Roller Bearing Rudder Upgrade: A DIY Guide for Spade-Rudder Sailboats

Upgrading a spade rudder from nylon bushings to precision roller bearings is a major project, but this step-by-step account from a Cal 40 owner proves it's within reach for any careful DIYer.

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CAD model detail showing modified tube end, 3D printed fairing piece and modified PET-P thrust washer. (Illustration/ Tom Egan)

Have you ever been sailing along and thought to yourself, something just doesn’t feel right. That is what happened to me with our steering on Misirlou, our ancient but venerable 1964 Cal 40. Like the proverbial frog in the pot of water heating up on the stove, the tightness and hard spots came on gradually, without me noticing at first.

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Tom Egan
Tom Egan is an engineer, inventor and lifelong sailor who cruises and races out of his home port Marblehead, Mass on his Cal 40 Misirlou, and just about any boat that will have him.

4 COMMENTS

  1. Very cool and nicely done.

    In contrast, I made new rudder bushings for my F-24 from trimmed PVC pipe bushings ~ 7 years ago. Still very tight and smooth. It turned out the original bushings were very, very close to a 1 1/2- x 2-inch pipe bushing, including the flange dimensions, and just a little fine-tuning with a drum and disk sander created a perfect fit. I can steer with my pinky, and there is zero play. I could have turned something on the lathe, but it would not have been any better, in this specific case.

    PVC is not a perfect bearing material, but it is used for this, they were oversize (2-inch rudder stock on a well-balanced 1500-pound boat), it is slippery and wear-resistant enough, and resists sunlight better than some alternatives. (They are exposed when the rudder is tipped up–the cause of failure was UV damage to the flanges, not wear. The rudder stock was not worn.) PVC does not swell in water (nylon, for example, can be a problem in that way).

    Food for thought, for smaller boats. I would have done something more like the article for my cruising cat. Very nice.

    • Great resourcefulness using PVC for the bearing swap! PVC isn’t known for great wear resistance (see https://www.azom.com/article.aspx?ArticleID=4101) but should offer many years of service. You are absolutely correct about nylon swelling as it absorbs water. I had nylon bearings because that is what was supplied with the rudder group-buy. Every season, just after launch, the rudder would bind-up from surface swelling of the bearings. A week later, when the full volume of the bearing was hydrated, the steering would free up again. Jefa uses PET-P for their wear surfaces.

  2. Excellent project and well written article.
    Tip for using peel-ply on odd shapes: Cut and laminate many small overlapping pieces, as if bird feathers or fish scales, instead of larger sheets. Tall-ish trapezoid shapes work well in the transitions from flats to tubes or conical shapes. Be sure to leave dry edges on the peel ply for a grip to peel.