It is essential for the innovation, transformation and industrial reform of the domestic shipbuilding industry to overcome the design challenges of large Liquefied Natural Gas (LNG) ships and thus solve bottleneck technologies. However, the large LNG ships generally adopt the design of double shafting with double shafting lines of inward inclination angles. This unique design results in an extremely complex flow field at the stern of the ship with increased lateral forces on the shafting, adversely affecting the safe and stable operation of the shafting. The calculation method for the shafting alignment is studied thoroughly by examining the hull deformation, propeller hydrodynamics and bearing oil film thickness of a large LNG double shafting ship. This method more truly reproduces the actual operating state of the shafting, improves the safety margin of the shafting, and obtains a forward-looking, feasible and stable calculation scheme for the dynamic alignment of the double shafting.

Energy efficiency is the main direction of innovation in today’s shipping industry. In particular, the Ship Energy Efficiency Design Index (EEDI), which came into effect by IMO on January 1, 2013, has pushed energy efficiency innovation to a whole new level. Since the introduction of marine shaft generator in the 1980s, it has been gradually applied to large container ships after successive major changes and innovations. However, there are no application case of shaft generator on a full-scale Very Large Crude Carrier (VLCC) due to the limitations imposed by many factors such as space and speed. The world’s first VLCC equipped with the shaft generator is optimized with consideration of the influences of the shafting torsional vibration equipment, bearing load distribution, machinery space layout and stern shaft extraction, etc. The shaft system of the VLCC is optimized and designed from three aspects of shafting arrangement, shafting torsional calculation and shafting alignment calculation. A feasible, efficient and forward-looking low-cost optimization design scheme of the shafting is then obtained by adjusting the number, material and diameter of the shafting, and the height of the main engine.

Affected by the global warming, resource crisis and trade protectionism, energy conservation and consumption reduction, transformation and upgrading, and innovation and development are the only way for the development of the shipping industry. The International Maritime Organization (IMO) launched the ship energy efficiency design index (EEDI), which came into effect on January 1, 2013. The entry into force of this resolution has a large impact on the selection of the power point of the ship main engine. Operators have chosen to reduce the power of the main engine to meet the EEDI requirements. However, the acceleration performance of the main engine will be significantly reduced when it is operated with the reduced power. Therefore, the barred speed range (BSR) cannot be passed through quickly, resulting the great threat to the safety of the shafting. A theoretical analysis of the decrease of the acceleration performance has been carried out for the main engine at the BSR to find solutions from the main engine control system, propeller design and shafting design. The results are finally verified with the calculated results that the ship can meet the requirements of the various classification societies while operating safely and stably.