How should I inspect and maintain sailboat rudder bearings?

Inspect rudder bearings each season for sideways movement, stiff or uneven steering, loose supports and water leaks, and check them more thoroughly whenever the boat is lifted. Identify the bearing and seal arrangement before lubricating it: many plain composite bearings run with water lubrication, while some metal bearings and sealed assemblies need a specified grease.

Identify the bearing arrangement

Find the boatbuilder's drawing or bearing manufacturer's instructions first. A grease nipple, packing gland and seal drain each need different treatment. Follow the rudder stock from the steering quadrant or tiller head towards the hull, locating the upper support, retaining collar, lower bearing and any seals or packing.

Common arrangements include:

• Plain polymer or composite bushes: usually need cleaning and clearance checks; use grease only if expressly specified.
• Ball or roller bearing assemblies: servicing depends on their construction, seals and manufacturer's instructions.
• Bronze bearings with a packing gland: check bearing wear, packing condition and gland adjustment.

The Island Packet 31, for example, has two bronze bearings. Its lower bearing also forms the packing box and uses ¼-inch square packing. The upper bearing has a locking collar above it and plastic thrust washers that carry the vertical load. This packing size applies to that arrangement; it is not a general rudder specification.

Check play and steering resistance

Ashore, ask someone to watch each bearing housing while you gently push and pull the rudder blade sideways and fore-and-aft. Apply force near the stock first, then farther down the blade. Movement at the blade tip magnifies bearing clearance, so tip movement alone cannot tell you whether a bearing is worn.

1. Watch where the stock enters each bearing. Distinguish movement of the stock inside the bearing from movement of the whole housing.
2. Check housing bolts, backing plates and surrounding laminate for looseness, cracks, rust trails or separation.
3. Check vertical movement and inspect the retaining collar and thrust washers for wear or displacement.
4. Turn the steering slowly through its normal travel, feeling for tight spots, scraping and changes in resistance.

Record any measured clearance at the bearing and compare it with the manufacturer's limit. There is no reliable universal millimetre allowance. If you cannot trace the stiffness, disconnect the steering linkage and test the rudder independently, then refit and secure the linkage correctly.

Before loosening a quadrant, retaining collar or bearing support, have the yard independently support the rudder against dropping.