Q&A: water through the stern gland
PUBLISHED: 16:29 22 January 2019
Help! I have an old narrowboat which lets in water through the stern gland
Q: I have an old narrowboat which lets in water through the stern gland. It will stop after greasing but definitely needs repacking as it has not been done for many years. It is also using a lot of grease. An engineer had a look and said the stern tube is worn and ideally would need replacing. Would I be able to repack using your notes and not replace the tube? We don’t use it that much and only do short cruises nowadays. I just wanted to know if re packing alone would help with water ingress for a few more years. - Stephanie Gilmir
A: TONY REPLIES: Unless the engineer stripped the old packing out the only thing that would allow him to say the gland or shaft was worn would be the gap around the shaft where it comes out of the front of the gland, or reaching through the weed hatch so he can assess lift on the prop shaft. He would have had to clean horrible black greasy gunge for the gland face to see how warn the hole for the shaft was.
If the hole in the end of the gland is oval, egg shaped, or it has a 1mm or more gap between the shaft and gland then repacking may not be a long-term solution because packing can get pushed into the gap and get chewed up by the rotating shaft. The same applies to the “bearing” at the back of the gland.
Of course you can repack it but you may find you need to adjust (not grease) the gland frequently thereby giving a short packing life. Even so repacking several times will be far cheaper than a new gland, rear bearing and probably the shaft.
Go for it. You can do it in the water but make sure the bilge pump is working well and above all work steadily and do not panic when you get water ingress. Cut the new packing rings BEFORE removing all the old packing, do not simply put a few more turns of new packing on top of the old.