Intermittent knocking ( from rudder ? )

[buttonfreebie]

I have just been reading about rudder bearing replacement and methods for tightening the top nut with various C spanner configurations. A couple of comments state that the rudder can be tightened by giving this not half a turn. Surely the rudder shaft should not move up or down unless the steering quadrant nuts are slackened.

[Yngmar]

There is quite a bit of space for the steering quadrant to move up and down in its bracket, at least 5mm, so for minor adjustments that's fine.

After 1500 miles our top nut had slipped a little (despite the locking screw compressing the threads) and the quadrant was squeaking on the bottom of the bracket, which was soon fixed by tightening up the top nut to bring it back to where it should be.

So tighten up the top nut, see if your quadrant has enough room between top and bottom of its bracket and if any of this cures the knocking. It's quite possible it won't - maybe your bottom bearing is worn and needs replacing.

[geoff]

I also have an 40 ocean and found after 15 years ownership heard an intermittent knock from the rudder generally when the rudder was unloaded [light winds ] I tightened the top nut with a homemade peg wrench and then relocked the nut. That was 2 years ago no more noises Geoff

[Moodymike]

is it possible to overtighten the top nut and cause the steering to stiffen?

[buttonfreebie]

Thank you for your comments. I will try to just tighten the nut and see what happens. Interesting to note the movement available in the quadrant. I have already made enquiries with Jefa about a replacement bearing just in case . They have one available for either a 63 mm or I think 78 shaft. Price 165 euro ex vat and shipping. Ida is in Rhodes and will come out of the water at the end of October,so work will start then to check on the bearings thoroughly.

[buttonfreebie]

One more comment ...this knocking is only intermittent and only when under engine and there is some swell. I suspect a combination of turbulence from the prop and the swell. No problem under sail

[sunshine]

Check the draglink ball joints for movement up and down on the pin that goes through their centre. If the balljoints don't rotate freely, they can wear the pin causing play which then creates a clunking sound as the wheel or rudder moves back and forth. Just grip the draglink halfway along and move it around checking for play. If none, great - just grease the balljoints while you are there.

[Lyra]

One more comment ...this knocking is only intermittent and only when under engine and there is some swell. I suspect a combination of turbulence from the prop and the swell. No problem under sail

Are you sure noise comes from the rudder (or rudder mechanism)? - I would take a look at the flexible exhaust pipe in the lazarette - it loops upwards as a syphon and down to the exahust port and secured to the bulkhead/body with a band or two - it they get detached the pipe occasionally knocks on the bulkhead when under engine (happened to me - took me some time to find the reason)

[buttonfreebie]

The rudder is now removed and there is no apparent problem with the bearings. The lower one had been replaced with a Jefa roller bearing but the top one is original . I plan to replace the top bearing with a Jefa.bearing .I would have liked to replace the top bearing housing as I can detect some wear but will wait until i have the new bearing to check the amount of play ,if any.
I did discover after lifting out that the Propeller had been moving back and forward .Indicating a failed rubber bush .The rope stripper had worn about 4mm off the face of the prop and the locking cone had worn into the opposite end .End result a new prop !
 .Also some bright spark had tried to fit the rope stripper which was obviously off the previous saildrive onto the new 130s sail drive  .
I now need to fit a new anode designed to house a new half of the stripper together with new stripper bearings.
I will check on the exhaust support when I am back in Rhodes in January. Thanks for the tip.
Merry Christmas to all !

[Salty]

One more comment ...this knocking is only intermittent and only when under engine and there is some swell. I suspect a combination of turbulence from the prop and the swell. No problem under sail

Are you sure noise comes from the rudder (or rudder mechanism)? - I would take a look at the flexible exhaust pipe in the lazarette - it loops upwards as a syphon and down to the exahust port and secured to the bulkhead/body with a band or two - it they get detached the pipe occasionally knocks on the bulkhead when under engine.....

Lyra has a very valid point, I noticed the same knocking noise on a friends B37 while motorsailing in the Irish Sea between Whitehaven and Douglas, and a year or two later on my own B36. In both instances there was a moderate sea running, and with the boat pitching gently the motor was loading and unloading as the prop either got buried deep or lifted close to the surface. However, in both instances there was no noticeable vibration on the steering which might otherwise have suggested a rudder or steering problem. Going into the lazarette to investigate what was causing the noise resulted in some concern as the vibration was, as Lyra's said, down to heavy vibration in the exhaust hose where one of the securing points had separated from the GRP structure within the lazarette. On my friends B37 the movement of the exhaust hose was sufficient to give rise to concern that if something wasn't done about it immediately, that there was a risk of the exhaust hose becoming detached from the hull skin fitting in way of where it connected to overboard outlet. The danger here being that the boat could flood from the water in the exhaust system and that the hull could fill with carbon monoxide gas..

[Moodymike]

Had the same thing on my B32 (2003). Two supports had broken away.