Recent engine room design trends have resulted in propulsion shafting arrangements that are increasingly shaft alignment sensitive, with lower tolerances and margins. This sensitivity heightens the risk of stern tube bearing failures. The IMO’s Energy Efficiency Design Index (EEDI) also impacts vessel design, resulting in vessels with more efficient propellers that have larger diameters.
ABS Global Ships Systems Center Director Dr. Chris Leontopoulos gave a presentation entitled “Enhanced Shaft Alignment” at the Royal Institute of Naval Architects (RINA), Hellenic Branch on December 11th. His presentation centered on trends in shaft line design in post-EEDI vessels and updates to ABS Rules regarding shaft alignment, shaft alignment installation and verification procedures.
Dr. Leontopoulos also presented on the latest ABS Notations, namely the ESA (Enhanced Shaft Alignment) and ESA+ notations. He explained that these notations represent optimized designs while the Rules represent the minimum standards.
Participants included ship owners, operators, class societies and marine consultancy companies. After the presentation, the attendees held lively discussions and shared experiences on several varied, yet pertinent, projects related to shaft alignment. The attendees also congratulated ABS for its consistent worldwide efforts in reversing the previous upward trend in shaft alignment failures.
ABS has conducted pioneering work in technical areas such as: the Rule implementation of double sloped bearings; the requirement for hull deflections and final laser sighting; the consideration of the propeller loads on the shaftline curvature; and its innovative projects on Smart Bearing and Digital Shaft Alignment Monitoring (DSAM) systems.