Seaspan investigates retrofits with DNV GL

09 Nov 2016
Seaspan and DNV GL have investigated efficiency gains through retrofits by analysing data from the ship owner's containership fleet

Seaspan and DNV GL have investigated efficiency gains through retrofits by analysing data from the ship owner's containership fleet

Seaspan has worked alongside DNV GL in a series of projects which are aimed at investigated possible efficiency gains through retrofits.

It believes that despite low fuel prices, energy efficiency is a key differentiator for shipping companies competing for cargo.

Ian Robinson, project manager of the technology and development department at Seaspan, said: “We are constantly trying to improve the performance of our fleet, in order to meet current market requirements. DNV GL’s dedicated service for retrofit projects, based on computational fluid dynamics (CFD), formal optimisation and high-performance computing has made them a valued partner for us.”

DNV GL analysed two years’ worth of operational data to identify the ideal parameters for Seaspan’s 13,100 teu vessel and look at how it could be adjusted to minimise its yearly fuel consumption. It condensed this data into to twelve representative clusters of speed-draft-combinations with associated weights reflecting their time share in operation.

“Slow steaming is the easiest and most effective way to save fuel but the fact that this approach has become so widespread means that large parts of the existing containership fleet operate in off-design conditions, where engine, hull – especially the bulbous blow – and propeller performance is not optimal,” said Karsten Hochkirch, head of fluid engineering department, DNV GL. “For these ships, retrofitting bow and propellers which have been adjusted to suit their new operational realities, makes a lot of sense.”

The positives and negatives of retrofitting a bow and the propeller individually or together were examined during the project. It was discovered that the new bulb alone would have led to 6% of fuel savings, while the optimisation also resulted in a slimmer new design with 40% less area and 20% less weight. This leads to expected savings of 7.5%.

Hochkirch concluded: “In these retrofit projects, generally the sum is larger than its elements. An optimized bow leads to reduced power requirements and a better inflow. These in turn allow for additional propeller improvement. In this case, retrofitting both the bow and the propeller led to combined savings of 18%, which was confirmed in independent model tests.”

A further project between Seaspan and DNV GL, carried out on an 8,500 teu container vessel, led to combined savings of 14%.

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