Cable Ship Research Articles

Towing Winch Control System for a New Cable Laying Ship

Towing Winch Control System for a New Cable Laying Ship

Protection of Cable Ships Engaged in Operations for Submarine Telecommunication Cables

ABSTRACTThis article discusses legal mechanisms for the protection of cable ships engaged in operations for submarine telecommunication cables. It argues that all states should legislate to provide that the interference with cable ships engaged in cable operations, done willfully or through culpable negligence, should be a punishable offense.

FUZZY P+ID Controller for a Constant Tension Winch in a Cable Laying System

A constant tension towing winch maintains constant towing rope tension between the cable ship and the cable laying machine. In this paper, an active constant tension controller based upon a hybrid FUZZY P+ID strategy is proposed to improve the performance yield of the conventional PID controller that was implemented on the towing winch. The FUZZY P+ID controller replaces the P item of the conventional PID with the FUZZY P item, but the I and D items remain unchanged. The comparative studies of the FUZZY P+ID and traditional PID controllers were conducted, and the numerical simulation results show that the performance of the proposed FUZZY P+ID controller is superior to that of the PID controller. The proposed FUZZY P+ID controller was implemented in the constant tension towing winch to substitute for the existing PID controller. The real applications for driving the submarine cable laying ship under harsh undersea conditions demonstrated the robustness of the FUZZY P+ID for a number of unmeasurable disturbances, such as the buoyancy, the drag force, and wave effects.

敷設・回収時における海中分岐装置ジンバル曲げ角の検討

The submerged Branching Unit (BU) connects the optical submarine trunk cable and the branched two optical submarine cables by the gimbals joints attached between BU and each cable coupling (CPL). This paper shows the geometrical condition to pass the BU through the bow sheave of the cable ship within the limited bending angle of the gimbals joint. The bending angles of the gimbals joint of the branched two cables are derived by solving the geometrical condition numerically and tell us that the selected size of the bottom width of the sheave will have the suitable size of the CPL boots diameter to keep the bending angle within the limited angle. We accordingly select the size of the bottom width of the sheave and the suitable size of the CPL boots diameter. The tensile test result of the bending angle of the gimbals joint of the BU with the suitable size of the boots diameter installed on the test facility sheave being modified to the selected size of the bottom width demonstrates the validity well of the solution of the geometrical condition. The BU was successfully laid to and recovered from more than 6,000 m deep in the Pacific Ocean with the modified bow sheave and the suitable CPL boots.

Technology in Undersea Cable Systems: 50 Years of Progress

AbstractUndersea cable systems provide a comprehensive example of how technology has changed during the 50-year publication history of the MTS Journal. From the 125-μm‐diameter glass optical fiber to the 12,000-ton cable ships, the design, manufacture, and installation of undersea communication systems rely on a remarkable intersection of technologies. The technologies supporting this industry have progressed significantly in many aspects. In 1965, coaxial analog systems were transmitting 128 three-kilohertz channels that were amplified by vacuum-tube-based amplifiers for consortiums of national telephone companies over simple point-to-point links. Today, a fiber-optic cable transmits 10 million times as much traffic, that is, tens of terabits of information per second, amplified by reliable erbium-doped fiber amplifiers, as part of mesh networks serving datacom, offshore oil and gas facilities, and scientific applications, each under a variety of ownership and operational models. Installation technology has changed along with the transmission technology, with advances in cable route surveys, ship positioning, cable burial, and use of remotely operated vehicles. System maintenance has become a much more practical endeavor since the advent of universal joint technologies and methodologies. Wet-mateable fiber-optic connectors enable remote, modular, subsea connection scenarios that serve a variety of applications. This paper reviews some of the history and evolution of the technology used in undersea cable systems and addresses future industry trends.

The market for ship repair facilities in the port of Cape town

The market for shiprepair worldwide is segmented according to the purpose for which ships are used, the types and sizes of ships and geographic areas or the routes plied. Shiprepairers tend to focus on the segments in which they have advantages of comparative cost and/or infrastructure and equipment. Generally, Cape size bulk carriers and Post-Panamax container ships are serviced in docks in Asia and tankers above the Afromax size in the Middle East, while the European shiprepairers provide specialised repair services for smaller ships in niche markets. Shiprepairers elsewhere compete in segments of the remainder of the market. The current demand for shiprepair requiring the use of the drydocks and syncrolift at the Port of Cape Town is largely for the repair of ships used for fishing, mining, supply and services, coastal patrol, salvage, rescue and pleasure (passenger vessels) as well as harbour craft and cable ships. Most of the trading ships repaired, apart from those requiring emergency repairs, are small coasters. Few ships involved in international trade have been drydocked for routine survey and repairs in recent years and such business seems to have been lost to Cape Town mainly because it is not a terminal port for regular voyages. The development of the shiprepair industry is an important target in the maritime sector of the National Development Plan of South Africa. In this article conclusions are reached about the complexity of the business economic difficulties of doing so and the prospects for promoting the plan at Cape Town. In view of the lack of academic literature in South Africa on shipping topics notwithstanding the dependence of a country’s economy on its maritime trade, the article is also intended to induce further research on the topic

Tension Analysis of Submarine Cables during Laying Operations

This paper presents a semi-analytical approximation for a two-dimensional (2D) tension analysis of submarine cables during laying operations. In the analysis, based on geometric compatibility relations and equilibrium equations, a set of non-linear differential equations are obtained. The present model considers effects of ocean currents, cable ship motion, pay-out rate, water depth and material properties on submarine cable behavior in water, which are crucial during laying operations. As shown in numerical examples, with consideration of currents and cable ship motion, the cable tension appears to be smaller and cable configuration curve tends to be fatter than the conventional catenary theory.

Edward Stuart Mucklow

Edward Stuart Mucklow (“Ted”) was born in Cheltenham, Gloucestershire, on 24 January 1932, son of Drs Stuart and Alex Mucklow, and was educated at Cheltenham Junior School, Radley College, Exeter...

Cable Ship for Global Optical Submarine Networks

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A new active volcano in the Tyrrhenian Sea?

A strong earthquake occurred in 2002 offshore from the northern coast of Sicily in the Southern Tyrrhenian Sea (Italy), and was followed by a series of hundreds of aftershocks. Communications through the fibre-optic cable between Palermo and Rome were interrupted a few hours after the occurrence of the main shock. After the required technical checks, the failure point was found a few kilometres away from the seismic sequence area. A few days later, a specialised cable ship reached the failure area. One side of the cable was completely burnt, while about three kilometres of cable was found locked. Tests on slices of cable showed that the temperature at which the cable was heated went well above 700oC. We can speculate that the earthquakes triggered off the emission of a submarine lava flow that buried, trapped and burnt the fibre-optic cable. The revising of the bathymetric survey made before the cable’s deployment allowed for the identification of a seamount in the vicinity of the rupture. This structure could represent the lava flow’s source volcano.

John Alexander Dew

After taking his finals during air raids and completing his junior doctor posts at The London Hospital, John Alexander Dew spent three years as a doctor for the merchant navy...

Dynamic analysis of ROV cable considering the coupling motion of ROV cable systems

Remotely Operated Vehicle of 6000-meters is a new conceptual equipment made to replace the manned systems for investigating the deep-sea environment, and all of the ROV systems in operational condition strongly depend on the connecting cables. In this point of view dynamics of the ROV cable system is very important for operational and safety aspects as a cable generally encounters great tension. Researches have been executed on this problem, and most of papers have been mainly focused on the operational condition of ROV system in deep sea. This paper presents the dynamic cable response analysis during ROV launching condition rather than the operational one in order to provide the design guide of a ROV cable system in this circumstance, considering the coupling effects between cable and wave-induced ship motion. To obtain the variations of cable tensions during a ROV launching, a pre-stressed harmonic response analysis was carried out. Wave-induced tensions of the cable during ROV launching were obtained in real sea states using FE modeling, and the basic design guide of a ROV cable system was obtained.

Three dimensional transient analysis of the installation of marine cables

A numerical solution for the three dimensional transient motion of a marine cable during installation is presented for the case of a cable laying vessel arbitrarily chaning speed and direction while paying out cable with seabed slack. The cable transient behaviour is governed by the numerical solution of a set of non-linear partial differential equations with the solution methodology incorporating both spatial and temporal integration. The space integration is carried out by dividing the cable inton straight elements with equilibrium relationships and geometric compatibility equations satisfied for each element. The position of each element is described by its elevation and azimuth angles and, therefore, a system of 2n non-linear ordinary differential equations is established. The time integration of this set of equations is performed using a high order Runge-Kutta technique. Results are presented fro the cable tension and element elevation and azimuth angles as functions of time and for transient cable geometries when the cable ship executes horizontal planar manoeuvres.

The transient behaviour of marine cables being laid—the two-dimensional problem

This paper presents a numerical model for the transient behaviour of marine cables during laying operations. The solution methodology consists of dividing the cable into n straight elements with equilibrium relationships and geometric compatibility equations satisfied for each element. The system of n non-linear ordinary differential equations is then solved by fourth- and fifth-order Runge-Kutta formulae. Results are presented for the cable element slope, cable-top tension, suspended length and required pay-out rate as functions of time and for the cable configuration when the cable ship accelerates or decelerates rectilinearly. The results indicate the necessity of considering the cable dynamics in such analyses, particularly for high cable laying speeds.

Transient behaviour of towed marine cables in two dimensions

This paper presents a numerical solution for the transient motion of marine cables being towed from a cable ship which is changing speed. The cable ship is assumed to move rectilinearly, hence the cable configuration is two-dimensional. The solution methodology consists of dividing the cable into n straight elements with equilibrium relationships and geometric compatibility equations satisfied in each element. A system of n non-linear ordinary differential equations is derived from this and then solved by fourth- and fifth-order Runge—Kutta formulations with the dynamic axial tension calculated iteratively because it is itself dependent on the solution. Results are presented for the cable-top tension and element angles as functions of time and for transient cable geometries when the towing velocity is linearly or parabolically increased (or decreased). It is shown that the results from this analysis compare reasonably well with full-scale experimental data from Hopland (Proc. Int. Wire and Cable Symp., 1993, pp. 734–39).

Francis Thomas Bacon, 21 December 1904 - 24 May 1992

Francis Thomas Bacon, known to all his friends as Tom, was a gentleman scientist with impeccable antecedents. He was a direct descendant of Sir Nicholas Bacon, Lord Keeper of the Great Seal in the time of Queen Elizabeth I. Sir Nicholas’s son by his second marriage was Sir Francis Bacon (1561-1626), Lord Keeper of the Great Seal in the time of James the First, the author of Bacon’s Esay, Novum Organum, The New Atlantis , etc., who became Baron Verulam, Viscount St Albans. He persuaded his contemporaries that a scientific society should be founded in England; this led to the formation of the Royal Society itself. It is also quite possible that Tom was a descendant of the family of Roger Bacon of Oxford (1214-1294) who also was a pioneer of science. Tom Bacon was born at Ramsden Hall, Billericay. His father, Thomas Walter Bacon (1863-1950) was an electrical engineer who, during the later years of the last century, had worked for the Eastern Telegraph Company, both in their workshops in London and in their cable ships. He encouraged his sons to aim for careers in science and engineering. Tom was educated first at St Peters Court Preparatory School in Broadstairs Kent; he had hoped for a career in the Royal Navy but was turned down for Osborne at the age of 12 owing to failing the eyesight test. He then went on to Eton from 1918 to 1922, gaining the School Physics Prize in 1922. From Eton Tom went up to Trinity College, Cambridge, taking the Mechanical Sciences Tripos in 1925. It was while he was at Cambridge that Bacon realized the significance of the Carnot limitation on the thermal efficiency of heat engines and this was to influence almost the whole of the rest of his life.

Proposal for a commercial interconnection among the Hawaiian islands based on the results of the Hawaii Deep Water Cable program

A technical proposal for a commercial interconnection among the islands of the Hawaiian archipelago is described. Within the framework of the Hawaii Deep Water Cable program, this proposal is the link between the previous feasibility studies, development work and the potential future practical realization of the project. Thermal, electrical, mechanical, hydraulic, corrosion, and length aspects were considered for both fluid filled and paper impregnated cables which are likely to be installed in different portions of the approximately 250 km length connection. Considerations are also presented for the requirements of the cable ship having a 12 m sheave diameter, and 7000 t capacity for the rotating platform. The feasibility of manufacturing, transporting and laying such cables within a practical schedule is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Three Dimensional Dynamic Analysis for Laying and Recovery of Optical Submarine Cables

The author has developed two types of cable laying simulation programs based on three dimensional dynamic analysis method in order to analyze dynamic behavior of cables, repeaters and branching unit during laying and recovery.One is a computer simulation program for laying and recovery of submarine cables with repeaters. This program has following two new functions is addition to conventional cable laying simulation.(1) Slack control laying function. The cable pay-out speed is automatically calculated by internal feed back loop so as to make bottom cable slacks be constant. Using this function, the optimum cable pay -out speed history can be obtained by giving the bottom profile and cable ship speed profile.(2) Tension control laying function. The cable pay-out speed is automatically calculated by internal feed back loop so as to make shipboard tension be constant. The speed error of cable ship measured by 'taut wire' is discussed using this program. This error is exactly analyzed using this tension control laying simulation.The other is a computer program for laying and recovery submarine cables with a cable branching unit. The cable branching unit (BU) is newly installed to the optical submarine cable systems. This newly developed program can analyze dynamic behavior of BU and cables around it, and help to study how to lay BU with sufficient cable slacks and recover it safety.The sea trial was carried out in order to measure hydrodynamic constant of the submarine cable and verify this computer simulation method at the depth of 6000m by attaching sensors to the submarine cable at some intervals. According to the sea trial, the normal drag coefficient Cd was measured to 2.5, andd the cable configuration measured by this experiment was in good agreement with the result of the computer simulation.

First sea trial of FSK heterodyne optical transmission system using polarisation diversity

Operation of an FSK heterodyne optical transmission system on the cable ship during the cable-laying, holding, and recovering process in a 6000 m-deep sea trial is demonstrated. It is shown that polarisation diversity is a powerful technique for application to coherent systems in submarine cable systems.

Submarine cables and cable ships

Despite the proliferation of communications satellites there will always be a place for that original medium for intercontinental communication — the submarine cable. This article presents a short history of the cables and the ships that layed them