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Old 23-08-2013, 01:30   #1
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rudder wobble

Hi
Swimming under Sephina yesterday I decided to wobble the rudders to check for movement. Port felt good, no movement, but starboard moved a bit. The rudder goes into a collar fits inside the hull. The collar was moving along with the rudder. I would estimate 3mm movement, for/aft and athwartship. As it moves I can hear it knocking. Is this normal. Is there a way to adjust it and what is the next step to confirm if there is a problem.
Sephina has never touched the seabed.
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Old 23-08-2013, 01:50   #2
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Re: rudder wobble

Monte,

there are plastic inserts in the rudder bearings which wear over time. I had all 4 replaced while the boat was out last year - it's not expensive, and it fixes the bearing play.

Oliver
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Old 03-09-2013, 05:33   #3
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Re: rudder wobble

Thanks Oliver, will do next haul out!
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Old 07-09-2013, 11:00   #4
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Re: rudder wobble

sendt you a mail Monte.
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Old 07-09-2013, 11:27   #5
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Re: rudder wobble

Last season i replace 8 set of bushings and bearings in both Lagoon catamarans, the lower metal collar is glued with 5200 , and the top one is delrin, be aware that in some Lagoons there is a flaw in the design of the rudder post arm, to short, and the long alu tube is making a lot of sideways force in the rudder shaft , wearing the top delrin bearing in short time, the top delrin is a piece of cake to remove and install, the lower is glued with 5200 with the rudder in place , if your starboard rudder is moving at the bottom is probably due the caulking fail and the collar is loose , you need to clean very well all the rest of caulking , sand a bit with probably 100 grit sandpaper , clean with acetone , sand with 80 grit the metal collar side where it made contact with the rudder post and aply 5200 .... Hope this help.
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Old 07-09-2013, 13:41   #6
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Re: rudder wobble

If one is wobbling while the other is not, one of them has an issue.

I know the standpipe is not supposed to wobble, neither is the bearing. The rudder shaft may have some free play inside of the bearing, if the bearing is slightly worn.

If everything is relatively new, I would suspect some one used one metric and one imperial bearing BUT the differences never amounts to 3 mm.

Ergo, your 3mm are well wort further investigation.

How did it feel last time you were on dry?

You have a tech drawing of that part? Images from boatyard perhaps?

b.
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Old 07-09-2013, 14:08   #7
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Re: rudder wobble

The 3 mm gap come from the caulking be gone, im 100% sure, when the metal bushing start to turn with the rudder the caulking is washed and there is some mm diference between the FG tube and the metal collar, this mm need to be sealed with 5200 or Sika...Cheers.
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Old 07-09-2013, 16:08   #8
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Re: rudder wobble

Quote:
Originally Posted by neilpride View Post
The 3 mm gap come from the caulking be gone, im 100% sure, when the metal bushing start to turn with the rudder the caulking is washed and there is some mm diference between the FG tube and the metal collar, this mm need to be sealed with 5200 or Sika...Cheers.
I hope others will correct me where I go wrong.

3 mm gap is just too much (?) locking the bearring in place with a sealant is new to me. I think maybe the OD of the bearing is simply some 2.8mm to small?

All the bearings I have seen this far were mechanically locked (tight fit + locking bolt, etc.).

???

Are you positive the bearing is fixed inside the tube with an adhesive/sealant and 3mm of it?

Looking forward to other owners input.

b.
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Old 07-09-2013, 23:36   #9
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Re: rudder wobble

I cant tell you if Lagoon fit the bearings with glue or somekind of plexus stuff, the bottom one is not mechanically fited in any way, im 100% sure , maybe new lagoons are diferent, both boats here in the boatyard come with rests of 5200 around , in both boats when we drop rudders at least one side the rudder come with the bushing dancing around the shaft, in the other side we found the bushing still atached to the tube with 5200, but look, yesterday come here a L440 with the keels , rudders , and bottom almost destroyed by hiting hard a reef, ruders are in the ground , and one of the ruders got the bushing atached to the shaft.... i can take a pic tomorrow maybe and post it.

Now one guy here tell me a good trick to help the bushing to grip better in the tube with the caulking, simple as to use a dremel and cut some shallow lines in the outward side of the bushing, one every 1 inch, like that the 5200 have a better grip in the bushing and can last longer, another guy say use epoxy , i dont think is a good idea, so basically the better stuff is 5200..in my opinion.

Here is a pic ...
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Old 08-09-2013, 01:58   #10
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Re: rudder wobble

Thanks guys, I'm pretty sure its as Neil and Careka suggested. The metal ring in the tube needs 5200 to take up the space. Easy fix and I'll do it in a few weeks when we haul out.
A good explanation and detailed pics on this page as well
Why knot?: Grenada Marine - Trading Views...
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Old 08-09-2013, 06:05   #11
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Re: rudder wobble

Beneteau has the same on the Oceanis boats, and there manual say it is glued with
P-400 , and that the opening in the brass collar is to be 1 mm..
But look at it when you are out of water, it is easy to se how it has to be.
------
i fix it on our old B.O.411, and the rudder looks the same as on L380.
Simpel and easy fix.
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