- an alternative to the normal thruster survey scheme

Vibration monitoring of a thruster by the crew and DNV during an implementation survey.

A new alternative to the normal thruster survey scheme based on condition monitoring for propulsion and DYNPOS thrusters has been launched by DNV. The new scheme will reduce the scope for the intermediate survey and thus not require internal examination of the underwater part of the thruster housing. This means in practical terms that DNV will not require the docking of a vessel for intermediate thruster survey as long as the results from the condition monitoring are within acceptable limits.

Called Thruster CM, the new survey scheme is based on analysis of regular vibration and oil analysis carried out by
the crew. The results shall be analysed and documented and relevant actions shall be taken when required.

In order to obtain approval of this condition monitoring alternative, the following process applies:

• The technical manager of the vessel applies for a Company Approval for use of condition monitoring along with required documentation.
• Upon completion, a certificate will be issued allowing the manager to request an implementation survey onboard.
• The implementation survey is carried out onboard in order to establish a baseline for the condition monitoring measurements, and to verify that the procedures that are approved are followed up. Based on a successful implementation survey onboard, the vessel is approved for Thruster CM.

Upon completion of the approval process, an annual survey is carried out to verify that the arrangement is followed up according to the rules.
Reference is made to DNV Rules Part 7, Chapter 2, Section 2 H and Classification Note 10.2 Appendix H.