After a rather lengthy prop removal, I finally started unscrewing the cutless bearing holder on Offcutt only to find it didn't unscrew from the stern tube, instead the stern tube started unscrewing from the forward end mounting plate. Since this point is inaccessible (enclosed in glassed over ply) on Offcutt, I stopped unscrewing as soon as I realised what was happening, fearing that it might be very awkward getting that forward end back in the right place on replacement. I think a bit of polysilphide (it is polysulphide not Sika, I know because I did it two years ago) may have 'sealed' the cutless bearing holder to the stern tube. The shaft is still in place. Does anyone have a trick for holding a very short length of exposed stern tube to stop it from rotating? Or am I worrying unnecessarily, the forward end will reconnect just fine when the time comes if I do remove the stern tube and separate it from the cutless bearing holder on the bench?
The cutless bearing, as supplied by our dear friends at T Norris two years ago, is already excessively worn after only two seasons in South Coast waters, about 200 hours in all, and needs replacement. I remarked at the time I fitted it, along with a new shaft, also supplied by our dear friends, that it seemed sloppy even before installation, but was told it was fine. I have it in mind to use Vesconite (I already have a suitable blank that just needs final machining), a high tech plastic bearing material which is so high tech the bearing only needs to be 1 inch long (but can of course be longer, as Offcutt's will be). Has anyone used Vesconite? Any tips? If not, I will give it write up here once I have fitted it and then again after it has been in place for a season (or until the next lift out). It could be very useful for Twisters with limited cutless bearing lengths, as some have, and it is not expensive if ordered directly from the manufacturers in South Africa.
Hmmm, Interesting question.firstly do you have a real Cutless bearing or a thin wall bush?
I’m pretty sure that the owners of Brigand Chief (about 3 back) used the magic material and were well pleased with it. It was written up in the magazine at the time and you should, with a little patience, be able to find it in the archive.
My next thought is that if the inboard end of the tube is not sealed to the inboard carrier which also carries the stern gland then you will be most likely to have a leak down the threads into the bilge. This may be enough to be more than annoying! I know, we had the same. I don’t think that the glassed in carrier is a good idea. Ours was bolted in place and relatively easy to remove and deal with by cleaning and joint sealing the threads on reassembly.
Our outboard bush is a thin wall Tufnol one which has been in place for over 30 years. We fitted a large screw down greaser and the whole tube is full of grease with a trace exiting the after bearing. Purveyors of stern gear express horror at this but for us it works (and they get no money)!
John — thanks for your reply. I've managed to track down the Brigand Chief article — you have an amazing memory! — it is from the Nov 2001 issue, in the Technical Topics section, and sure enough the material was Vesconite. I wonder if the lack of any subsequent reports (that I could find) amounts to 'no news is good news', ie the Vesconite behaved well? I also wonder if the current owner of Brigand Chief has anything to contribute on the matter?
Offcutt's current cutless bearing is definitely a standard brass shell cutless bearing. It and the shaft are both Imperial (I didn't make that mistake!). I was rather surprised the inboard end of the stern tube started unscrewing, rather than the cutless bearing housing unscrewing from the stern tube, which is what happened last time I took it off, two years ago. My hunch is that the polysulphide the housing is bedded on also got pushed into the stern tube/housing thread on assembly and has glued it enough to make the inboard end of the stern tube the less stuck end, which is why it unscrewed. It may also be relevant that I also worked on the inboard end (refurbishing the stuffing box) and I may have somehow inadvertently feed it off a bit, though it hasn't leaked as far as I know in the two years since I did the work. But then I might not know, because the whole area is glassed in! The inboard carrier plate is only bolted in place, but it is bolted to a glassed in partial bulkhead about 10 inches (?) from top to bottom, with the void aft of the partial bulkhead that the stern tube passes through closed off top and bottom by glassed on panels. Rather tricky to describe in words, I will try to find or take photos. Access is further limited because the fuel tank is above the the boxed in area, with only enough clearance to allow the fuel lines to pass through. The other worry I had, which hasn't so far materialised, is the nuts for the bolts that hold both the cutless bearing holder and the inboard carrier plate are not well glassed in place, and so fall off as I put the bolts back in place.
If I do end up removing the stern tube, I should be able to clean up the inboard end thread (there is a lot of grease in the area so it will need cleaning) and thinking about it, the the stern tube thread is male, then the inboard carrier plate thread must be female, which means if I remove the shaft and stuffing box then I should be able to make a stab at cleaning that too, and then add some polysulphide on reassembly. But a bit of me says if the inboard end wasn't leaking before (so far as I know) despite being loose enough to unscrew, then maybe it won't leak if reassembled 'as was'. Now I know why I am glad I started doing this in January, rather than two weeks before the boat is due to go back in the water!
Edit 21 Jan 2026: having slept on it, I now think if I do have to remove the stern tube, or maybe I should do it anyway, to get a seal at the inboard end, then the best way to get a seal is to use PTFE tape. Doing so avoids the need for spotless cleaning which polysulphide needs, and if I use the thicker type of PTFE tape, I should be able to achieve a seal doing it blind, by feel rather than under direct vision. I can always do a couple of test runs to confirm the PTFE tape ends up properly embedded in the threads.
Problem solved! What I thought was the stern tube turning was in fact part of the cutless bearing holder that projects into the stern post turning. I was looking at some old photos of the stern gear to see if I had any of the inboard end to show how it was all enclosed apart from the mounting plate (impossible to photo now as too much other stuff in the way eg cockpit drains) and came across some of the outboard end that reminded me of how it was all put together. With that in mind, I just carried on unscrewing the cutless bearing holder and off it came, leaving an undisturbed stern tube including its inboard end still in place. Phew!
And an update…..
Today I spoke to the 2000 partnership owner of Brigand Chief. By his recollection the Vesconite, which they machined themselves, performed well and the bearing was still good when she was sold some 6 or so years later. I actually saw her being surveyed then and there were certainly no issues with the bearing.
To digress a little ….. On our stern tube the inboard bearing is White Metal. When we re-engineed we discovered it to be massively worn. As we had already decided to fit a Halyard Aquadrive unit we did not re-metal the bearing but set up the Aquadrive accurately to carry the inboard end of the shaft in good alignment. Years on all is still good.
John
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