The annual Hellenic Technical Committee Meeting of Germanischer Lloyd (GL) discussed technical implications and commercial benefits of using gas as ship fuel. According to Mr. Torsten Schramm, Chief Operating Officer of Germanischer Lloyd, the global availability and low emissions make gas a more favourable source of energy for the main propulsion in shipping.
Natural gas is the cleanest of all fossil fuels. It already provides about a quarter of the total global energy. Furthermore, the combustion of natural gas results in lower levels of emissions. Given the fuel price development and lower emission limits, LNG is going to be an attractive alternative to distillate fuel in Emission Controlled Areas (ECA).
Prof. Apostolos Papanikolaou, Director of the Ship Design Laboratory, National Technical University of Athens (NTUA), and Dr. Pierre Sames, Senior Vice President Strategic Research and Development of GL, talked about the creation of novel ship design concepts with advanced optimisation environment.
As an example of this approach, Dr. Pierre Sames, presented an advanced new Aframax crude oil tanker design concept: It reflects the on-going trend to greener shipping by improving energy efficiency, reducing CO2 emissions per unit transport, and offers a smart solution by cutting fuel costs due to the optimized hull form and increasing cargo capacity. Furthermore, it addresses the need for safer shipping by reducing the oil outflow in case of an accident. It offers a best-in-class cargo capacity with unrivalled speed performance while the main particulars of the vessel are comparable with those of similar-sized Aframax tankers.
The Aframax tanker design approach used the most advanced optimisation environment by integrating software tools to predict required propulsion power, stability, oil outflow index, cargo capacity and hull structural scantlings according to IACS Common Structural Rules. The optimisation targeted speed at three different drafts, a cargo capacity taking due account of cargo volume and mass, hull structural mass, hull cargo, oil tank, ballast tank layout as well as double hull width and double bottom height, which determine the oil outflow in accidents, are the main features of this Aframax tanker design.
Related design parameters were systematically varied and approximately 2,500 design variants were generated and assessed. The resulting optimized hull form facilitates a speed of 15.6 knots at design draft. The speed requirements of ship operators are considered with regard to the upcoming Energy Efficiency Design Index (EEDI) requirement to ensure superior competitiveness of the vessel.
With this high speed and large cargo capacity, the vessel easily meets future EEDI requirements. The attained EEDI value is merely 83% of the latest published reference-line value for this ship size. This means the vessel would be in compliance with EEDI regulations even if the first reduction to the required EEDI has already begun. At current estimates, this will happen at the earliest on the 1 January 2015. Although a vessel contracted before EEDI has entered into force does not formally need to comply, competitive vessels entering the market, e.g., in 2017, will be more energy-efficient and therefore, more likely to attract cargo.
For safety reasons and to reduce oil outflow in accidents, the double hull side width was eventually set to 2.65m. In addition, to further reduce cargo tank penetration in grounding events, the tank inner bottom of the cargo oil tank 1 was raised. To ensure structural continuity, an inclined inner bottom is proposed between two frames.
The design study is based on a project by GL and the National Technical University of Athens (NTUA). Feedback from shipyards and oil tanker operators initiated the continuation of the project work which resulted in the novel design concept called BEST plus. BEST plus enhances the attractiveness of the initial design concept by integrating hydrodynamic optimisation of the hull form and state of the art features to improve energy efficiency on board.
Further topics of the Hellenic Technical Committee Meeting were the presentation of a practical guide to ship recycling. Jens Rogge, Lead Auditor for Ship Recycling, explained the requirements of International Convention for the Safe and Environmentally Sound Recycling of Ships. The so called Hong Kong Convention will come into force 24 months after the entry-into-force conditions were met.
The IMO convention on recycling covers three areas. These comprise the design, construction, operation and preparation of ships for recycling; the safe and environmentally sound operation of ship recycling facilities; and the creation of enforcement mechanisms for ship recycling, including surveys and certification, inspections and reporting requirements.
Shipyards will have to prepare an inventory of the materials used in the construction of a ship, which will have to be updated during the life of the vessel. Ship owners will have to prepare these inventories for ships already in service.
Last but not least, Athanasios Reisopoulos, Secretary of the Committee and Area Manager Southern Europe of GL, raised the attention of the Technical Committee members to the important role of preheating in welding technology with the use of new generation higher tensile finer grained steels. Welded structures are found to exhibit cracks, although the development mechanisms and also the possible countermeasures have been studied widely, but not always effectively implemented.
Preheating is a key factor of the welding procedures to be carried out by the manufacturers/ shipyards prior to commencement of welding works and therefore must be accurately calculated in order to produce satisfactory results. He further presented three widely recognised methods of calculations of preheating temperature and finished his presentation with practical examples of how preheating should be applied and measured in order to avoid cracking in the weld or heat affected zone.