Stern Tube leak

[Max Nankervis]

Does anyone have experience of a cracked stern tube. At first I thought it was the dripless Volvo driveshaft boot leaking (a constant drop by drop leak). at the wide end where it is clamped around the stern tube. But I now think there is a hairline crack in the stern tune - about 1.5-2cms long, just aft of the boot. I can see the water being forced out as shaft spins.


Beyond drilling out the whole tube, and replacing it somehow, any cheaper suggestions?

[Pete7]

Does the crack go all the way to the inboard end of the tube and under the shaft seal?

I would be tempted (in fact I would) use epoxy and GRP cloth to make a bandage around the tube assuming you have access. Grind back where the seal fits if you have to glass this bit too.

However, I would also be wondering how it happened. Someone a bit clumsy previously fitting the prop shaft? or over tightening the Volvo seal clamp? seems unlikely. Worth checking the prop doesn't touch the stern tube with the engine running at low revs and cold so it shakes about a bit and at high revs when they lean over too.

Pete

[Max Nankervis]

Thanks. The crack is hairline and in the section of the tube as it emerges from the fibreglass, before the rubber boot (a space of about 4cms). Glassing it has been suggested (after grinding/cleaning off), though only the top half of the tube is visible/accessible, the rest embedded in glass.
As for the cause - probably old age and corrosion (35 yrs!). And yes, the vibration at idling speed would help.