Reply To: stern tube cutlass bearing replacement advice needed

Hi Alastair. Thanks for using the forum. It does work. My boat Ocean Swan, has needed replacement bearings several times. The bearings themselves are supplied either in a bronze tube case or in a non metalic tube case. The idea being that some stern tubes might react badly to the bronze shell. Either would be ok for your stern tubes. They also come in different lengths. I think yours are likely to be about 10 or 12 cm long. (4 inches or so). You have spotted the grub screw hole in the stern tube which holds the bearing tube in place. It is likely to be an allen key head. You will have to dig around to find it. It is possible it has fallen out. You will need to take out the prop shaft, then having removed the grub screw, remove the bearing. This is sometimes difficult. There are special tools a mechanic would use. You need a longish heavy bar that will go up inside the bearing, this might have a sturdy washer screwed into the end of the bar. The washer will also go in behind the bearing and drop down behind it. Then with some bumping and heaving your bearing should come out. The mechanics tool will have a heavy weight on a slide bar that he can bang against the end stop to release the bearing. Its now clean up time and insert the new bearing. It will need to have a countersink hole drilled gently into the bearing tube to accept the retaining grub screw. So dry fit the bearing and mark the spot. remove, drill and refit. I like to leave a little lip of the bearing sticking out of the stern tube when fitted. This allows you to put a bead of sikaflex or similar sealant to the outside edge to help keep the bearing in place. Don’t put sealant inside the tube or you will never get the bearing back out! The small lip of bearing I leave sticking out as described will alow you to get a grip on next time and you may be able to change the bearing without removing the prop shaft.

Hope all that helps, Geoff Linter