Section 1 General requirements

1.1.1 This Chapter applies to azimuth or rotatable thruster units, for propulsion or D.P. duty which transmit a power greater than 220 kW used as the sole means of steering and are in addition to the relevant requirements of Pt 5, Ch 19 Steering Systems.

1.1.2 In general, for a ship to be assigned an unrestricted service notation a minimum of two azimuth thruster units are to be provided where these form the sole means of propulsion. Where a single thruster installation is proposed as the sole means of propulsion or steering, a detailed engineering and safety justification is to be evaluated by LR. This evaluation process will include a risk assessment analysis using a recognised technique to verify that sufficient levels of redundancy and monitoring are incorporated in the azimuth thruster’s essential support systems and operating equipment.

1.2.1 The following additional plans are to be submitted for consideration together with particulars of materials and the maximum shaft power and revolutions per minute:

• Sectional assembly including nozzle ring structure, nozzle support struts, etc.
• Shafts, gears and couplings.
• Steering mechanisms with details of ratings.
• Bearing specifications.
• Schematic piping systems.

1.2.2 The declared steering angle limits are to be stated by manufacturer for each azimuth thruster.

1.3.1 Where Thruster Condition Monitoring (ThCM) ShipRight descriptive note has been requested, refer to ShipRight Procedure Machinery Planned Maintenance and Condition Monitoring, Section 8.