The eight retrofits shipowner E.R. Schiffahrt undertook recently, supported by class partner DNV GL, were a full success: the measures included new bulbous bows, energy efficient propellers, engine modifications and cargo boosting.
DNV GL evaluated the vessels’ energy efficiency based on CFD calculation results, test reports and technical documentation to determine fuel and power savings for a given operational profile. This data was cross-checked with information gathered over a representative period before and after the retrofit.
DNV GL acknowledged the shipowner’s initiative by presenting E.R. Schiffahrt with the newly created Modification Excellence Award. “E.R. Schiffahrt has made a sustained and firm commitment to increasing the efficiency of its operations. Our analysis shows these ships use 15 per cent less energy, resulting in annual savings of approximately 3.8 million US dollars ,” said Jörg Lampe, Senior Project Engineer at DNV GL. The classification society’s advisory services have a long track record with E.R. Schiffahrt, having jointly planned and executed retrofits of more than 25 vessels over the past few years.
Reederei NSB has implemented similarly ambitious retrofitting measures within its fleet, including the spectacular widening of a container vessel. The 4,860 TEU ship is currently being upgraded to 6,200 TEU in a five-month conversion project at a Chinese shipyard. In a first step the vessel is cut in half lengthways. By adding three container rows the beam will grow from 32 to 39 metres, increasing the cargo capacity by 1,340 boxes. An optimized bulbous bow designed to reduce wave resistance will further improve the ship’s efficiency. As NSB’s classification partner, DNV GL is overseeing this unique high-tech project which NSB hopes will result in better employment and higher charter rates for the vessel. The owner expects a return on investment within three to four years. The current capacity enhancement contract includes two sister ships in the NSB fleet, and negotiations are underway to apply the same measures to several additional vessels, says NSB.
According to Dr Jan-Henrik Hübner, Global Head of Shipping Advisory at DNV GL, in terms of retrofitting ship - owners have come a long way since last year: “Contrary to FLEET INVESTMENTS PERFORMANCE 29 01/2015 MARITIME IMPACT Every ship type has optimization potential. The Efficiency Finder offers perspectives on boosting performance. The rendering shows the widening concept for panamax containerships. Last year, nobody you ask about retrofitting today will seem taken aback. Many shipowners have decided in favour of retrofitting in the meantime. Assuming an average period of about nine months between the decision to retrofit and the implementation, there are quite a few retrofitting projects in progress at the moment.
” Bulbous bow retrofits are among the most common measures. DNV GL has supported bulbous bow optimizations on 150 containerships of the global fleet of 4,500 vessels so far, Jan-Henrik Hübner estimates, so there is still plenty of potential. The investment pays off: assuming an average cost of 600,000 US dollars for bow optimization and a six per cent reduction of bunker consumption, the payback period will be around twelve months (given bunker costs of 600 US dollars per tonne) respectively two years at today‘s oil prices. In the experience of DNV GL, retrofits have a direct positive impact on charter rates, reducing consumption claims by charterers.
DNV GL’s calculation tool Efficiency Finder provides an overview of specific retrofitting measures. It outlines the level of applicability for selected ship types and helps owners assess payback times and pre-planning. For more information visit the Energy Efficiency finder page.
This rendering shows the widening concept for panamax containerships.