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Displacement measurements on propeller shafts

Displacement measurements on propeller shafts

Displacement measurements on propeller shafts

  • Input=___ rpm / ____ KW
  • Italy

Scope of work:

GBS Gearbox Services was invited by XXX to perform displacement measurements on the propeller shafts of the recently built M/Y XXX.

The M/Y XX was built by XXX yard in Livorno, Italy, as one of several vessels of the same design. On all of those vessels, vibration problems are experienced. When sailing at a speed of over 13.5 knots, a 4.2 Hz vibration is observed at several locations at the hull. Investigation of this problem was already initiated by the yard, leading to several propositions of possible causes. One of those propositions pointed towards the propeller shafts as a vibration source, possibly exciting one of the natural frequencies of the hull.

To investigate the behavior of the propeller shafts, a sea trial was organized. During this trial, the propeller shaft displacements where recorded using a set of two Bently Nevada 3300 series proximity probes per shaft. This way, the complete two-dimensional movement of the shaft could be monitored, at a location were vibration amplitudes were expected to be considerable. The vibration data was recorded using a Bently Nevada ADRE 208P data acquisition unit.

Location - date:

Italy - October 2009