In response to the market demand for very large CP propellers up to and beyond 30,000 kW and with diameters over eight meters, MAN Diesel is expanding its propeller portfolio to add two new, propeller hub-sizes – VBS2080 and VBS2240 (2080 mm and 2240 mm hub diameters respectively).
These propeller sizes are typically destined for ConRo vessels, shuttle tankers and special vessels with high ice classes, and powered by MAN B&W two-stroke MC-C or ME-C main engines that directly drive a CP propeller.
As the potential for improving propeller propulsive efficiency aft-ship optimization is far greater than that for improving diesel-engine fuel-oil economy, MAN Diesel has devoted more resources to its CP propeller program and associated aft-ship systems in recent years, with the aim of improving total propulsive efficiency by 8-10% within the next three to five years.
Backed up by industry demand, MAN Diesel focuses on low environmental impact and optimal fuel-oil consumption. While these two factors can play against each other in diesel-engine design, they go hand-in-hand with propellers since an increase in propeller efficiency results in lower propulsion power and fewer emissions.
Where the correct approach to the vessel-design process is taken and MAN Diesel are involved at an early stage in propeller and aft-ship optimization, propeller efficiency improvements and bollard-pull increases of (respectively) 5-7% and 8-12% can be attained compared to a standard, conventional, CP propeller solution. Such solutions offer even greater potential in retrofit projects where fuel-consumption reductions of up to 12.5% have been reported.
The new Alpha propeller hubs, like the smaller, well-proven ones, focus on reliability, low wear-rates and service-friendliness as they are serviceable from the aft-end, with no dismantling required.
Alpha is also the first CP market series where both the stern-tube system and propeller hub can operate on biodegradable oil, eliminating any risk to the environment and guaranteeing internal propeller lubrication, even in the event of seawater contamination.