BOATS AND CANALS

The boat yard where we keep the boats belonging to Accessible Boats is saying that if we have to replace the prop shaft and stern tube then we should replace the stuffing box too. Any thoughts? Cheers Graham

Have they given a reason why? I certainly would want to know before committing to having any work done.

We had to replace the same on Hadar this year, the reason was that where the stern tube screwed into the boss (the boss is the part that is welded into the hull) was leaking, and having to replace the stern tube also meant the prop shaft had to be replaced, which also meant that the stuffing box and rear bearing also had to be changed. With the stern gear it is very much the case that if one part of it needs replacing then it all needs replacing.

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Regards
Keith Lodge

Sorry I should have replied to this earlier. The boat yard just offer us advice (probably included as part of there fees to 'support' our boats!) We end up doing the work. Reading your reply it seems to say that the stuffing box has a rear bearing in it. Is that correct? In which case it start to make sense!

Cheers Graham

No, there should be a separate bearing, in between the stuffing box and the UV joint of the prop shaft.

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Regards
Keith Lodge

Keith,
Your comment must be for the "older" installations, modern gearbox have the thrust bearing built in..

I certainly do not have a separate bearing between the UV joint and the stuffing box.

Hadar was built and completed in 2007, and the gearbox is a PRM. If there is no bearing between the stuffing box and the UV joint then any strain is taken by the stuffing box, not a good idea. Probably a shortcut taken by the builder to save money.

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Regards
Keith Lodge

Interesting, my own boat has an Aquadrive to transmit the thrust onto the hull and to act as a UJ it dates from 1991. Dawn was built in 1998 and has a flexible coupling between the prop shaft and engine and that is that. Cheers Graham