Cutless Bearing Replacement Discus and W33

The noticeable +/- 1/32" play in my Discus Cutless bearing was a surprise because it had been replaced professionally six months earlier by the previous owner. The Surveyor suspected engine alignment or rough prop shaft surface.

                                                                                      Prop and Cutless Bearing Before

Prop Shaft Removal The Discus and W33 Cutless bearing are of the same design and are basically a larger versions of the Centaur arrangement. The procedure for Cutless bearing replacement is as described in Centaur Cutless Bearing Removal and Replacement. More heat may be required to free off the Discus/W33 prop. Hot water wouldn't do it for me but a short application of an oxy acetylene torch did the trick instantly.

                                                                                   Cutless Bearing unbolted and unscrewed from shaft tube

                                                                                      Severe Prop Shaft Damage is Evident inside bearing

So new prop shaft and new cutless bearing is indicated. Prop shaft, prop and cutless bearing housing were dispatched to T Norris Ltd in Isleworth for replacement and refurbishment which took about a week. Package arrived back containing new slightly longer prop shaft (to accommodate rope cutter), new cutless bearing fitted to housing with allen key set screws in place of original slotted screws, nicely shiny polished prop and new deep sea seal.

To remove the prop shaft it was necessary to drop the rudder. This was quite straightforward but involved digging an appropriately shaped hole about 3 feet deep and lowering the rudder gently using two ropes looped underneath.

At the same time I took out the prop shaft tube by undoing the clamp at the support inside the boat and feeding it out of the hole left by removing the cutless bearing assembly.

The new cutless bearing was a nice tight fit to the new prop shaft.

On the W33 and Discus there is a bronze plate that fits behind the cutless bearing. The lower cutless bearing bolt screws into a hole tapped in the plate whilst the upper bolt has a clearance hole and a nut fixing.

I glued the plate in position using black sikkoflex to make relocation easier. Otherwise you may have to use a longer bolt to find the lower hole.

In the picture the shaft tube has yet to be replaced.