SIGHTING BY LIGHT METHOD (OPTICAL TELESCOPE)

 

Reference datums are selected at height of the shaft above the keel aft and the height of the crankshaft centre above the keel extended to the forward machinery space bulkhead (also centre athwartship) forward. These two datums are taken from the ship drawings.

The rough bore of the stern frame is fitted with a plate flange having a small hole of sight  holes  say  800 pm  max   error   16mm   le   1mm  per  say 40m  length elevation

SIGHTING BY LIGHT

telescope   micrometers   allow   variation  of  ±100 mm   on   perpendicular crosslines   but the  radial   markings  on the   telescope   which are graduated up to   25 mm diameter   allow   much  greater  misalignment  to be read directly from target  without  using   micrometers at all

SIGHTING BY OPTICAL TELESCOPE

SIGHTING IN SHIP

 

 

Bearing load method

Top cover off and horizontal alignment checked by measuring the side clearances of the shaft within the bearings. By using the system shown the shaft is carefully jacked up and a graph plotted. Initially a curve will be plotted as the ships structure stress relieves itself from the weight of the shafting, shaft still sitting on bearing material.

When curve assumes a straight line shaft has left bearing and in order to avoid damaging the shaft only sufficient plots will be taken to establish the slope of the straight line. The slope of the line for each bearing is put into a computer program which establishes the shaft system characteristic.

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