Vibrations? Check your Rudders

2011 February 13
by Chris Brown
Shaft and Rudder Configuration on a M61' arlow

Prop, Shaft and Rudders on a 61' Marlow

The new owner and new Captain on a beautiful 61′ Marlow came into the yard.  The vessel had a major vibration that was most noticeable when driving from the lower wing station.

After removing props we went through our standard running gear inspection process – checking shaft run-outs, bearing clearance, seals and engine mounts.  The running gear all checked out within spec so no need to pull shafts and create a big bill.

The rudders were extremely loose with up to 0.125″ of play and slop in the tiller arm pins.  This was clearly a source of vibration with the prop wash rattling the rudders around.

Marlow’s were built using cutlass bearings as lower rudder bearings.  We believe that allows too much play and premature wear.  The lowers and uppers were replaced with Tides Marine UHMW bearings.  The machine shop re-bushed the tiller arms and made new pins for the tie-bar.  New Tides Lip seals and back together – all nice and tight.  We only traveled a hundred yards in the New River before the Captain declared the problem solved.  A month later he sent us the following update:

“Hi Chris,  Thought you should know that the boat is running better then the day we bought her, thank you. Less noise etc. And we can actually run over 1400rpm with out breaking plates. ”

Next time you have a vibration, try to listen closely to your rudders.  Don’t assume it is a shaft or alignment problem.  And make sure you use a contractor that will take the time to inspect before tearing apart.  We saved this owner a tremendous amount of money by recommending a “pass” on a full shaft job.

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