern climates these problems are even worse. Any water inside the rudder expands and contracts as it freezes and thaws and destroys the rudder from the inside out.

As this generation of rudders has aged we have seen more and more of them at our shop and have made repairing and upgrading them one of our specialties.


The first step is to examine the rudder for visible issues. Water seeping or dripping (even flowing!) from the interior is a sure sign of impending failure.

Visible corrosion and wear at any point on the post is also noted.

If there is water in the rudder blade we will reverse engineer another and remove the blade from the post.

Next we do a thorough inspection of the post to determine if it is worth keeping. Again, corrosion, cracks, and any signs of fatigue are noted.

If the post is good we clean it up and make is as close to perfect as possible, even if renewing welds and straightening the post is necessary.

If we determine that the post isn’t usable we measure and model it in 3D and begin engineering a new one.

In either case at this point the door is open to make any modifications and upgrades that may be desired; We can develop a new section, profile, chord, depth, or any other change.

Any new posts are made to accommodate existing quadrants, bearings, autopilot tiller attachements, and emergency tillers.


We have built well over 800 rudders and posts at CSI and our technique is very well refined and proven. We’ve built rudders for every type of boat imaginable, from America’s Cup boats to grand prix in-shore racers, multihulls, Volvo Ocean Race Boats, one-designs and a variety of cruising sailboats.

We use appropriate materials and technique; Epoxy resins and adhesives are used throughout as these are impervious to water. Most production rudders are built using polyester resins and fillers as a cost saving measure. Unfortunately polyester is not waterproof, has poor bonding properties, and is prone to osmosis and water ingress. Not a good thing in a rudder.

Production rudders often utilize open cell foams such as “pour-foam” and a variety of other materials in the core, even saw dust and blocks of scrap wood! None of which are as good as the closed-cell foams (Corecell, Divinycell) that we use exclusively at CSI. These foams are stronger than other types of core material and resist water ingress much more effectively.

For the skins we use either E-Glass or carbon fiber, depending on which is appropriate. Fiberglass is resilient and less expensive than carbon but is a little heavier.

A perfect option for most cruising boats. If saving grams is a priority carbon is the obvious choice.

Replacement rudder blades are built in female tooling which allows us to keep the skins on the very outside of the blade for maximum strength. Little or no fairing is required once the blade is out of the tool. The fibers in the skin laminate are smooth and uninterrupted. Blades are cured under vacuum and post-cured at high temperature for strength and are absolutely straight and symmetrical. Once cured they are bonded to either the existing rudder post or a new one custom made to your specs. We treat the exposed interface of the post and blade with an extremely tenacious and flexible adhesive to prevent water ingress.

Finally the rudder will receive a bit of fairing if needed (not likely), receive a final epoxy barrier coating, a coat of primer and a final sanding with 220 grit sandpaper.

Your boat is the next stop!


Your new rudder/post combination will be reliable, offer increased performance, and a much higher safety factor than the stock original. This in turn will add value to your boat and even more importantly will give you peace of mind. If you are ready for an upgrade or repair call us!