Sharp clunking noise from steering

[searocket]

Returning from Netherlands recently we were getting occasional sharp clunking noise from the steering area. The clunk noise typically followed by a second clunk noise several seconds later. Then quiet for 15 or 20 minutes and then repeated.
At the time there was a short sea in 20knots wind against tide and the boat was rolling a moderate amount going downwind. And we were on autopilot (Raymarine ST6001/M81130 linear drive)
We have a 34' sailing yacht with a spade rudder, the lower rudder bearing is a self aligning type.

There is no obvious play in the rudder or steering itself. There is a small movement where the linear drive is attached to the hull and the shaft attaches to the rudder quadrant.

Any suggestions on what would cause this noise and if it indicates a problem

 

[Graham_Wright]

Is your steering rod or wire?

 

[searocket]

the wheel steering is rod linkage to a quadrant on the rudder stock

 

[Boater Sam]

Rudder blade out of bed?

 

[penfold]

Need to sit in the locker watching it and induce the clonking, locating where clonks/random noises is often very tricky.

 

[MAURICE]

My boat occasionally makes clonking noises when heeled over. Its the chains linking the wheel steering to the rudder quadrant they sometimes touch the side of the steering binnacle. ive owned my boat 15/16 years now and has done this when going into the wind in choppy seas healed over.

 

[jdc]

Was the clunking when hand steering or only under autopilot? Autopilot actuators frequently have significant backlash which makes quite a clunk but isn't a sign that failure is imminent.

 

[RupertW]

You may have a rod or steering wire going and out of position when pushed by the drive, eg out of one of the pulleys, maybe more likely a worn rudder bearing so the vertical column wiggles as the rudder turns. As others have said you need to look at what’s happening.

 

[searocket]

thanks for the replies.
We have only noticed the noise under auto pilot, (on passage we almost always use the auto pilot).

 

[RupertW]

thanks for the replies.
We have only noticed the noise under auto pilot, (on passage we almost always use the auto pilot).

In that case it could still be the rudder bearing when the autopilot pushes the quadrant but could also be the bolt coming loose that attaches the autopilot to the quadrant. Have a look underneath when it’s making the noise.

 

[Graham_Wright]

the wheel steering is rod linkage to a quadrant on the rudder stock

I had an incident sailing to the Channel Islands where the steering became intermittent. It seemed that some cogs in the drive train were slipping out of contact. There were four gearboxes transmitting the wheel rotation to the quadrant. On inspection, it seemed each of them were jumping a tooth. This was an optical Illusion. The culprit was tracked down to the third in the chain.

 

[saxonpirate]

Could well be rudder bearings. I had a very similar experience on my old Beneteau First 35. Noticeable in a quiet swell the rudder would lift and clonk. With sideways pressure on the rudder it would sometimes make a noise but less heavy, and usually two/three knocks in rapid succession. It turned out to have two causes.. a worn thrust washer, and worn top bearing. Not a great deal of wear either, but enough to let you know something wasn't quite right..

 

[Gsailor]

Autopilots are great until they start to fail.

Why they use plastic cogs is for cost reasons I suppose- metal ones - bronze etc would be good, but then so many people say their autopilots are not waterproof... is that why manufacturers use plastic?

I used to treat my autopilots as if they were not even splash proof.

Hope you sort the noise out - at least you can rule out killer whales - they would be quite difficult to control.

 

[RupertW]

Autopilots are great until they start to fail.

Why they use plastic cogs is for cost reasons I suppose- metal ones - bronze etc would be good, but then so many people say their autopilots are not waterproof... is that why manufacturers use plastic?

I used to treat my autopilots as if they were not even splash proof.

Hope you sort the noise out - at least you can rule out killer whales - they would be quite difficult to control.

The kind of autopilot the OP has is entirely internal so will never get splashes unless something goes spectacularly wrong with the boat.

 

[Halo]

I had this on a brand new Bav C50 which I chartered in Turkey this spring. A chain on the steering was slack and it dangled down and pulled off the power steering actuator assembly. Fortunately I was close to base and it only took took a couple of hours to fix (mainly re drilling and screwing the assembly on. )
Get in there and sort it !