Title
Intelligent Ship to Ship Mooring
Author
Van Acht, J.J.
Contributor
Huijsmans, R.H.M. (mentor)
Faculty
Mechanical, Maritime and Materials Engineering
Department
Marine and Transport Technology
Date
2016-07-26
Abstract
Mampaey Offshore Industries is currently developing an Intelligent DockLocking System (iDL), an automatic magnetic mooring system. A promising design case for iDL is ship to ship mooring in the port of Singapore. Ship to ship mooring operations are abundant and the port of Singapore is known as progressive and well willing to adopt innovativemaritime solutions. Applying iDL mooring instead of conventional mooring techniques could increase safety of mooring procedures, decrease mooring time, decrease mooring labor intensity and improve mooring operability. To achieve these goals, iDL has to withstand environmental conditions as they appear in Singapore. The aim of this thesis is to investigate if the current iDL system is able to execute ship to ship mooring operations in Singapore and if not, what improvements to iDL should be made. The following design case is defined: A 110m LNG Carrier (LNGC) is moored using iDL to a 290m Floating Storage and Regasification Unit (FSRU). Several environmental conditions have been investigated and it is concluded that above wind, wave and current loads, passing vessel loads are most critical in this ship to ship mooring operation. Hence, the following design load is defined: A 320m container vessel passes by at a distance of 100m with a velocity of 10kts. In order to incorporate the non-linear passing vessel forces, a 2 body coupled 12 Degrees of Freedom (DOF) time domain model is created. In this model iDL is implemented as an uncoupled 3 DOF spring damper system. After evaluating force and motion behavior of the current iDL, it turns out that the system in its current state is incapable of withstanding the impact of a passing vessel. Both iDL force and motion limits in surge and sway are exceeded. To improve force and motion behavior in sway, the iDL sway stiffness, damping and pretension are optimized. Pretension turns out to be the key parameter. A pretension of 125 kN is just high enough to maintain fender contact during the entire passing vessel motion, which results in minimumsway forces and motions. Secondly, optimum surge spring and damper coefficients of iDL are studied. Two types of optima can be determined. In case the surge spring coefficient of iDL is 500 kN/m (or higher), quasi-static motion behavior is obtained. Both surge motions and forces reach a minimum. A second minimum is found when iDL behaves as a purely damped system in surge. In case the LNGC is moored to the FSRU using iDL as described above, the resulting maximum iDL surge and sway forces are 120.5 kN and 131 kN respectively. If in a future system sufficient magnetic capacity is present to withstand these loads, iDL proves to be a feasible mooring solution.
Subject
passing vessels
dynamic mooring
time domain
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Embargo date
2026-07-26
Part of collection
Student theses
Document type
master thesis
Rights
(c) 2016 Van Acht, J.J.