From 1st July 2002 Tailshaft Monitoring (TMON) became a class notation. The TMON rules are not retroactive. For vessels with class request after 1st July 2002 the rules will be included in the class certificate.

Newbuilding
TMON will normally be included in the class request. Documentation subject to approval will then be requested for the ship and approved accordingly. Once the documentation is approved by DNV, the newbuilding station will perform an implementation survey. Provided the survey is successful, TMON will be added to the class certificate as an additional class notation. DNV will provide a TMON record file and oil-in-water test kit for record keeping onboard. The attending surveyor will review the file during annual survey (no fee charged).

Ships in operation
All applications concerning ships in operation should be sent to the DNV Head Office, Machinery Ships in Operation department or to a local DNV station. A vessel that had the last tailshaft withdrawn more than three years ago must submit satisfactory monthly records for the same period covering issues that include:

• Bearing and sea water temperatures
  
• Oil consumption
  
• Water content in oil
  
• Bearing clearances from last dry-docking
  
• Wear-down measurements after last shaft withdrawal.

If the above cannot be confirmed, TMON might be implemented after shaft withdrawal combined with a complete tailshaft survey.
For more information contact: mtpno376@dnv.com