Ship Berthing Research Articles

Minimum time-energy trajectory planning for automatic ship berthing

A ship optimal trajectory planning method based on the dynamic model of the ship is presented. First a mathematical modular model is introduced for describing the non-linear dynamics of the ship. Then the problem of optimal trajectory planning is discussed. The trajectory is obtained through the optimization of a time-energy criterion, taking into account constraints on the steering system, environment, non-linearities, and non-convexity of the state space equations. The discrete augmented Lagrangian approach is used to compute the optimal constrained controller. The method was programmed on a HP700 workstation. This approach was applied to automatic ship berthing maneuver. >

International Trade in Natural Gas

World reserves of natural gas and oil, converted into energy terms, are about equal. Natural gas supplies approximately one-fifth of the world's energy consumption; oil two-fifths; the remainder comes from various other sources, such as nuclear power, coal, and hydroelectric power. The imbalance between natural gas and oil results from the incongruent geography of reserves and consumption. Economic factors include the economics of transportation, which is related to geography. Market factors, such as amount of consumption and substitutability, must also be considered. These factors are all highly dynamic. Between 1975 and 1992 natural-gas consumption worldwide rose 67 percent, in contrast with 17 percent for oil. Most significant of the changes was the growth in industrial consumption of natural gas, which is geographically concentrated in the developed part of the world. All of these phenomena interact through pricing mechanisms that include market arrangements such as contracts and governmental policies and activities. This article focuses on the international trade in natural gas, although observations can also apply to limited national and subnational contexts. In 1992 international trade accounted for only 16 percent of the world consumption of natural gas. Three-quarters of the gas moved by pipeline and the remainder, as liquefied natural gas. This proportion can also change. For example, pipeline exports from the former Soviet Union dropped substantially in recent years, but that decline was offset by increased exports by pipeline from Canada to the United States. Long-term international trade in liquefied natural gas can be expected to increase and that by pipeline, to decrease. Costs of natural-gas production differ with geological conditions, depth and size of production zones, yields per well, type of terrain, and transportation. Natural gas has no significant refining costs, except to handle the noxious substances released into the air. There is also no costing problem for associated gas from oil production. Much of this associated gas is burned off or reinjected into wells to raise pressure. The problem of costing natural gas is becoming more complicated as deeper drilling is now required, especially in long-established producing regions such as North America. Because of pipeline transportation, costs for entry equivalents and distance are significantly higher for natural gas than for oil. To start with, pressure in pipeline technology is greater for natural gas than for oil: the same diameter pipeline can carry one-fifth of the energy of the former than of the latter a day, even though the former flows much faster. These higher transportation costs tend to restrict natural gas to regions close to production. For example, in Great Britain the cost of transporting natural gas to consumers is higher than the cost of the gas. To minimize costs the British government has a privatized company with a monopoly on supplying households, which permits maximum utilization of transportation facilities and reduces overall costs. Because of flammability and dangers of explosion, much governmental regulatory intervention in pipeline transportation has been imposed and tends to increase with time and experience. Regulations lead to control of quantities of natural gas that can be transported, which affects markets and price interference and control. Imposition of such controls occurs even where governments traditionally intervene little with markets and the economy. Risk of flammability and explosion is even greater for ship transportation than for pipelines. The natural gas is liquefied and cooled in an expensive process. The large facilities occupy much land and must provide ship berthing that minimizes the loss of coldness. Tankers carrying the liquefied gas must be large, at least 250,000 tons deadweight, to be economical. At destination terminals the liquefied gas is returned to its former state and then distributed to consumers. …

Optimizing ship berthing

Abstract : Ship berthing plans reserve a location for inbound U.S. Navy surface vessels prior to their port entrance, or reassign ships once in port to allow them to complete, in a timely manner, reprovisioning, repair, maintenance, training, and certification tests prior to redeploying for future operational commitments. Each ship requires different services when in port, such as shore power, crane, ordnance, and fuel. Unfortunately, not all services are offered at all piers, and berth shifting is disruptive and expensive: A port operations scheduler strives to reduce unnecessary berth shifts. We present an optimization model for berth planning and demonstrate it for Norfolk Naval Station, which exhibits all the richness of berthing problem:. the Navy faces.

Modeling for Ship Design and Production

The flexible operating and changing of the complex one-of-a-kind shipbuilding environment has to be based on adequate concepts and instruments to handle the related controlling, planning and implementation tasks. Product modeling defines the physical and application driven product-related information. It is of basic importance to support this environment, especially the concurrent engineering functions, during the whole product life cycle. Process modeling supports the implementation and operation of complex CIM (Computer Integrated Manufacturing) oriented processes. In this paper some modeling applications within European shipbuilding research and development projects will be highlighted from the viewpoint of an integrated product and process modeling approach. The following projects referenced: NEUTRABAS (Neutral Database for Complex Multifunctional Systems) explores a broad application field of product information for ship steel structure and outfitting systems; ROCOCO (Real Time Monitoring and Control of Construction Site Manufacturing) develops a CIM application and demonstrates this application within the pipe outfitting environment of a ship berth construction site; and MARIN-ABC (Marine Industry Applications of Broadband Communication) demonstrates new applications and services in the maritime transportation business based on future mobile satellite networks.

Residual Deformation and Cumulative Fatigue Damage Ratio of Breasting Dolphin by Single Pile Structures

Currently, breasting dolphins of deepwater terminals are designed so as ship's berthingenergy shall be absorbed mainly by fenders. As for a singel pile structure (SPS) whichconsists of high-tensile steel, ship's berthing energy shall be absorbed mainly by piles.Major subjects to be cleared for design ofSPS are the lateral load-deflection characteristicsof piles against large deformation, estimatation of residual deformation underrepeated loads and evaluation the safety for fatigue. In this report, both residual deformationand cumulative fatigue damage ratio within a lifetime are computed with considerationof ship's berthing and mooring forces. The lateral load-deflection characteristicsof SPS against large lateral repeated loads which are obtained from the field tests andmodel experiments are taken into consideration in this study.

AN ADJUSTABLE MARINE FENDER SYSTEM PROGRAMMED WITH THE AID OF NUMERICAL MODELS IN ORDER TO MINIMIZE BERTHING AND MOORING LOADS

An adjustable marine fender system, programmed with the aid of mathematical models, can substantially contribute to safer berthing and mooring of ships with various water displacements, operating at high or at low speed under varying wind, wave and current conditions. This doesn't only imply a reduction of risks to vessel and terminal structures but also in case of exposed sites or of unruly waters, a - possible substantial - reduction of ship's costly down-time.

New Mooring System to Reduce Ship Motions and Berthing Energy

ABSTRACTIn this paper, the improvement of mooring system in a harbor often attacked by storm waves is discussed by numerical simulation. First of all, it is pointed out that the ordinary mooring system which consists of fenders and mooring lines is not suitable for a ship moored to a quay from the viewpoint of ship motions and mooring forces. We also find that the damping function of dash-pots equipped in the mooring system is effective to reduce ship motions and berthing energy. Then, we propose the optimum mooring system attained by diminishing the spring constant of fenders and by providing dash-pots in fenders.

Erratum for “The Berthing of a Ship to a Jetty”

Erratum for “The Berthing of a Ship to a Jetty”

The Berthing of a Ship to a Jetty

A mathematical model has been developed that describes the behavior of a ship berthing to a jetty (or similar facility) and predicts the fender loads. Use is made of the so-called impulse response function technique that has as the restriction that the ship-fluid system is supposed to be linear and time invariant. This approach enables the inclusion of external forces of arbitrary nature. Maintaining all essential features it produces results of sufficient accuracy for practical applications. The mathematical model is applied to the case of a schematized ship that, on calm shallow water with relatively large horizontal dimensions, berthes—at zero forward speed—to an open jetty-type berthing structure equipped with one undamped (non-) linear fender without mass of its own. For verification experiments were carried out on a (small) scale model. The calculated results show a good agreement with values obtained from the experiments.

Container ship turnaround times at UK ports

This paper looks at the relationships between ship size, handling rate and ship berth time for five major ports in the United Kingdom. The results show that there is no simple linear relationship between these variables. The causes and implications of this are discussed.

Rational Design Concept for Breasting Dolphins

New deepwater ports are often designed with small operating platforms incapable of withstanding the impact of a berthing ship. These platforms are protected by breasting dolphins. Based on past studies, it is concluded that the designer may assume that one-half of the ship's kinetic energy, as calculated for a berthing velocity of 0.5 fps, will be the maximum energy to be absorbed by a single dolphin at facilities which service large vessels. It is proposed that freestanding tubular piles be used as breasting dolphins at such facilities. A scheme for accomplishing the analysis of such dolphins is presented which leads to an accurate assessment of the energy absorption characteristics of the dolphin. The paper concludes with a case study which demonstrates the analytical scheme, pointing out in particular that the computed response of a dolphin to impact is nonlinear.

CATHODIC PROTECTION.

A short history of cathodic protection, from the discovery of its operating principle about 1800 and its use by Sir Humphry Davy a few years later, is followed by a description of where and how corrosion of metal occurs, the use of wrapping and of a sand bed around a pipeline, cathodic protection of pipelines, and of steel-piled jetties, appropriate levels of impressed current, and the prevention of sparking between a berthing ship and a cathodically protected petroleum jetty. Periodic verification of the effectiveness of both impressed-current and sacrificial-anode systems of cathodic protection is necessary, and worn-out anodes have to be replaced. The Author describes the half-cells of copper/ copper sulphate and silver/silver chloride which are used for testing protection systems in soil and sea water respectively, and states appropriate voltage levels for each. The Paper also describes a typical cathodic protection installation with impressed current.

The Analysis of Ship Structures Subjected to Slamming Loads

This paper describes the results of a fundamental study of various phases of the ship structural design problem, as affected by slamming-type loads. By a slamming load, we mean a suddenly applied impact-type load such as is introduced for example, by: (a) The pitching and heaving motions induced by waves, which in turn cause the ship's bow to emerge and then reenter the seaway at a relatively high velocity. Upon reentering the sea, suddenly applied impact-type loads may be applied to the ship hull. These cause a sudden change in acceleration, generally felt as a shudder (or series of shudders or vibrations) which introduces the slam loading. (b) Berthing or docking of ships. If, for any reason the berthing introduces heavy impact loads due to sudden contact between the ship hull and the fender-dock system then we have a response very similar to that described in (a). The study[1]2 was concerned with several different facets of the over-all slam problem. Among the topics considered (and reported upon herein) are 1) time effect in ship-slamming problems; 2) damping of slam oscillations; 3) model scaling requirements for slam phenomena; 4) an approximate method of analysis for ship hulls (in the elastic range) subjected to slam loads; 5) comparisons between the method 4) and other methods; 6) extension of 4) to the elastoplastic range.

A review of radio aids to aeronautical and marine navigation

The paper is an introduction to the Convention on Radio Aids to Aeronautical and Marine Navigation.The parts of the radio-frequency spectrum which are in use for navigational purposes extend from about 10kc/s to 40Gc/s. The basic factors which apply to all radio-navigational technique are the wave-path, measurement of time interval, the wave propagation velocity, base-line distance and aerial aperture. For short-distance navigation the predominating source of error is usually in the measurement of time interval, but at greater distances it is due to an inexact knowledge of the wave propagation velocity.The navigational requirements of ships and aircraft are similar, but the means of meeting these requirements differ, because ship navigation involves movement in two dimensions and aircraft in three dimensions. For example, this has caused the design of shipborne and airfield radar aerials to differ appreciably. Development of radar in frequency bands above 30Gc/s is continuing in order to obtain systems with greater resolving power, but at these frequencies the high-energy absorption during heavy rain is a handicap to their use.Self-contained aids to navigation such as dead reckoning, Doppler and inertia navigation involve integration processes, the errors being dependent upon the quality of the information used and the integration time. They have a wide field of application over the undeveloped parts of the world, but in areas of high traffic density, their ability to give adequate protection against collision is obscure. In consequence, navigational techniques which define a common co-ordinate system to all users within their coverage are preferred. The V.H.F. Omnmi-Range, Tacan and Dectra systems are mentioned as examples of these techniques.A section deals with precision navigation which applies to the landing of aircraft and the berthing of ships. The suggestion is made that pilot vessels should be fitted with high-precision radar for berthing operations, and v.h.f. television links should be used to assist the pilot of the vessel being berthed.The paper concludes with a look into possible future fields of application and mentions high-stability frequency sources and artificial earth satellites as devices which may be used in the future to assist navigation.

The Design of Piers, Jetties, and Dolphins

This paper deals with the design of piers, jetties, and dolphins with particular reference to the lateral loads from berthing ships which these structures must withstand. Design principles are examined, and two examples of pier design are reviewed: (a) Guayacan Bay Pier, Chile (built for Bethlehem Chile Iron Mines) and (b) Hoboken Pier “C”, Hoboken, N. J. (built for the Port of New York Authority). The paper shows how the impact energy of a berthing ship may be absorbed by the elastic deformation of the structure, without the need for any special system for spring fend ering.