Ship Form Research Articles

Numerical investigation on fast displacement ship hydrodynamics

In last decade, sustained efforts have been made to improve ship energy efficiency, to reduce fuel consumption and carbon dioxide emissions by means of optimizing the hull forms and propulsion system. The aim of the present paper is to search for solutions to improve the fast-displacement hull forms of passenger ships that navigate on the Danube river and the Black Sea coast, leading to high energy efficiency, reduced emissions and minimised shore-side effects. To investigate the flow around a 31 m fast-displacement monohull passenger ship, a series of 5 numerical simulations for a range of speeds between 4.5 and 12.5 m/s were performed in order to estimate the forces acting on the ship, but also to analyse the hydrodynamic parameters of the flow. Based on the first series of calculation, several solutions to improve the hydrodynamic performance of the hull are considered. The two most effective solutions found have been the trim edge and the interceptor. Different configurations and angles have been systematically investigated in order to find the most efficient geometrical parameters. Finally, the hull with trim wedge leads to a reduction of the power consumption by 2.4 to 5.5% and the interceptor by 2.8 to 8.8%, for speeds higher than 8.4 m/s. For speeds lower than 8.4 m/s the power consumption is higher than bare hull. Moreover, the solutions proposed are easy to implement for new built ships, but also for ships in operation.

POLYSEMICITY OF THE TERMS «DEMURRAGE» AND «DETENTION» APPLIED IN THE PRACTICE OF LINER AND TRAMP SHIPPING

Purpose. The presented study aims to systematize the definition of the terms «demurrage» and «detention», which are used in the theory and practice of maritime transportations, but are characterized by different meaningful definition when used in liner and tramp shipping, which requires the need for a comparative analysis. Methodology. For the stated comparative analysis, the applied information sources allowed to determine the specificity of the terms «demurrage» and «detention» both at the scientific level and at the level of practical implementation. Findings. The authors proved that despite their synonymous character, the terms «demurrage» and «detention» have fundamental differences when used in transportation contracts for the vessels of liner and tramp shipping. Taking into account the specific conditions of these organizational forms of shipping, the terms, the meaningful interpretation of which are the object of the study, have a different object of accrual, the procedure for substantiating the value of the corresponding rates and the procedure for calculating the total amount. Originality. The authors for the first time carried out a study in the context of two forms of organization of maritime transport (tramp and linear) and established the semantic features of the marine terms «demurrage» and «detention». Practical value. The commercial practice of transport companies, in particular shipping ones, is closely connected with technical, technological, organizational, legal, economic and even linguistic issues. The last aspect concerns the role of the accuracy of understanding of the terms by the parties to the transportation contracts concluded by shipping companies (liner and tramp shipping) with counterparties, since it is the responsibility of a material nature that follows from them. Clear interpretation of the terms is crucial to prevent possible disputes regarding the relevant payments. Uncertainty, which is currently present in scientific publications and literary sources of practical nature, leads to a free interpretation and substitution of the analyzed terms with each other without a clear distribution of the parties' responsibility in different forms of shipping.

An Evaluation Transport Capacity Structure Adjustment Model on the Effect of Ship Standardization and Ship Dismantling Policy

Firstly, it introduces the background of ship form standardization and ship dismantling policy, and combs the previous research results. This paper establishes the model of ship capacity structure adjustment and the model of policy implementation effect, and then uses the model to analyze the change of ship capacity structure and its implementation effect in the process of policy implementation. Among them, the change of ship's capacity structure is analyzed by stages of ship types, including the change of ship's capacity increment and the change of ship's age structure along the coast. The implementation effect analysis is divided into three aspects: the proportion of old and new ships, the change of average tonnage and the change of average ship age.

European trading, whaling and climate history of West Greenland documented by historical records, drones and marine sediments

The European trading and whaling activities of the 17th– 19th centuries provide records of climate and sea- ice conditions off West Greenland in the form of ships’ logs and other official documents in many archives around Europe. These documents, combined with evidence from marine sediments, help describe climate changes in general, and seaice volume changes in particular, in connection with human activity in the region. The Greenland National Museum & Archives in Nuuk (NKA) hosts a unique collection of original documents presenting detailed insight into weather and ice conditions as well as the daily life of the colonial centres and outposts recorded by the documents of the Danish administration. These documents also reveal many aspects of the interaction between the Inuit and Europeans from 1779 onwards. Information retrieved from the archives in Nuuk has been combined with results from palaeo-environmental investigations of marine sediment cores to unravel climate variability and changes in sea ice. This information has been supplemented with data from an extensive field programme using drones to document onshore remains from the whaling period in the Disko Bugt region (Fig. 1).

The role of the Northern Sea Route in Russian LNG Projects Development

Currently, there has been a significant increase in the volume of freight traffic on the Northern Sea Route (NSR). The following advantages of the Northern Sea Route can be mentioned: no piracy in the region, less time taken for cargo transport, ship bunkering with natural gas from onshore or offshore fields. The paper indicates that the requirements for the bunker fuel quality and the amount of pollutant emissions into the atmosphere during shipping in the Arctic zone are very stringent. This work states that one of the most important ways to follow the emission limits is changing the fuel of the ice-rated vessels for liquefied natural gas (LNG). It is noted that Russia has a number of opportunities to apply LNG both to supply the Arctic Region with water and surface transport and to supply the onshore settlements and enterprises. It is noted that the use of gas as fuel will decrease air pollutant emissions. Furthermore, shift to LNG as bunker fuel will resolve a major environmental problem of accidental spillage of marine fuel and crude oil. The article states that LNG is a reliable and competitive fuel for shipping in the Arctic Region. It is indicated that the growth of the Russian domestic LNG market in the form of industrial consumers and ships bunkering can be an incentive for the intensive domestic LNG-projects development.

A new method for parametric design of hull surface based on energy optimization

A method for parametric design of hull surface based on energy optimization is presented. This method aims to obtaining the fairness hull surface based on NURBS. The traditional design method, based on the offsets to express ship form, does not really reflect the characteristics of the hull surface and is not easy to modify ship form. Hence the energy optimization method is proposed to obtain the expression of the hull curves and surface with NURBS. Attentions are focused on extracting the design parameters which represent the characteristic of the hull. The design parameters are selected as design variables meanwhile least sum of curvature square of hull curves is set as optimization objective. The basic shape feature of hull curves and surface can be adjusted under the constraints related to interpolation points, derivative vectors, curvatures, areas and centroid points. One successful design example of a 50000DWT tanker verifies the feasibility and practicality of this method. This method has a better performance in the design variability and model remodeling without relying on parent data, which realizes further fairness of the ship hull surface.

Regularity of Optimal Ship Forms Based on Michell’s Wave Resistance

We introduce an optimal shaping problem based on Michell’s wave resistance formula in order to find the form of a ship which has an immerged hull with minimal total resistance. The problem is to find a function $$u\in H^1_0(D)$$ , even in the z-variable, and which minimizes the functional $$\begin{aligned} J(u)=\int _D|\nabla u(x,z)|^2dxdz+\int _D\int _Dk(x,z,x',z')u(x,z)u(x',z')dxdzdx'dz' \end{aligned}$$ with an area constraint on the set $$\{(x,z)\in u(x,z)\not =0\}$$ and with the volume constraint $$\int _D u(x,z)dxdz=V$$ ; D is a bounded open subset of $$\mathbb {R}^2$$ , symmetric about the x-axis, and k is Michell’s kernel. We prove that u is locally $$\alpha $$ -Holder continuous on D for all $$0<\alpha <2/5$$ , and locally Lipschitz continuous on $$D^\star =\{(x,z)\in : z\not =0\}$$ . The main assumption is the nonnegativity of u. We also prove that the area constraint is “saturated”. The results are first derived for a general kernel $$k\in L^q(D\times D)$$ with $$q\in (1,+\infty ]$$ . A numerical simulation illustrates the theoretical result.

Study on Green Water of Tumblehome Hull Using Dam-Break Flow and Ranse Models

Abstract The tumblehome hull adopts some novelty designs such as low-tumblehome freeboard and wave-piercing bow. The new form design makes the ship have many special hydrodynamic performances. Especially the green water of tumblehome hull is different from that of hulls with flare free board. Green water is a strong nonlinear phenomenon of ship-wave interaction, the variation of free surface of liquid is complicated, and there are still some difficulties to solve green water problems well with numerical simulation method. In this paper firstly the motion responses of the tumblehome hull was calculated based on 3D potential theory, and then the dam-break flow model was used to calculate green water height and pressure distribution. According to the result of numerical simulation, some typical working conditions are chosen for 3D CFD simulation using RANS method. The results of numerical simulation methods are compared with the experimental results measured in towing tank. The influence of different ship form parameters and wave parameters to the green water of tumblehome hull is analyzed, and some regularities of green water on tumblehome hull in regular waves are summarized.

STUDI HAMBATAN DAN KECEPATAN KAPAL TIPE LAMBUNG SERIES 60 DITINJAU DARI TIGA BENTUK HALUAN KAPAL

Research that has been done resulting hull of Series 60 is one model of ship hulls. Series 60 hull is used for the a merchant ship to block coefficient range from 0.65 - 080. Research Series 60 hull has great success, the American Towing Tank Conference (ATTC) and the International Towing Tank Conference (ITTC) agreed to fund further research for the Series 60 hull. The results of further research, published by the Society of Naval Architects and Marine enginners (SNAME). hull form series 60 is still widely used for type of commercial ships due to have a midship U is almost square so that traffic carried quite a lot of it is important for commercial ships, in addition to stability is also good. The bow of a ship is part of the greatest pressure and voltages, as the brunt of the water and the ship blows waves. Modeled and analyzed Series 60 Hull with a sloping shape of the bow, the bulbows and X-Bow with the main dimension of the vessel : Lpp = 30.97m, B = 4.34m, T = 1.7m. To further analyze the effect of the three forms of the bow ship for resistance and speed. Analyzed to three forms of the hull at speeds of 0 to 8.25 knots have resistance almost flat at around 7000 Newton, meaning the ship relatively similar obstacles. At speeds above the 8.25 knots have resistance vessel with a hull tilted began to increase with increasing vessel speed has become increasingly apparent obstacles ships is increasing drastic, especially at a speed of 30 knots have resistance of ship 257733 Newton when compared with resistance vessel for bulbows form who is resistance 230059 Newton or X-bow have resistance 228943 Newton.

Modeling and simulation of five DOF motions for SWATH ships

To develop marine simulators of Small Waterplane Area Twin Hull (SWATH) ships and gain a better understanding of the maneuverability of the SWATH, a mathematical model with five Degree of Freedom (DOF) for SWATH has been established, in which the surge, sway, yaw, roll and pitch motions are all considered. The characteristics of the SWATH ship form and the hydrodynamic interaction among the twin bodies, twin propellers and twin rudders are taken into consideration on the basis of the three DOF maneuvering mathematical model. To verify the effectiveness of the modeling and ensure the use of the model in marine handling simulators, a detailed model is tentatively established on the basis of empirical formulas. Based on the acquired results, tests were performed to simulate the steady turning and zigzag motions of the ship. The results are in accordance with regular pattern and trend of motion of SWATH ships. This verifies the effectiveness of the mathematical model of the turning movement.

A Novel Restraining System for a Powerless Advancing Ship: A Combined Theoretical and Experimental Investigation

A novel flexible restraining system is proposed to protect a waterway crossing road, a railway, or a combined bridge when a powerless advancing ship approaches such a structure. Direct collision with principal bridge supports is not addressed under the assumption that the restraining system is located some distance upstream of the non-navigational bridge, assuming the ship cannot engage propulsive system in reverse to reduce the speed of ship advance. Ship-independent seabed-located gravity anchors are to be ultimately dragged to dissipate ship kinetic energy. A mathematical model of the proposed method of restraint is developed and the resulting movements of ship and anchors are predicted for two distinct ship forms. These ships' responses are investigated for initial ship velocity, angle of approach, and point of contact with restraining cable of different investigated spans in the presence and absence of a current. The theoretical simulations agree reasonably well with the related model measurements given the existence of ship sway and yaw motions are not addressed. The results are sufficient to demonstrate the applicability of the proposed system. Predictions and observations suggest that the smaller the restraining cable span and the closer the ship is located to the anchors (initially vertically below the ends of the restraining cable), the more effective is the retraining process.

Numerical evaluation of longitudinal motions of Wigley hulls advancing in waves by using Bessho form translating-pulsating source Green’S function

In the framework of 3D potential flow theory, Bessho form translating-pulsating source Green’s function in frequency domain is chosen as the integral kernel in this study and hybrid source-and-dipole distribution model of the boundary element method is applied to directly solve the velocity potential for advancing ship in regular waves. Numerical characteristics of the Green function show that the contribution of local-flow components to velocity potential is concentrated at the nearby source point area and the wave component dominates the magnitude of velocity potential in the far field. Two kinds of mathematical models, with or without local-flow components taken into account, are adopted to numerically calculate the longitudinal motions of Wigley hulls, which demonstrates the applicability of translating-pulsating source Green’s function method for various ship forms. In addition, the mesh analysis of discrete surface is carried out from the perspective of ship-form characteristics. The study shows that the longitudinal motion results by the simplified model are somewhat greater than the experimental data in the resonant zone, and the model can be used as an effective tool to predict ship seakeeping properties. However, translating-pulsating source Green function method is only appropriate for the qualitative analysis of motion response in waves if the ship geometrical shape fails to satisfy the slender-body assumption.

Investigation of springing in ship structures using experimental methods and 3-D hydroelastic theory

Large and long ships experience springing behavior. Depending on the trade routes and design of such ocean-going ships, wave-induced vibrations may be due to springing and whipping effects. In this paper, we address the wave-induced vibrations in an ultra-large ore carrier under fully loaded and ballast conditions. The experimental measurements from tests performed using a flexible model of the ship were compared with the numerical predictions from 3-D hydro-elastic theory (THAFTS) (Wu, Hydroelasticity of floating bodies. PH.D thesis, Brunel University, 1984). The measurements showed multiple frequencies between the encountered wave frequency and the 2-node bending frequency that occurred only in ballast conditions, whereas the springing vibrations were more apparent with forward speed under ballast conditions in both regular and irregular waves. The numerical method predicted the vertical bending moment quite well in the fully loaded condition but underestimated it in the ballast condition. This result was primarily due to an inability to capture the prediction of the multiple frequencies between the encountered wave frequency and the 2-node bending frequency. Using THAFTS, a new ship form with a deep draft was introduced, and this vessel was shown to reduce springing vibrations.

A theoretical and numerical determination of optimal ship forms based on Michell’s wave resistance

We determine the parametric hull of a given volume which minimizes the total water resistance for a given speed of the ship. The total resistance is the sum of Michell’s wave resistance and of the viscous resistance, approximated by assuming a constant viscous drag coefficient. We prove that the optimized hull exists, is unique, symmetric, smooth and that it depends continuously on the speed. Numerical simulations show the efficiency of the approach, and complete the theoretical results.

Threshold free shipping policies for internet shoppers

This study examines how consumers evaluate and respond to two economically equivalent but different forms of threshold free shipping (TFS) policy: piece-based or dollar-based (e.g., Regular: $25; free shipping on orders of “4 items” as opposed to “$100”) offered by an online store. We first demonstrate that a piece-based TFS will result in a higher intention to shop than a dollar-based TFS. However, this effect is attenuated when information about the shipping charge is present (e.g., “$4.99 flat rate shipping. Free shipping on orders of ___”) or when the time restriction for the TFS policy is short (e.g., “today only”). Finally, the effect of the TFS policy on intention to shop is shown to be mediated by the consumer’s evaluation of the offer. The observations have important implications for internet retailers.

Study on Optimized Hull form of Basic Ships Using Optimization Algorithm

In order to achieve minimum resistance for a ship hull, we used an optimization algorithm and computational fluid dynamics to develop a hull-form design. An ITTC 1957 modelship correlation line formula was used to estimate the frictional resistance coefficient, and the wave-making resistance coefficient was evaluated by the Rankine source panel method with nonlinear free-surface boundary conditions. The geometry of the hull surface was represented and modified by a B-spline surface-modeling technique during the optimization process. Wigley and series 60 (C_B=0.60) hulls were selected to obtain an optimized hull that produces minimum resistance. Experimental tests were carried out for the modified series 60 (C_B=0.60) hull.

A STUDY ON OPTIMIZATION OF SHIP HULL FORM BASED ON NEURO-RESPONSE SURFACE METHOD (NRSM)

Building large and eco-friendly ships has become a clear trend in the ship building industry. Research to minimize ship resistance has actively been investigated for energy savings and environmental protection. However, optimization of the full geometry, while taking into account the hydrodynamic performance is difficult because extensive time is needed to calculate the performance factors, such as the resistance and propulsion. Hence we suggest an optimal design framework based on the neuro-response surface method (NRSM) for optimal shape design in consideration of hydrodynamic performance. The optimization algorithm of the constructed framework consists of the back-propagation neural network (BPN) and the non-dominated sorting genetic algorithm-II (NSGA-II). Using the framework, we performed a case study to optimize the hull form of a 4300TEU container ship with consideration of wave resistance, viscous pressure resistance, and wake fraction.

체적 밸런스 선형변환방법에 대한 연구

This paper aims at contributing to the field of ship design by introducing new systematic variation methods for ship hull forms. Hull form design is generally carried out in two stages. The first is the global variation considering the sectional area curve. Because the geometric properties of a sectional area curve have a decisive effect on the global hydrodynamic properties of ships, the design of a sectional area curve that satisfies various global design conditions, e.g., the displacement, longitudinal center of buoyancy, etc., is important in the initial hull form design stage. The second stage involves the local design of section forms. Section forms affect the local hydrodynamic properties, e.g., the local pressure in the fore- and aftbody. This paper deals with a new method for the systematic variation of sectional area curves. The longitudinal volume distribution of a ship depends on the sectional area curve, which can geometrically be controlled using parametric variation and a variation that uses the modification function. Based on these methods, we suggest a more generalized method in connection with the derivation of the lines for a new design compared to those for similar ships. This is the so-called the volumetric balanced variation (VOB) method for ship forms using a B-spline modification function and an optimization technique. In this paper the global geometric properties of hull forms are totally controlled by the form parameters. We describe the new method and some application examples in detail.

Ship Form Optimization of 62-Feet Yacht and Analysis of Performance

This paper focus on the ship form optimization of a 62-feet yacht and uses experienced method based on amount of statistical data to change the width of knuckle lines in order to reduce the resistance of the hull, including comparison of performance of stability and see keeping.

Spatial and temporal variation and air–soil exchange of atmospheric PAHs and PCBs in an industrial region

It was recently suggested that emissions of some persistent organic pollutants (POPs) are decreasing in former use regions due to emission reductions combined with uncontrolled export, at the expense of regions receiving these substances as obsolete products and wastes. Aliaga industrial region in Izmir, Turkey is one of the regions receiving POPs in the form of scrap iron and old ships to be scrapped. Ambient air samples were collected by passive sampling during four seasons in 2009 and 2010 (winter, spring, summer, and fall) at forty different sites in Aliaga to determine the spatial and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Soil samples were also collected at the air sampling sites during the summer period. Phenanthrene was the most abundant PAH at all sites, and all samples were dominated by low to medium molecular weight PAHs, i.e., fluorene, fluoranthene and pyrene. The spatial distribution of ambient PAH concentrations indicated that the major PAH sources in the region were iron–steel plants, petroleum refinery, and ship dismantling plants. At residential sites, PAH concentrations were higher in winter indicating that wintertime concentrations were mainly affected by residential heating emissions. However, highest atmospheric PCBs concentrations were observed in summer, probably due to increased volatilization from their sources at higher temperatures. Low to medium molecular weight PCBs (tri–, tetra–, penta–CBs) were the most abundant compounds in air for all seasons. Results also indicated that iron–steel plants and ship dismantling facilities were the major PCB emitters in the region. A similar spatial variation was observed for soil PAH and PCB concentrations. Air and soil PAH and PCB concentrations were correlated significantly indicating the interaction of these compartments. Results of the fugacity ratio calculations indicated that local soils generally act as a sink throughout the year for medium to low volatility atmospheric PAHs and PCBs. However, during summer soil becomes a source, especially for volatile PAHs and PCBs.