Study Case of Marine Propulsion Shaft Measurements by the Strain Gage Method: before and after a ship hull grounding accident

Abstract

The strain gage method for propulsion shaft bending moment verificationhas been in use since the 80’s. In this work, the authors present theirprocedure and results of this method to an Anchor Handling Tug Supply(AHTS) ship. The method was applied in this ship in two occasions: afterdelivery in 2018 and after a grounding accident in 2019. After a period ofhull repair, the bearing reactions were verified at the same time by Jackupand Strain Gage methods. The results by the Strain Gage techniqueare considered more accurate and complete than those of the Jack-up.Based on the Strain Gage results, it was concluded that the groundingaccident caused a change in the alignment of the shaft lines, mainly onstarboard side. The comparison between the methods presented thesame graphic shape, however the Jack-up measurements differed fromthe Strain Gage ones at some points due to some factors noted anddiscussed by the authors.