Old Foil, New Foil
Transom-hung rudders on seasoned fiberglass cruisers are notorious for leaks and trouble, but there’s good news: They can be rebuilt.
A DIY couple rebuilds a waterlogged rudder.
PROJECTS
Rudders on good old hard-driven, classicplastic cruisers always seem to leak, and it’s been our practice to drain them whenever possible. So when our 1975 Kaiser Gale Force 34, Kraken, arrived in New Jersey after a roadtrip delivery from Florida, we drilled a hole near the bottom of its transom-hung rudder.
After drying out for a year on the hard, it still oozed black, nasty-smelling stuff.
Kraken was largely in good shape, but the passage of time and the hard environments of salt water in various climates— from the Canadian Maritimes to the Caribbean—had worked to split the seam between the rudder’s two thick fiberglass sides. This had been awkwardly repaired, and the lower of two massive castbronze pintles, which connect to gudgeons on the transom, was cracked. Though we were anxious to get Kraken in the water and finally go sailing (this was the second time we owned the boat), we decided to first rebuild the rudder over the coming winter.
Morgan Marina on central New Jersey’s Raritan Bay has a well-run boatyard with a crack boathandling crew. With the tiller removed, we connected ropes to the pin that throughbolts it between two stainlesssteel plates on the rudder, and the crane operator snagged the big hook into a loop. When he took up the weight on the crane’s cables, it quickly bent the ½-inch pin…and then snapped the rope. The waterlogged rudder was clearly too heavy to lift up, so we unbolted the remaining pintle and then let the crane swing it down on the sawhorses that my husband, Tom, had made. With the help of Bruce, another sailor, we used a Fein oscillating saw to slice open a section of the seam on both sides of the foil and made two cuts across the face so we could pry up a window. We had no drawings to show how the rudder had been built, so we were curious as to how it had been put together.
If this had been a spade or a skeg-hung rudder, the interior of it would have included the stock and its support structure, but a transom-hung rudder doesn’t have a post. Kraken’s had been built around thick sheets of end-grain balsa core glued together with heavy layers of thickened polyester resin. Bruce, a chemical engineer, identified the foul-smelling liquid as deteriorating polyester. For years, the rudder had apparently taken on water that couldn’t migrate through the balsa and past the solid resin to the drain hole. The freezing of this water split the seams.
The rudder was constructed in halves, and if we were to rebuild it again, we would separate it into two whole pieces. Working without drawings and knowing how important it would be to retain the shape’s integrity, we hoped to cut just a single big window in one side, dig out the wet balsa and replace it. Unfortunately, the sogginess extended everywhere below the waterline. Our initial progress was slowed by having to locate and cut a number of stainless-steel bolts that connected the fiberglass halves before we could pry them apart.
By the time we’d reached all the wet balsa, we had five separate pieces of skin, all cut with the Fein saw, on one half of the rudder, plus one uncut side and a solid glass trim tab whose attachment points had probably contributed to the leaks. Once the rotten wood was removed and most of the resin gouged out with big screwdrivers and various types
The project completed: The rudder on our Gale Force 34, Kraken, is now ready for many more miles of service.
of crowbars, the pieces were light enough to load into a van and take to our backyard, where Tom set up a portable garage and continued to remove balsa and resin until the inside was clean. He then used a random orbital sander to clean old bottom paint off the outside surfaces.
We now had two issues in choosing what to sandwich between the fiberglass skins. One was the core material for the replacement of the balsa; the other was making an armature to ensure structural integrity. Kraken’s 11-foot-long rudder is less than 2 feet wide for much of its length, but we still felt that it needed some lateral strengthening between layers of core. An obvious choice was to use Coosa proprietary structural panels made of high-density polyurethane foam reinforced with layers of fiberglass. Coosa, however, is available only through distributors, and the handling and shipping costs for the amount we needed were prohibitive.
Instead, we decided to replace the balsa with the 16-pound, two-part Expanding Liquid Urethane Pour foam from US Composites (uscomposites.com) and make an internal stiffener of epoxy-soaked plywood. It took between one and five layers of ½-inch marine plywood to build the stiffener from a paper pattern drawn by Tom, each coated with unthickened epoxy resin (US Composites 635 Thin Epoxy System with medium hardener). The layers were glued with the US Composites epoxy thickened with West System 406 Colloidal adhesive filler and screwed together.
Next, Tom used a router to smooth the edges to remove any sharpness, and then covered the whole foil with fiberglass cloth and three coats of the unthickened epoxy resin. The finished armature was quite heavy, but we figured that much of the extra resin that filled in around the balsa in the original core—especially the solid layers in the foot—served to add weight to the old rudder. The armature was fit into the intact bottom shell, leveled, and then epoxied in place directly to the rudder skin. The foam was mixed and poured around its edges and through 1½-inch holes that had been rounded and epoxied.
Once the rudder’s intact half was filled with foam, Tom started reassembling the top half. First, he reattached the lowest piece (which had been removed to access the old resin packed into the base) using West System 610 Thickened Epoxy Adhesive (westsystem .com) to tack the skin in place.
He poured the foam with the rudder tilted so that it would fill the base, then proceeded up the rudder, reattaching the next section. He mixed the foam in small batches and added it through 1½-inch holes cut with a hole saw near the top edge of each piece of skin, then tilted the rudder so foam flowed down and came out holes in the lower part. It was an iterative process, and tricky to keep ahead of the foam’s cure time. If voids do remain (and hopefully they don’t!), the foam won’t soak up water.
When all the pieces had been tacked in place and filled and the rudder was whole again, Tom ground down and taped the surface joints using 1708 biaxial fiberglass cloth, which combines woven roving on one side and mat on the other, then coated the cloth with the unthickened epoxy resin, making for a durable finish. He saved the plugs from the rudder skin and replaced them after cutting away any cured foam that stood proud, then taped and epoxied them. Where cracks showed workings of the original fiberglass at the pintle cutouts, he added extra plywood and resin, overdrilled the bolt holes, and filled the area with thickened epoxy to isolate the bolts from the core. He paid special attention to taping and epoxying the seam between the two halves. We weren’t replacing the bolts that ran between the sections in the original rudder, but the new treatment of the seam was stronger than the old, which had not been taped but merely filled, and so it split easily when the core froze and swelled. The entire rudder was faired with Totalfair, a Totalboat marine epoxy fairing compound (totalboat .com). It was sanded, and then barrier-coated using Interlux’s Interprotect 2000E (interlux .com). Above the waterline, it was painted with two-part Interlux Perfection Topside Finish; later, the bottom will be coated with bottom paint.
The rebuilt rudder is still heavy but considerably lighter than the waterlogged original. A new pintle is being recast.
Rebuilding a transom-hung rudder turned out to be a surprisingly straightforward process. We are looking forward to reattaching the rudder and seeing how Kraken responds to it.
Ann Hoffner and her husband, photographer Tom Bailey, sold
Kraken this summer after completing this rudder rebuild. They bought a Sabre 30 to coastal-cruise in Maine, where they now live. Previously, they cruised for 10 years on their Peterson 44, Oddly Enough.