General Cargo Ships Research Articles

Investigation of VOC emissions from indoor and outdoor painting processes in shipyards

Volatile organic compounds (VOCs) from painting solvents are one of the most important sources of pollutant outputs for the shipbuilding and ship repair industry. Two ships of equal tonnage with the same painted area as each other, which were built in Turkish shipyards, are compared in terms of VOCs produced during painting and coating. Total area of all painted surfaces and total paint consumption of a 3500 deadweight tonne (DWT) oil/chemical tanker and a general cargo ship are calculated. An improved model for calculating the surface emissions of VOCs from painting and coating processes is utilized. Material balance emission estimation approach is employed to calculate the amount of VOCs, since it is used most often where a relatively large amount of material is emitted during use, and/or all air emissions are uncaptured. For both ships calculated VOCs are presented in figures. For the years 2005 and 2006 the total deadweight tonnage of ships delivered in Tuzla region, where 42 shipyards are located, is known. Therefore, a linear estimation is made to guess the total annual VOC emissions caused by painting operations. Finally, this information is used to project the total amount of VOCs emitted to the atmosphere for the year 2010.

大規模地震時の津波避泊図に関する基礎研究

The Tonankai and Nankai earthquake is said to occur 80-90% of the probability in 50 years. Height of tsunami by the earthquake is predicted more than 1.5m in the Port of Osaka. If many ships evacuate at once, they will be in panic in Osaka Bay. Here the Hazard Chart of Tsunami in Osaka bay is proposed for vessel evacuation in safety. Mutual vessels' distances and distance to shore line are estimated around 2,000m. According to statistical data about 110 vessels exist in Osaka Bay a day, the surface area of Osaka Bay has enough to evacuate all of those vessels. Some ban areas and the emergency tracks are designed in the Hazard Evacuation Chart for the dangerous cargo and the large commercial ships, and the Chart is designed for the general cargo ships and the small boats, respectively.

A case study for the effect of a flow improvement device (a partial wake equalizing duct) on ship powering characteristics

A case study for the energy saving in the powering characteristics of a river going general cargo ship has been carried out. Two different hull forms were generated from the original hull form of the vessel to optimise the stern flow of the vessel. A possible energy saving concept, such as partial wake equalizing duct was investigated in this manner. Resistance, self-propulsion and flow visualization measurements were performed with the hull models to explore the effect of partial wake equalizing ducts on the powering characteristics of the hull form. Analysis of the results indicates that the partial wake equalizing duct concept with an appropriate stern design affect not only the flow characteristics at aft-end, but also the propulsion characteristics. In order to identify effect of each component (partial wake equalizing duct and stern form) a further investigation is needed.

Substantiation of a lower estimate for the bunker inventory: Comment on “Updated emissions from ocean shipping” by James J. Corbett and Horst W. Koehler

Substantiation of a lower estimate for the bunker inventory: Comment on “Updated emissions from ocean shipping” by James J. Corbett and Horst W. Koehler

English

English

Automatic collision avoidance system using the concept of blocking area

The authors propose an algorithm for automatic collision avoidance system for ships. The automatic collision avoidance system is one of important functions comprised in automatic navigation system. The concept of inherent blocking area is introduced as a parameter to evaluate collision risk among ships. Contents of blocking areas is defined with the parameters of ship length, breadth, relative speed and relative angle between courses. Numerical simulations using proposed algorithm were carried out with three types of ship such as container ship, VLCC and general cargo ship which have different principal particulars. Results of the simulation show that the proposed system works well for head-on, crossing and overtaking conditions for combination of these ships

大阪湾航行船舶からの大気汚染物質排出量とその削減方策

The atmosphere over the Osaka bay area has been polluted severely for so many years that effective countermeasures against the air pollution have been requested as soon as possible. The discharge amount of NOx, SOx and CO2 from the ships in Osaka bay are estimated in order to know how largely the marine traffic contribute to those air pollutants discharge over the Osaka bay area. The estimation results show that, (1) the ships discharge the about 40% of NOx and SOx of total amount over the Osaka bay area, though the CO2 discharge is very small as 3%, (2) the spatial distributes intensively in the port zones and in the deep east-north region of Osaka bay mainly due to the discharge from tankers and general cargo ships staying there. The IMO/MEPC regulation, which is intending to control the air pollutants discharge of the engines installed on new ships since the year of 2000, cannot be expected so effective for the improvement of severely polluted region such as Osaka bay area. Other countermeasures such as the control of ship speed, cargo handling time, therefore, investigated here and suggests that systematic strategy could be effective when those measures are introduced together, with IMO regulation.

Statistics of ship plating distortions

The paper contains the results of many years of measurements of post-welding distortions of ship hull shell plating. Altogether 1998 plates of general cargo ships, multi-purpose tugs, bulk carriers, chemical carriers, tankers, research vessels as well as passenger/cargo ferries were examined. The deadweight of the ships investigated was within the range of 1300 and 33 350 tons. Results of statistical and regression analyses of the measurements are presented together with a brief description of the measurement technique.

On the manoeuvring performance of a ship with theparameter of loading condition

When predicting ship manoeuvring performance at the initial design stage, it is considered that the loading condition is one of the important parameters for manoeuvring characteristics. To accurately predict ship manoeuvrability, hydrodynamic forces acting on a ship in any loading condition must be estimated. In this paper, approximate formulae for estimating the hydrodynamic forces acting on ships in any loading conditions such as half loaded, ballast and trim by stern conditions are proposed. These approximate formulae were derived from the results of a model test. Thirteen models were used to obtain the hydrodynamic forces consisting of general cargo, car carrier and RORO ships. The model test was carried out on 13 ships for fully loaded condition, on 11 ships for ballast condition and 5 ships for half loaded condition. The predicted results agreed well with the model test results. Therefore, this method will be useful for practical prediction of manoeuvrability for conventional ships at the initial design stage. However since the approximate formulae were investigated on ship models there still remain some problems to be solved such as a correlation, scale effect and so on, to predict the manoeuvring performance of a full scale ship.

海底形状の変化が船の運動に及ぼす効果について

There are not so small number of papers which dealt the item of inclined bottom effect to a moving ship. One of the most famous and epochmaking papers is written by R.W.L. Gawn in 1950. Including this Gawn's research, almost all of the papers dealt a homogeneous bottom; in other words inclined bottom continuing far away from behind the ship to forward. My paper handles the problem of partially existing inclined bottom, that is, a ship sails above a flat bottom, then suddenly she senses an inclined bottom effect, and after about two ship lengths' run, she resumes to above the flat bottom again. I aimed to get qualitative data through having model ships run inertially in a tank in which small portion of an inclined bottom had been put on a flat bottom. Two model ships of a general cargo ship and a tanker of on bulb, had a fixed rudder and no screw propeller. Model ships were pushed ahead using a catapult and after that they run completely free without any actual handling. Notwithstanding the total absence of actual handling, the characteristics obtained through several repeated experiments under the same condition were almost identical. The summarization is as follows; (1) the influence of a partially existing inclined bottom to a moving ship above it is basically the same with those of a homogeneous one, (2) the influence becomes more remarkable as the incline of the bottom increases, (3) the influence depends on the depth-draft ratio and the smaller the ratio, the greater the influence and, (4) the model ships turn the head to sail toward the deeper side, consequently the tracks curve to the deep.

The comparison of general cargo ship economic performance by simulation

Cargo ship designs offered by shipbuilders differ in characteristics such as deadweight, speed, fuel consumption and cargo equipment. The best vessel for high freight markets and high fuel prices may not be the best for low freight markets and low fuel prices. A model has been developed to compare by simulation a number of multi-purpose general cargo vessels suitable for the trade of a Turkish shipowner. The model simulates the operation of each vessel under a variety of operating scenarios, e.g. fuel prices and freight profiles over the ships' lives, and estimates the distribution of resulting net present values. The techno-economic simulation model incorporates variables including ship size, speed, first cost, fuel consumption, load factor and port days. Results are presented for six standard vessels of around 20 000 dwt operating over a long and a short route. Although the ranking of the six varies with assumptions, one design is shown to be superior under most operating conditions.

Influence of Shipform Characteristics on Speed Loss in Wind and Waves

This paper describes the influence of shipform characteristics on resistance increase and speed loss in wind and waves. Resistance increase and speed loss are estimated by calculation. The estimations are carried out for 4 kinds of ships, which are general cargo ships, bulk carriers, pure car carriers and container ships. The particulars of these ships are standardized by auther's former research based on the data of many actual ships.The relations between ship's dimensions and enlargement of resistance increase on each kind of ships are analyzed. And the estimated results of resistance increase of the standardized ships are showed in the form of residual resistance.Furthermore, ship's performance and required power in still water of these standardized ships are supposed by using the latest data of actual ships. Speed loss in wind and waves is predicted by using those performance data. And finally the relations between ship's dimensions and speed loss on each kind of ships are analyzed.The result of these analyses shows that huge ships with low service speed have a trend of causing a great deal of speed loss in wind and waves.

Basic cost–size relations in general cargo ships

This paper discusses a basic cost relationship applied to the purchase costs of general cargo ships, sold in yen, in the period 1975–1984, and delivered by Japanese yards. The use of Fairplay's sample allows classical double log relatonships to be amended for gear, of which only derricks and cranes are considered. As far as the basic cost–size relationship is concerned, a power factor of 0.7 has been estimated. This exactly averages the 0.6–0.8 range,which follows from traditional geometrical properties in mechanical engineering. The specific introduction of ‘number of gear’ by type derricks, cranes or both, allows a single cost function to be identified for all classes with separately estimated cost components for cargo handling gear. The latter prove cranes to be more expensive both in terms of their net installation costs and with respect to their influence on the over-all purchase cost, i.e hull and machinery.

A Calculator-Based Preliminary Ship Design Procedure

The use of computers in naval architecture has increased greatly over the past few years and their usefulness is now being more fully exploited. However, some small firms and individual naval architects do not have access to a computer, due to the high cost, and until recently have had to use more traditional methods. The developments in hand-held, programmable calculators mean that these machines can now execute quite complex programs and yet are within the financial range of the individual. In this paper, a ship design procedure is introduced which utilizes the capabilities of the Texas Instruments TI-59 calculator and PC-100 printer, but is general enough to be implemented on other calculators and computers. The procedure was developed to aid the designer in selecting the principal dimensions for a new design. Thus for a quite small investment the naval architect has gained many of the advantages of the computer, and the programs provide a powerful tool in design work. The procedure has been developed for use with generalcargo ships and bulk carriers, numerically the most common types of ship, but could easily be extended to other ship types, such as oil tankers, cargo liners, and containerships.

Full-Scale Comparative Experimental Study on Propeller Excited Vibratory Forces and Hull Vibrations Induced by a Highly Skewed Propeller and a Conventional Propeller

This paper presents and discusses the results of a full-scale comparative experimental study of two different types of propeller, i.e. a conventional propeller and a highly skewed propeller fitted to a general cargo ship one after the other. Analysis of the measured data indicates that the skewed propeller is effective in reducing afterbody pressure fluctuations and afterbody vibrations. In particular, the amplitude of the pressure fluctuations caused by the 4th order component of shaft revolutions is reduced by about 30 - 40% irrespective of generation of unsteady cavitation or draught condition.

コンテナ船, Ro/Ro船の輸送性能分析

Container- and Ro/Ro-vessels are featured especially by the reduction of terminal time as a result of containerized cargo handling of lift-on/lift-off and roll-on/roll-off method, respectively. This paper analyzes the transportation energy efficiency of both vessels built in Japan so far, with paying attention to the feature mentioned above. Firstly the hull resistance characteristics are analyzed. In the same as car ferry, both vessels have the property being able to separate the hull function into buoyant support and cargo vessel. This property permits the hull form to have less resistance than general cargo ships. The performance level of hull resistance is same for all container-and Ro/Ro-vessels except the large, high speed container vessels with the speed above 26 knots and the displacement above 50, 000 tons, of which hull form are different because of the Panamax limit, and result in inferior level by about 30%. It is pointed out, therefore, that the enlargement of hull size over the Panamax limit is excessive as for the container ship. Secondly the cargo performance, which is indicated by the payload-to-displacement ratio, is analyzed. The payload of container- and Ro/Ro-vessels can be regarded as the carrying number of containers. The above ratio of container vessel is mainly determined by two factors of deadweight-to-displacement ratio and container number on deck loading. The deadweight-to-displacement ratio raises undesirably with speed. While it cannot be improved by the increase of displacement. Therefore the high speed container ship above 26 knots cannot have necessarily good cargo performance in spite of the design for increase of container number on deck loading. The cargo performance of the Ro/Ro ship is worse by two times than the container ship due to the roll-on/roll-off cargo handling method. This demerit sets off inevitably the merit that the Ro/Ro ship can handle cargoes without the special equipment ashore.

U.S. merchant ship noise: Recent measurements and proposed criteria

To provide guidance in the regulation of noise on U.S. merchant ships, noise levels and octave‐band spectra were measured on seven ships of the U.S. Merchant Fleet. Ships selected included tankers, ore carriers, general cargo, and container ships; with steam turbine, gas turbine, and diesel propulsion. They ranged in size from 8000 to 36 000 gross tons and in construction date from the 1920's and 1970's. Locations measured included machinery and engine rooms, passageways, berthing spaces, mess and recreation spaces, bridge, radio room, and offices. Noise exposures based on measured sound levels and time spent in various spaces were calculated for individual crew members in various occupational categories. Exposures are compared with various criteria for hearing conservation, including the 24‐h equivalent continuous sound level (Leq 24). A‐weighted sound levels in other ship spaces are compared with various function‐based criteria, such as speech communication, hearing of warning signals, rest and relaxation, and recovery from temporary hearing loss. Recommended criteria for A‐weighted sound level on U.S. Merchant vessels are presented for immediate use and future goals.

Economies of Scale of General Cargo Ships

ECONOMIES of ship size have in recent years been held up as the salient feature in modern shipping. The size of ships has been increasing very rapidly, leading many students of shipping to believe that no limit exists for the optimal size and that there are only exogenous constraints, such as restricted port depths, etc. This paper presents a model of production and costs of the ship and empirical estimates of both economies and diseconomies to ship size. The approach taken in specifying production and cost relationships is the engineering approach, which seems particularly suitable because of certain basic technological (geometric, in fact) principles. The values of the parameters derived through these technological relationships are confirmed by an empirical estimate of data on production and costs. Unlike industrial plants where plant size is indicative of output capacity, for ships a distinction must be made between two output capacities-the handling capacity and the hauling capacity. Our main conclusion is that while there are economies of ship size in the hauling operations, there are diseconomies to size in the handling operation. The latter factor is the main check on ship size and explains the existence of a wide range of ship sizes currently in service.

MERCHANT SHIPS FOR WARTIME MOBILIZATION PROTOTYPE DESIGN AND CONSTRUCTION FOR READINESS

ABSTRACTThis paper describes the need for modem austere mobilization ship designs carried through prototype construction and operational stages. Such ships would need to be produced quickly during a wartime mobilization effort. Some historical background is presented along with an outline of general ship design requirements. A Maritime Administration conceptual study of three general cargo ship designs is used to illustrate the type of ships, features, and design choices involved. Producibility is the principal requirement with every effort made to decrease lead times and increase production rates. Working plans, needed to make significant reductions in production lead time, and the construction and operation of a prototype are considered necessary for wartime readiness. Alteration of certain design features could make the designs attractive for normal commercial construction and operation although a government sponsored ship building program similar to that for the MARINER design may be most desirable.

Recent Coast Guard Research into Vessel Stability

The paper outlines the development of intact stability criteria for U. S. merchant vessels. Present stability criteria for passenger ships, general cargo ships, tugboats, etc. as well as stability criteria recommended by the Intergovernmental Maritime Consultative Organization are discussed. The paper describes the research into intact stability phenomena that is being sponsored by the U. S. Coast Guard. Results and the scope of the programs at the University of California at Berkeley to investigate ship stability in a seaway and Hydronautics, Inc. to investigate tugboat and fishing vessel stability and the applicability of present criteria are presented. The last section of the paper describes a computer simulation program developed by one of the authors to predict capsizing in following seas.