Mathematical modelling of forces acting on ships during lightering operations

Lataire, Evert; Vantorre, Marc; Delefortrie, Guillaume; Candries, Maxim

doi:10.1016/j.oceaneng.2012.07.029

Cited by 40 publications

(35 citation statements)

References 4 publications

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“…Some ambitious plans of port expansion have been proposed to overcome this problem but it is not a feasible solution due to land constraints. Currently, the ship-to-ship transfer operations mainly involve the transfer of liquid cargos [4]. The idea of offshore ship-to-ship transfer of containers and delivering them to conventional harbours can minimize the port congestion and eliminate the need of outward expansion of these container ports.…”

Section: Introductionmentioning

confidence: 99%

Modelling and robust trajectory following for offshore container crane systems

Ismail

That

2015

Automation in Construction

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Section: Introductionmentioning

confidence: 99%

Modelling and robust trajectory following for offshore container crane systems

Ismail

That

2015

Automation in Construction

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“…Based upon this extensive model test program a mathematical model for the yaw moment induced by the proximity of the VLCC on the service ship (Aframax) is presented in Lataire et al (2012). In open water (deep and shallow) multi-modal model tests are carried out with a varying rudder angle.…”

Section: Discussionmentioning

confidence: 99%

“…The mathematical model for the yaw moment induced during a lightering manoeuvre to be published in Lataire et al (2012) is:…”

Section: Rudder Angle and Yaw Momentmentioning

confidence: 99%

“…An almost insignificant influence of the water depth on the resulting yaw moment is seen. Based upon the mathematical model for the yaw moment as proposed in Lataire et al (2012) and equations (4) and (5), a graph can be plotted for a wide range of relative positions (both longitudinal and lateral) between the service ship and the STBL displaying the rudder angle required to compensate the yaw moment induced during a lightering manoeuvre (Figure 7).…”

Section: Fig 5 Yaw Moment Induced On the Service Ship By The Ruddermentioning

confidence: 99%

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Controlling the Yawing of an Aframax Tanker During a Lightering Manoeuvre

Lataire

Delefortrie

Vantorre

2012

IFAC Proceedings Volumes

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Lightering is the process where a larger ship (the ship to be lightered, STBL) transfers (parts of) its cargo to a smaller vessel, known as service ship. This transfer occurs at a slow sailing speed (about 4 knots) while both ships are moored to each other. A knowledge-building project with user involvement entitled "Investigating Hydrodynamic Aspects and Control Strategies for Ship-to-Ship Operations" was carried out in 2007-2011 to offer more insight in lightering operations. The actual forces acting on both vessels while preparing for lightering can be analysed based upon more than two thousand captive model tests carried out at the Towing tank for manoeuvres in shallow water (co-operation Flanders Hydraulics Research -Ghent University) in Antwerp, Belgium. The tests were executed with a scale model of a very large crude oil carrier (VLCC) attached to the main frame of the towing carriage and a scale model of an Aframax tanker attached to the computer controlled planar motion carriage. Forces, moments and vertical positions were measured on both models.In this article particular attention is given to the comparison, in deep and shallow water, of the yawing moment induced on the service ship during the lightering operation and the yawing moment induced by the rudder of the same ship during open water tests. The combination of both allows defining ranges of relative positions between both vessels with an equal degree of controllability of the service ship during the lightering operation. In shallow water, the acceptable meeting area appears to be reduced significantly.

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“…However, it can be seen that expanding outwards is not a feasible option due to land constraints [3]. Consequently, a new method of transportation, the so-called ship-to-ship cargo transfer operation, is introduced [4]. This operation involves the transfer of containers between a huge container ship and a relatively smaller ship, known as a mobile harbour by using an offshore crane mounted on the container ship [5].…”

Section: Introductionmentioning

confidence: 99%

Offshore Container Crane Systems with Robust OptimalSliding Mode Control

Ismail¹,

That²,

Ha³

2014

Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC)

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-Open-sea ship-to-ship transfer operation is an alternative way to avoid port congestion. This process involves a relatively small vessel which transports containers between the harbour and a large cargo ship equipped with a container crane. However, the presence of disturbances and uncertainties caused by harsh open-sea conditions can produce an excessive sway to the hoisting ropes of the crane system. This paper addresses the problem of robust sliding mode control for offshore container crane systems subject to bounded disturbances and uncertain parameters. The mathematical model of an offshore container crane is first derived whereas the effects of ocean waves and gusty winds are taken into account. Then, based on the linear quadratic regulator (LQR) design, a sliding surface is obtained to meet the required performance and stable dynamics for the closed-loop system. Finally, a robust sliding mode controller is proposed to drive the state trajectories of the offshore container crane system towards the sliding surface in finite time and maintain them subsequently on that surface. Simulation results are given to show that the proposed controller can significantly suppress the effects of uncertainties and disturbances from the vessel's wave-and wind-induced motion and wind drag force on the payload.

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Mathematical modelling of forces acting on ships during lightering operations

Cited by 40 publications

References 4 publications

Modelling and robust trajectory following for offshore container crane systems

Modelling and robust trajectory following for offshore container crane systems

Controlling the Yawing of an Aframax Tanker During a Lightering Manoeuvre

Offshore Container Crane Systems with Robust OptimalSliding Mode Control

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