#1 2019-12-30 09:58:41

Marc_Langbroek
Member
From: Den Helder, Netherlands
Registered: 2019-03-04
Posts: 8

Replacing rudder bearing bushes.

Ls,

As I am in the process of replacing the bearing bushes of the rudder hinges for my Frances 26 "Grace Darling"  I am facing some challenges that might be solved easily with the help of some local expert knowledge. The members forum I hope is the place.

Matter is that for replacing the bronze bushes the whole bearing holder has to be removed, because the trajectory of the bush is in the way of the fasteners of the unit. The top and middle one are no problem, these are bolted thru the stern post, easily reached from within. The real interesting one is the bottom bearing holder. This one is fastened with two nyloc nuts on two threaded ends, who somehow are attached in the lower stern post, lowest corner under the propeller shaft bearing. A corner hard to reach. After removal it showed that from one of the two threaded ends the thread was beyond repair, i.e. useless. To make a reliable construction again, I'll have to replace the damaged end.

Question is: How are the two lower threaded ends fastened in the stern post? I tried to upload a picture in this topic, seems not to work.

Any suggestion is welcome,

Marc Langbroek,

Frances 26 "Grace Darling".

marc.langbroek@gmail.com

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#2 2020-01-01 18:31:52

Hugo_Motamelo
Member
Registered: 2016-12-24
Posts: 6

Re: Replacing rudder bearing bushes.

Mark,

I also would like to check these fastenings. In Boreas K, my Frances 26, they look allright with no leaks but a good check would do no harm.

I took some pictures of the interior of the keel, with poor quality, and I think the bottom gudgeon is fastened like the two others.

If that is the case I think the only way will be to make a very long tool to access the bolts with the help of mirrors, a very strong light and lots of endurance.

If the engine and diesel tank are out maybe things will be simpler.

Sorry for my english!

Happy 2020 with fair winds

Hugo Melo

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#3 2020-01-01 19:13:24

Marc_Langbroek
Member
From: Den Helder, Netherlands
Registered: 2019-03-04
Posts: 8

Re: Replacing rudder bearing bushes.

Hugo,

Thanks for the quick reply. I think we share the same points of view, i.e. the two lower fasteners are almost unreacheable. I tried yesterday with a Bosch endoscope, which gave some insights, but most of the time I was wriggling with the long scope cable trying to comprehend what I was seeing. I ended with a rather obscure view of  the lowest bolthead. The bold was fitted thru a wide washer with two folded sides as to secure it from turning around while being fastened.

So without removing  engine and fueltank I see little possibilities to replace them. I do now use the only protruding centimeter of thread thats workable to fit a threaded bush on it, widen the hole in the gudgeon and  then bolt it all together. Do use grade 416L stainless steel threaded bush to prevent it from rusting on the long term.

Another drastic measurement could be to open up the sternfoot from aside (outside), at the height of the fasteners of the lower gudgeon, and from there replace them. But that involves also some polyester repairs as well.

Success with the challenge,

Marc Langbroek
Grace Darling.

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#4 2020-01-02 23:20:00

Jonathan_Hopper
Member
Registered: 2004-03-23
Posts: 96

Re: Replacing rudder bearing bushes.

'The bolt was fitted thru a wide washer with two folded sides as to secure it from turning around while being fastened'.

I have puzzled these questions over the many years as well.

Is it possible that these washer looking things are some sort of captive nut?

Francesca has had several changes of bushes in the lower gudgeon over the years, usually by the yard.   There have been no nuts appearing in the bilge, and no nuts on the bottom gudgeon bolts (though I do have the washer looking things you describe).   It may well also be that the original bolts (M8?) that have at some point been changed the something bigger (M10?).   My only reason for thinking this is that one of the bent over washers/nuts has been pushed inboard.   I wonder if the 'bent over washers' are actually captive nuts, and also that for the last few years mine has been secured solely by the laminate.   The alternative is that it has always been secured by the laminate!

The laminate at that point is thick, and may well provide enough grip to secure the bottom of the rudder.   I have placed an extra block at the end of the keel so no rope can get between the hull and rudder, so there should be no extraordinary shock loads.   Keeping the laminate dry behind the fitting is useful.

The V800 has a different fitting, and I think if ever the engine was out it would be worth investigating whether sufficient filler could be put in the back of the keel to change to a similar arrangement as it does look easier to service, and perhaps stronger.

There may also be an 'engineering solution' to this - eg something like a riv nut.   However, whilst Francesca supports two bolt which are happily gripping in laminate it is not something that is high on the list.

On the subject of corrosion of the stainless bolt.   Presumably this is crevice corrosion?   The bolts holding the brackets in the rudder suffer from this and I draw them every couple of years to check, but the ones drawn from the laminate looked in good condition last time I had them out (though the previous must have been changed for a reason). Perhaps moisture had got in to the thread?   

Whatever you find with this, or whatever you decide to do, I would be very interested!

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#5 2020-01-03 09:58:38

Marc_Langbroek
Member
From: Den Helder, Netherlands
Registered: 2019-03-04
Posts: 8

Re: Replacing rudder bearing bushes.

Jonathan,

Thanks for the thoughts and the insights. Ill keep you posted on my findings. The bolds securing the brackets on the rudder blade came out rusty, due to the fact that the wrong grade s.s. was used. I.e. A2 , always go for A4.

Marc.

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#6 2020-01-09 22:43:22

Andrew_Gleadle
Member
Registered: 2014-09-23
Posts: 32

Re: Replacing rudder bearing bushes.

Hi Marc

I would also be very interested in your findings as I'm planning on stripping mine next winter (many other jobs this winter).

Like you I took some picture with an Endoscopic Inspection Camera (DropBox link: https://www.dropbox.com/sh/8wofabr8dam0 … 38ua?dl=0). It does appear the nut is held captive with adhesive and a bent washer or form metal. I haven't tried loosening the bolts on the outside but it looks likely the bolts on the inside would stay put.

Regards
Andrew

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#7 2020-04-20 20:55:31

Marc_Langbroek
Member
From: Den Helder, Netherlands
Registered: 2019-03-04
Posts: 8

Re: Replacing rudder bearing bushes.

LS,

The operation "rudder bush" has been completed in a most satisfactory way. I asked the webmaster to post some pictures with the article, so in advance I'll give a summary of my activities.

Replacing the rudder bushes is a periodical reoccurring event, which will announce itself by an increasing clinging from the rudder, especially in light weather. Inspection of Graces bearing bushes showed they were worn as well as the fingers of the hinge itself. So only replacing the bearing bushes was not going to deliver the desired effect, i.e. a smooth and silent running rudder. Hence the decision was made to replace the hinge pins as well.
Now the easiest part is the dismantling of the hinges from the rudder. The trickiest part is to renew the pins on the hinges. These three pins are aligned with the bearings on the stern post, and the greatest care has to be taken to recreate that alignment exactly as it was put together. Difficulty enriching factor is that the 3 hinges are bolted thru the rudderblade, and this is done probably 'on sight'. Also the hinges look like they were made in a batch, all a little different! So to be sure to get the alignment right, I took a piece of wood the thickness of the rudder and bolted the three hinges exactly in line with each other. I then grinded the hinge pins away, cleaned and grinded the rest of the hinges clean. I then welded a 10mm stainless steel rod in one piece over the three hinges. (Grade 316L, seawater resistent) and finally cut them short with the grinder. After giving the three pins a tapered beginning for easy handling and the upper pin a M10 threat, the hinges were ready to be replaced. Part of the bolds were from stainless steel A2 grade, that started to corrode away. I replaced them all with A4 quality.

The bearing bushes were taken apart with the bush holder complete for easy removing of the worn bearings. By heating the holder gently with a propane burner, the bush will come out easily. Use a copper rod to tap them out. I missed the fact that the lower bush was already a first oversize, probably in the past the hinge pin chafed all the way thru the bearing, and started to 'eat' the bush holder. So a oversize bearing had to be ordered. I also ordered a extra set of bearings for the future.
The bush holders were fastened with new A4 grade SS bolts and nyloc nuts, all protected by anti seizing compound. This to prevent the so called crashing or cold welding of stainless steel in stainless steel. The only point of care was the lower bush holder. The fasteners were partly deteriorated due to corrosion, and after some serious investigations, I found they are hard to reach for replacement. Or better, unreachable. . The challenging part is to replace them with new ones. Wether it be replacing the old ones one way or the other, or gluing new ones in position, I'm not sure. Long story short, I used the remaining useful treat to fix the bush holder in a satisfactory way. Thus for now all is fixed and I'm looking forward to the performance of the rudder.

Notice to d.i.y. engineers:
- Always use the right grade stainless steel, i.e. A4 for fasteners,  316L  for rods, sheet, strip or piping.
- Always use anti seize compound when using nuts and bolts, SS tends to crash when dry and tightening,
- Welding the hinge pins is a specialists job, the whole preparation can be easily done at home. Saves a good lot of money.
- Lifting the rudder out and placing back in can be done easily alone, just use a lashing strap around (over) the stern post and under the middle hinge. In that position the rudder hangs in balance and can be easily maneuvered.

small_gd_001_rudder_removal.jpg
small_gd_002_rudder_removal.jpg
small_gd_003_rudder_removal.jpg
small_gd_004_rudder_removal.jpg
small_gd_005_rudder_removal.jpg
small_gd_006_rudder_removal.jpg
small_gd_007_rudder_removal.jpg
small_gd_008_rudder_removal.jpg

Hope these notes are useful,

Marc Langbroek
Frances 26 "Grace Darling".

Last edited by Marc_Langbroek (2020-04-21 08:58:39)

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