MAN Bags Danaos Shipping Propeller Order

MAN Diesel & Turbo has won the order to supply Danaos Shipping Co. Ltd. with fixed pitch Kappel propellers, propeller boss caps with fins, and Engine Power Limitation for two container vessels – the 8,500 TEU ‘CSCL Europe’ and ‘CSCL America’.

Mr. Dimitrios Vastarouchas, Technical Director & Deputy Chief Operating Officer of Danaos said: “At Danaos we look forward to have the vessels upgraded. Our R&D Department has conducted very thorough investigations before concluding what the right upgrade solutions for these vessels are and we are confident that the vessels will be highly competitive in the market once upgraded”.

Both container vessels are powered by MAN B&W 12K98MC-C main engines rated at 68,520 kW at 104 RPM. In connection with the propulsion upgrade the main engines will be limited to 44,000 kW at 89.7 RPM however; top speeds of more than 23 knots will still be available.

Along with the upgrade of their propulsion systems, the vessels will also enter dock to rebuild their bulbous bows. Combined with the already installed Turbo Charger Cut Out these comprehensive upgrades are expected to reduce fuel consumption at the new optimization speed of 18 knots by a total of more than 15% compared to the vessels as they were delivered from the new building shipyard in 2004. The upgrade packages will make the Danaos container vessels among the most competitive mid-size container vessels in the market.

Vessel & Engine Specific Study
Most mid-size container vessels were often originally designed and build to operate at much higher speeds than it is the case today and accordingly, their propulsion characteristics can be optimised.

To this end, MAN PrimeServ’s Retrofit & Upgrade Departments in Copenhagen and Frederikshavn started up a ‘Vessel & Engine Specific Study’ in 2015. The project researched 12 different potential solutions for optimising propulsion using diverse MAN Diesel & Turbo technologies and products individually and in various combinations. Concurrently, Danaos ran some 35 concept studies on the optimisation of its vessels at their in-house R&D department before concluding on how to proceed.

Before the final choice of solution was made, exhaustive CFD-simulations and model tank tests were also carried out at the Krylov State Research Centre (KSRC) in St. Petersburg, Russia.

Besides verifying the performance of the new Kappel propellers and the new bulbous bow design a primary reason for carrying out model tests was also to ensure that the new propellers for the CSCL Europe and CSCL America would have the correct light running margin (LRM). A temptation with optimisation projects can be to deliberately reduce the LRM below the optimal in order to give the propellers a slightly higher efficiency. Ultimately, a propeller layout with a reduced LRM will however be at the expense of the engine’s SFOC whereas the full potential of the propulsion upgrade will not be exploited in full scale.

Instead, the philosophy at MAN Diesel & Turbo is to avoid looking at individual components alone and to look at the complete propulsion drive train in a holistic fashion where components are viewed in terms of the mutual influence they have on each other.
Apart from the new Kappel propeller and propeller boss cap with fins – both designed for the reduced engine output – the container vessels will also, while in dock, have their bulbous bows altered to a design that better matches their future operation profile – an operation popular known as a ‘nose job’.