Blocks with plain bearings

When plain bearings are the right choice

Ball bearings run more smoothly under load – that's true. Plain bearings excel where blocks are rarely or unevenly loaded, where dirt and salt can penetrate the bearing, or where simply little maintenance is desired. Typical applications include fixed deflection points, Cunningham systems, boom vangs, or positions where the rope is not permanently under tension.

What to consider when choosing

Three things are crucial: the breaking load of the block in relation to the forces encountered, the sheave diameter to match the rope diameter of your sheet or line, and the mounting method – whether fixed eye, swivel, snap shackle attachment, or direct mounting on a track. A sheave diameter that is too small significantly increases wear on the rope.

Material and construction

Most plain bearing blocks for sailing have housings made of fiberglass-reinforced plastic or aluminum and sheaves made of acetal or similar plastics with good sliding properties. The plain bearing itself is often integrated directly into the sheave – no separate component that can fall out or corrode. This makes them lower maintenance than ball bearings, but not maintenance-free.

Daily care

After the season or after prolonged use in heavy weather, it is worthwhile to disassemble the sheave, remove salt crystals and dirt, and lightly lubricate the plain bearing with a suitable lubricant. Stay away from oil- or grease-based products that can damage ropes – dry lubricants or specific block cleaners are the better choice.