How do I replace the cutless bearing on an Albin Delta 31?

To replace the cutless bearing on your Albin Delta 31, you will need to remove the propeller, extract the retaining grub screws from the P-bracket, and use a mechanical press tool to push the old unit out over the shaft. You will likely need a metric 25mm internal diameter bearing with a brass or phenolic shell, which usually costs around £45 to £60 from brands like Vetus or Countrose.

Confirming Correct Bearing Size

Before buying parts, measure the shaft with digital calipers. Most 1980s Albin Delta 31s feature Yanmar 2GM20 or Volvo Penta MD7B engines driving a 25mm stainless steel shaft. The outside diameter of the bearing housed in the bronze P-bracket varies. Expect either 38.1mm (1.5 inches) or 40mm, with a typical length of 100mm. Brass shells often have dimensions or a part code stamped on the aft face of the flange. For phenolic (fibreglass and resin) shells, measure the internal bore of the P-bracket once the old bearing is out. Alternatively, measure the old bearing directly. Order a nitrile rubber bearing. A Vetus RM series or a Countrose unit will last a decade.

Removing Propeller and Screws

You must remove the propeller to slide the old bearing off. Remove the split pin. Undo the prop nut. Use a dedicated three-jaw prop puller. Never strike the propeller hub directly with a hammer. The shock wave travels up the shaft and destroys the gearbox thrust bearing.

Once the shaft is bare, inspect the sides of the P-bracket. You will find one or two grub screws locking the cutless bearing in place. These 6mm or 8mm Allen screws hide under layers of antifouling. Scrape the bronze clean. Clear the hex sockets with a pick and unscrew them. If they seize, apply heat from a butane torch directly to the bronze bracket surrounding the screws. This breaks the corrosion so you can back them out.

Extracting the Old Bearing

With the grub screws removed, the bearing is ready to come out. Removing the entire prop shaft from the gearbox coupling takes hours. Pressing the bearing out over the shaft in situ saves time.

• Buy a cutless bearing press tool, or build one using M10 threaded rod, heavy nuts and steel spreader plates.
• Use a split collet or a steel pipe cut in half lengthways. This must exactly match the outside diameter of the bearing to push against the forward end of the shell.
• Position a larger piece of pipe over the aft end of the P-bracket. This acts as a receiver for the old bearing.
• Tighten the nuts on the threaded rod to press the bearing out backwards.