How to Find, Drain and Reseal a Wet Sailboat Rudder

Walk around the rudder as soon as the boat is on land and again over the next few days. Practical Sailor's telltale sign is rust-colored water weeping from the joint where the stock enters the blade. Weeping can also show at pinholes along the thin trailing edge or at the bottom. Note where, how much, and the color: clear water means the core is wet, rusty water suggests the metal inside is corroding.

Tap the whole blade lightly with the handle of a screwdriver, as Epoxyworks did, and mark dull or "dead" sounding spots with a marker. Those are usually delaminated skin or waterlogged core. Also look for:

• Cracks, especially near the stock and along the top and trailing edges
• Bulges, blisters or split seams between the two halves
• High readings on a moisture meter, compared with the dry hull nearby

If the rudder has been removed, a wet one is often far heavier than you expect.

Grab the trailing edge and try to move it side to side and up and down, and turn the wheel or tiller while someone watches the blade. Movement between the blade and the stock (the blade lags or rotates while the stock turns) is serious: Practical Sailor describes a rudderstock that spun inside its blade after the internal webs rusted away. Do not sail until a yard has checked it. Rudder failures can sink boats: BoatUS's summary of the 2024 Bermuda Race safety reports describes a race boat whose crew heard a loud clunk, lost steering, found the rudder stock adrift and a large breach at the lower rudder bearing, and had to abandon ship. For bearing wear and the rudder tube, see the rudder bearings guide.

• Small weeping, solid blade, no play: drill to drain, dry over winter, seal in spring (steps 5 to 10), and keep an eye on it.
• Rust-colored water, cracks, big delaminated areas or any play: drain now to prevent freeze damage, but plan a proper rebuild or replacement (step 12).

Epoxyworks did exactly that on a Cal 33: a quick drain and seal to get through one season, then a full repair the next fall.

Gravity does the work, so the first hole goes at the lowest point of the blade. Practical Sailor adds two catches: water that entered at the top may not reach a hole at the bottom if the foam blocks it, and water tends to collect along the stock and the webs, so you may need holes where you think the webs are. Sand off a small patch of bottom paint at each spot. Keep well clear of where the stock runs inside the blade. If your builder or owners' association has a construction drawing showing the webs, use it.

Set a depth stop so the bit goes through the fiberglass skin and just into the foam, not into the stock or webs. Epoxyworks used 3/8-inch holes on the Cal 33. Hold a container under the hole and look at what comes out. Practical Sailor notes that on its test boat, the holes kept weeping on and off all winter, so do not expect a gush and then nothing.

Epoxyworks lists the options from simple to best:

• Gravity: a hole at the bottom drains most free water and should lower the moisture enough to prevent ice cracking.
• Sun: outdoors, tape a black plastic bag over the rudder. On sunny days it warms the blade above freezing and adds drying days, even around 25°F.
• Heat: a heat lamp aimed at the blade (never close enough to scorch it or anything nearby), or a heated shop if the rudder is off the boat.
• Vacuum bagging: the most efficient method, done with the rudder off the boat in a controlled space. It lets water boil off at low temperature. This is advanced or shop-level work.

Check the holes when you visit the boat. Keep them open and clear of ice and debris. If new cracks or bulges appear after a hard freeze, take photos and talk to your yard before launch.

When the holes have stopped weeping and the area is dry:

• Countersink (chamfer) each hole and sand the chamfer with 80-grit paper, as Epoxyworks did.
• Wipe with acetone and let it flash off.
• Fill with thickened epoxy (Epoxyworks used a ready-thickened epoxy adhesive; Practical Sailor used epoxy with microballoons), smooth it with a plastic spreader, and let it cure.
• Sand fair, then apply barrier coat and bottom paint to match.

Practical Sailor found that one hole kept pushing the epoxy out during the heat of the day, because warm air inside the blade expanded, then drew it in during the cool evening. If a hole keeps weeping or the epoxy will not cure, try again in the cool of the evening when the rudder is drawing air in.

Practical Sailor mentions an alternative: tap the hole for a small brass or bronze plumber's plug, set it in sealant each spring, and replace it every fall. Its advisor column notes that on a thin rudder skin the plug will stand proud of the surface. Some owners prefer drilling the same spot each fall and filling it each spring.

If you can reach the joint where the stock enters the blade, clean it out and apply a bead of flexible marine sealant, as Practical Sailor suggests. On many boats the gap is too tight to work on with the rudder in place. Also check gudgeon bolts and any old repair patches, which Epoxyworks found was the actual entry point on the Cal 33. See the marine sealants guide for choosing a flexible, removable product.

Plan a proper repair (usually with the rudder removed) if you find:

• Rust-colored water year after year, especially in salt water, where corrosion of the webs and welds is more likely
• Any play or slipping between the blade and the stock
• Large delaminated areas, deep cracks or a split along the seam
• A rudder that is still soaking wet after a full winter of draining

Epoxyworks describes the shop approach: remove the rudder, cut away the delaminated skin, dry the core (vacuum bagging worked best), check the stock and internal metal for corrosion, then relaminate with epoxy and fiberglass. In their example the repair cost a fraction of a new rudder. If the webs or welds are badly corroded or the stock is bent, a new rudder or a professionally rebuilt one is the safer choice.

A second Epoxyworks case shows what a full core replacement involves, so you know what you're asking a shop to do: the rudder looked fine except for a crack around the stock, but sounding with a hammer gave a dull note on both sides and test holes showed the whole foam core was wet. The repairer cut windows in the skin, chiseled out the foam, dried the shell, treated rust on the internal plate, filled it with new expanding foam, and rebuilt the skins with tapered (beveled) fiberglass laminations. It is a multi-day, multi-skill job. A crack around the stock is a common first sign that it may be needed.

Signs that the bearings or bushings need attention too, from Practical Sailor's rudder restoration article: play you can feel in the tiller or wheel, vibration at certain speeds, or a slap or thud from the rudder when you tack or jibe. Have those checked while the rudder is off (see the rudder bearings guide).

Write down the date, where you drilled, how much water came out and its color, and how you sealed it, with photos, in BoatMend. Comparing year to year tells you whether the rudder is drying out or getting worse.