EFFECT OF DOUBLE BOTTOM HEIGHT ON THE STRUCTURAL BEHAVIOUR OF BULK CARRIERS

This is the first of a series of companion papers that the authors propose to present on the effect that the new CSR Rules will have on the design of bulk carriers. Our initial focus will be on the new design framework established for the inner bottom height of such vessels, a parameter critical to their structural integrity. It examines the effect that double bottom height reduction has on the reliability of the bulk carrier structure, by applying a finite element 3D - 3 hold analysis of varying double bottom heights to a typical current Panamax bulk carrier design. The results are compared to pre and post IACS CSR[2] requirements. The conclusion reached is that the establishing of the double bottom height should not be left to direct calculations. A minimum acceptable height should be established in order to maintain a minimum level of structural reliability and safety.

TECHNICAL FEASIBILITY OF HYBRID PROPULSION SYSTEMS TO REDUCE EXHAUST EMISSIONS OF BULK CARRIERS

The combination of a prime mover and an energy storage device for reduction of fuel consumption has successfully been used in the automotive industry. In the shipping industry, the potential use of a hybrid battery-diesel-electric propulsion system is investigated. The scope of this study is to suggest that in existing newly built vessels and in modern designs, such a combination can be achieved without significantly affecting the principal dimensions of the ship and the cargo capacity. This work considers structural arrangements of a bulk carrier fleet of all vessel types. Complete calculation of free, void and machinery spaces is performed. The energy requirements of each vessel size and the derived energy storage system are used to inform the installation and construction scenarios. Meanwhile, trim constraints are investigated and discussed. Installation and retrofitting issues affecting the housing compartments of the proposed system are investigated for the current ship designs. Results indicate that such an installation will fit in modern bulk carriers and that proper allocation of the weight may be used to improve the trim. Cargo capacity is affected by less than 1.0% and is dependent on the battery weight, the type of diesel generators and electric motor technology deployed.

LIFE-CYCLE CO2 EMISSIONS OF BULK CARRIERS: A COMPARATIVE STUDY

The paper contributes a reasoned methodology and useful data to the debate that is taking place in the context of rational Goal Based Standards. It is hoped that the paper will generate further debate which should eventually lead to generally accepted conclusions on meaningful minimum design and classification rule standards.

OPPORTUNITIES FOR IMPROVED EFFICIENCY AND REDUCED CO2 EMISSIONS IN DRY BULK SHIPPING STEMMING FROM THE RELAXATION OF THE PANAMAX BEAM CONSTRAINT

In 2014 the Panama Canal Authority is scheduled to bring into commission new locks that will eliminate the long standing Panamax beam constraint of 32.2m. The expansion of the canal is aimed at increased capacity for container transits but will clearly have consequences for all types of vessel. There is an emerging demand for dry bulk carriers that are larger than the current Panamax limit of around 85,000 dwt but smaller than the Capesize class of around 160,000 dwt and the expansion of the canal will facilitate this development. Larger vessels will permit economies of scale and greater efficiency in the dry bulk shipping sector compared to what is currently possible with conventional Panamax ships. The relaxation of the constraint will additionally permit the development of more efficient hull forms than is possible within the existing beam constraint and the expansion of the Panama Canal’s locks will therefore (eventually) contribute directly to the reduction of CO2 produced by dry bulk shipping. The use of the Panamax constraint is far wider than the dry bulk sector, however, and the potential for reduction in carbon emissions for other sectors currently constrained to 32.2m beam is recommended for further study to evaluate the total carbon reduction ‘windfall’ that could result from the expansion of the Canal.

Estimating human error probability in transporting steel cargo with bulk carriers using a hybrid approach

Maritime operations include potential human-made hazards. For this reason, evaluating human-made hazards for cost-effective ship management is of vital importance in the maritime industry. From past to present, researchers have attempted to offer preventive approaches to minimise human-made hazards. In this context, the present article proposes a hybrid approach through the integration of the Delphi, Analytic Hierarchy Process (AHP) and Human Error Assessment and Reduction Technique (HEART) methods. With this approach, human-made claims occurring during the handling and transport of steel cargo in bulk carriers were analysed. The outputs of the present article contribute to the improvement of overall safety levels of steel cargo and bulk carriers by considering the potential hazards in risk management.

Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators

Topologically protected surface states present rich physics and promising spintronic, optoelectronic, and photonic applications that require a proper understanding of their ultrafast carrier dynamics. Here, we investigate these dynamics in topological insulators (TIs) of the bismuth and antimony chalcogenide family, where we isolate the response of Dirac fermions at the surface from the response of bulk carriers by combining photoexcitation with below-bandgap terahertz (THz) photons and TI samples with varying Fermi level, including one sample with the Fermi level located within the bandgap. We identify distinctly faster relaxation of charge carriers in the topologically protected Dirac surface states (few hundred femtoseconds), compared to bulk carriers (few picoseconds). In agreement with such fast cooling dynamics, we observe THz harmonic generation without any saturation effects for increasing incident fields, unlike graphene which exhibits strong saturation. This opens up promising avenues for increased THz nonlinear conversion efficiencies, and high-bandwidth optoelectronic and spintronic information and communication applications.

The Reliability Of Watertight Longitudinal Girders Of Fuel Tanks On Aging Bulk Carriers

During the exploitation of bulk carriers, the condition of structural elements and areas depends on the type of the cargo transported, operational conditions and maintenance systems. Corrosion significantly accelerates the aging of metal plates and girders thus causing the deterioration of steel surfaces, which consequently reduces the reliability of structural elements, areas and ships in general. The damage to metal structures can impair the stability of a ship, reduce longitudinal strength, cause the ingress of water into the hull as well as environmental pollution through fuel spills from the tanks. Therefore, the paper analyzes a part of a double bottom structure based on the available wear data on watertight longitudinal girders of fuel tanks. The research included 25 bulk carriers aged between 5 and 25 with the total of 110 fuel tanks. The reliability analysis of steel plates included the total of 1920 data measured. The allowable wear of structural plate thickness that equals 20% of the original thickness value was determined by the application of the acceptance criteria that were prescribed by classification societies. The calculations of the function of failure density, failure intensity and reliability determined the time when the condition of structural elements deteriorates due to corrosion up to the levels that require extensive maintenance services.

The Use of Artificial Neural Networks to Determine the Engine Power and Fuel Consumption of Modern Bulk Carriers, Tankers and Container Ships

The 2007–2008 financial crisis, together with rises in fuel prices and stringent pollution regulation, led to the need to update the methods concerning ship propulsion system design. In this article, a set of artificial neural networks was used to update the design equations to estimate the engine power and fuel consumption of modern tankers, bulk carriers, and container ships. Deadweight or TEU capacity and ship speed were used as the inputs for the ANNs. This study shows that even a linear ANN with two neurons in the input and output layers, with purelin activation functions, offers an accurate estimation of ship propulsion parameters. The proposed linear ANNs have simple mathematical structures and are straightforward to apply. The ANNs presented in the article were developed based on the data of the most recent ships built from 2015 to present, and could have a practical application at the preliminary design stage, in transportation or air pollution studies for modern commercial cargo ships. The presented equations mirror trends found in the literature and offer much greater accuracy for the features of new-built ships. The article shows how to estimate CO2 emissions for a bulk carrier, tanker, and container carrier utilizing the proposed ANNs.