Blue Opal has been developing a low grumble/rumble when the engine is running under load. The suspicion was that the cutless bearing was deteriorating, because the engine itself sounds very smooth, and there’s no grinding in the gearbox.

Finally got her lifted over at the local yard this week, mostly to clean and anti-foul the hull, but also to investigate the state of the cutless bearing and to replace it if possible. Alas, it turns out it’s not going to be possible in the near term. Electrolysis has taken hold, and the Vetus (VS25 as I read the stamp on the side) stern gear assembly has been weakened, while simultaneously bonding the cutless bearing to the stern assembly.

Starboard view, old wrench marks showing

It also turns out that this particular assembly was brazed on to the stern tube at manufacturing time (confirmed by Vetus), so it cannot be twisted off for easy replacement. In the process of investigating the assembly, the top bolt cap disintegrated completely, so only the bottom one is holding the left side of the assembly to the right side. This can be mitigated with an epoxy for the moment.

Underside of the assembly

The grub screw hole doesn’t look very good either, dezincified and generally in bad shape. The current decision is to put things back together, use a metal epoxy to secure the top bolt, finish the cleaning and anti-fouling work, and do investigation in to how I can get this repaired/replaced. The local yard doesn’t have space in their calendar right now, and has also said they’ve not worked on this kind of setup before, so research is needed on how to deal with it.

Cutless bearing troubles
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