The Energy Efficiency Design Index (EEDI), introduced by the IMO [1] is applicable for various types of new-built ships since January 2013. Despite the release of an interim guideline [2], concerns regarding the sufficiency of propulsion power and steering devices to maintain manoeuvrability of ships in adverse conditions were raised. This was the motivation for the EU research project SHOPERA (Energy Efficient Safe SHip OPERAtion, 2013–2016 [3–6]). The aim of the project is the development of suitable methods, tools and guidelines to effectively address these concerns and to enable safe and green shipping. Within the framework of SHOPERA, a comprehensive test program consisting of more than 1,300 different model tests for three ship hulls of different geometry and hydrodynamic characteristics has been conducted by four of the leading European maritime experimental research institutes: MARINTEK, CEHIPAR, Flanders Hydraulics Research and Technische Universität Berlin. The hull types encompass two public domain designs, namely the KVLCC2 tanker (KRISO VLCC, developed by KRISO) and the DTC container ship (Duisburg Test Case, developed by Universität Duisburg-Essen) as well as a RoPax ferry design, which is a proprietary hull design of a member of the SHOPERA consortium. The tests have been distributed among the four research institutes to benefit from the unique possibilities of each facility and to gain added value by establishing data sets for the same hull model and test type at different under keel clearances (ukc). This publication presents the scope of the SHOPERA model test program for the two public domain hull models — the KVLCC2 and the DTC. The main particulars and loading conditions for the two vessels as well as the experimental setup is provided to support the interpretation of the examples of experimental data that are discussed. The focus lies on added resistance at moderate speed and drift force tests in high and steep regular head, following and oblique waves. These climates have been selected to check the applicability of numerical models in adverse wave conditions and to cover possible non-linear effects. The obtained test results with the KVLCC2 model in deep water at CEHIPAR are discussed and compared against the results obtained in shallow water at Flanders Hydraulics Research. The DTC model has been tested at MARINTEK in deep water and at Technische Universität Berlin and Flanders Hydraulics Research in intermediate/shallow water in different set-ups. Added resistance and drift force measurements from these facilities are discussed and compared. Examples of experimental data is also presented for manoeuvring in waves. At MARINTEK, turning circle and zig-zag tests have been performed with the DTC in regular waves. Parameters of variation are the initial heading, the wave period and height.
Erdgas fristet ein Schattendasein als Kraftstoff für Verbrennungsmotoren im Allgemeinen und speziell auch für den Antrieb von PKW. Im Jahr 2014 waren 0.7 % aller PKW-Neuzulassungen in der EU Erdgasfahrzeuge [1]. Dennoch bietet Erdgas als Kraftstoff eindeutig Vorteile, vor allem in Hinblick auf die strengen CO2-Richtlinien der EU, die einen Flottenverbrauch von 95 gCO2/km im Jahr 2020 vorschreiben [2]. Erdgas besteht je nach Qualität zu 84 % bis 97 % aus Methan (CH4) [3]. Das H-C Verhältnis von Methan liegt bei 4, während Diesel und Benzin aufgrund der langen Kohlenwasserstoffketten ein H-C Verhältnis von ca. 1.87 aufweisen [4]. Im Grenzfall von 100 % Methan und unter der Annahme gleicher effektiver Wirkungsgrade kann dadurch mit Erdgas der CO2-Austoß im Vergleich zu diesel- und benzinbetriebenen Motoren um 25 % reduziert werden. Zusätzlich weist Methan eine höhere Klopffestigkeit als Benzin auf. Dadurch kann der Wirkungsgrad bei erdgasbetriebenen Ottomotoren gesteigert werden.
The article reviews the evolution of oil skimming systems developed and optimized at TU Berlin in the past three decades. The focus lies on the latest concept – the Seastate-independent Oil Skimming System (SOS), and the associated numerical and experimental studies. The oil skimmer is based on purely hydromechanic principles. It is very robust since it has no moving parts. Investigations with the optimized SOS configuration reveal an efficiency up to 90% in calm waters and up to 65% in the chosen sea states.
A research vessel (RV) plays an important role in many fields such as oceanography, fisheries and polar research, hydrographic surveys, and oil exploration. It also has a unique function in maritime research and developments. Full-scale sea trials that require vessels, are usually extremely expensive; however, research vessels are more available than other types of ship. This paper presents the results of a time-domain simulation model of R/V Gunnerus, the research vessel of the Norwegian University of Science and Technology (NTNU), using MARINTEK’s vessel simulator (VeSim). VeSim is a time-domain simulator which solves dynamic equations of vessel motions and takes care of seakeeping and manoeuvring problems simultaneously. In addition to a set of captive and PMM tests on a scale model of Gunnerus, full-scale sea trials are carried out in both calm and harsh weather and the proposed simulation model is validated against sea trial data.
This paper reports a way of dynamically controlling the sail of a sailboat to reduce the heel angle and roll motion caused by the wind. This is mainly to increase robustness and safety for autonomous sailboats but could also be used to increase comfort for crew. The solution consists of a linear quadratic regulator (LQR) controlling the moment created by the sail. A lookup table will then choose the optimal angle of the sail, optimized for maximum forward acceleration, given the relative wind direction and desired moment. Simulation results are presented to show the effectiveness of the approach.
The 2002 IMO regulations regarding the turning, course keeping and stopping ability for vessels with a length greater than 100 m do not cover the presence of waves, wind and current. But their effects may significantly reduce the manoeuvring performance of ships, especially of smaller vessel types in shallow and restricted waters. Since January 2013, an additional IMO regulation is in force, covering the energy efficiency of ships by defining an Energy Efficiency Design Index (EEDI) that must not exceed a specified reference line for any new-built or converted vessel. The reference line to be met will successively be lowered in three steps. One way to meet the EEDI is a reduction of the installed power, which reduces the powering margin and may lead to significant safety issues for some ship types like smaller general cargo vessels since manoeuvring capabilities in adverse conditions might not be sufficient anymore. Due to the unpredictability of waves, a performance assessment is certainly not feasible in full scale and systematic model test series are time consuming and expensive. It is therefore of utmost importance to develop reliable and efficient software tools that are capable to simulate and predict the seakeeping and manoeuvring behaviour of a vessel at the design stage. In this paper, MARINTEK’s combined seakeeping/manoeuvring simulator VeSim is presented, calibrated and successfully validated by model tests with a general cargo vessel. In this software, the vessel hydrodynamics are solved taking care of both the seakeeping and maneuvering problems simultaneously. External forces result from waves, current and wind as well as from e.g. the propulsion system and mooring lines. The pre-calculated hydrodynamic properties of the vessel include speed-dependent resistance, maneuvering forces (mainly viscous), mass and restoring properties, damping and added mass properties (represented as retardation functions) and viscous roll damping. The maneuvering forces are calculated using current and wave particle velocities as input in addition to the ships velocities. A simulation study with VeSim is performed to find the minimum required power for advancing in head seas as a function of wave period and wave height for a general cargo vessel. In addition, two IMO standard manoeuvres — turning circles and 10°/10° zig-zag tests — are simulated in calm water as well as one regular wave condition in order to exemplify the capabilities of VeSim.
The current demand in liquefied natural gas (LNG) from remote marine locations drives the design of floating LNG (FLNG) liquefaction or regasification facilities, where LNG is transferred to shuttle carriers (LNGC). During the loading procedure, which takes about 18–24 hours for a standard sized LNGC, free fluid surfaces and varying filling levels occur inside the internal cargo tanks. This condition is critical since the seakeeping behavior of the LNGC — especially the roll motion — is strongly influenced and varying. In order to estimate and forecast the LNGC motions, numerical methods based on potential theory are the most efficient and appropriate method. The selected approach is validated by model tests at 30% water filling height inside four prismatic tanks. In-depth analyses, including force and moment measurements between tanks and hull, revealed a discrepancy between the analytical natural modes of a prismatic tank and the resonance frequencies for four prismatic tanks mounted to a LNGC hull. This effect is caused by the ratio of rigid to added mass of the system as well as the fact that the tanks are mounted to a standard hull shape featuring a longitudinal bow-stern asymmetry. In order to investigate this phenomenon systematically, surface elevations inside the tanks and natural modes for a symmetric cuboid hull are compared to results for a standard LNGC hull, both with the same main dimensions. The influence of the tank positions is also considered by comparing the original (longitudinally asymmetric) LNGC tank positions on the cuboid hull to an exactly symmetric arrangement.
