Failure Analysis of a Jet Boat Steering Linkage

  • A. L. Beardsley
  • M. V. KralEmail author
Case History---Peer-Reviewed


As part of a steering linkage mechanism in a jet boat, two D-ring shackle pins were safety wired together in order to prevent either of the shackle pins from falling out. Relative movement of the D-ring shackles from maneuvering the boat caused fluctuating stresses in the stainless steel safety wire, resulting in a fatigue fracture of the wire. Without the constraint of the safety wire, a pin from one of the D-ring shackles became dislodged, resulting in the failure of the steering mechanism, loss of control and crash of the boat. As well as a demonstration of the key features of the components that led to the determination of a fatigue fracture, the significant flaws in the installation and configuration of the steering linkage are discussed.


Fatigue Safety wire Steering linkage 



The authors would like to thank Nicholas Breeuwer (postgraduate student at University of Canterbury) and Matthew Owen-Eales (Maritime Officer, Maritime New Zealand) for many helpful discussions.


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Copyright information

© ASM International 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringUniversity of CanterburyChristchurchNew Zealand

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