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Mooring Systems of Floating Offshore Structures for Emerging Industries

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A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Marine Environmental Science".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 15709

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Special Issue Editors

Dr. Nagi Abdussamie

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Guest Editor

Australian Maritime College, University of Tasmania, Launceston, TAS 7250, Australia
Interests: offshore renewable energy structures (wind and wave); computational fluid dynamics; flow in porous media; wave-induced loads on offshore platforms and ships; risk and safety assessment of marine and mechanical systems
Special Issues, Collections and Topics in MDPI journals

Prof. Shuhong Chai

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Guest Editor

Australian Maritime College, University of Tasmania, Launceston, TAS 7250, Australia
Interests: maritime hydrodynamics; floating offshore structure motion responses; mooring line and flexible riser system design; manoeuvring of surface and underwater vehicles

Special Issue Information

Dear Colleagues,

Current offshore renewable energy (e.g., wind, waves, and tidal energy) and aquaculture (e.g., fish, seaweed, and mussel farming) practices require large structures to be installed offshore. Floating structures such as semisubmersibles, SPARs, TLPs, barges, and ship-shaped platforms can be feasible options for commercial developments in deep-water locations where fixed-bottom structures become uneconomical in such emerging industries. A key element of these floating structures is the mooring system, which is the subject covered in this Special Issue. Moorings can significantly affect rigid body motions and, in turn, the performance of a floating system and are solely responsible for station-keeping during extreme weather events. Accurately assessing a structure’s dynamics and mooring responses in operational and survivable conditions is critical when developing a new technology that can consistently produce sustainable energy/seafood or other products across a wide range of conditions yet mitigate the risk associated with a severe storm. Recent accidents due to extreme weather events have highlighted the risk that improper design of these structures and/or mooring systems can have on the structure’s integrity and the marine environment.

This Special Issue aims at bridging the knowledge transition between offshore oil and gas and other emerging industries for reliable and sustainable mooring design and analysis of floating offshore renewable energy and aquaculture structures.

Dr. Nagi Abdussamie
Prof. Shuhong Chai
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Theoretical developments in mooring design, analysis, and optimization
Numerical simulations for moorings
Model tests for moorings
Mooring fatigue analysis
TLP: ringing and springing
Anchor selection for mooring design
Mooring materials
Mooring installation techniques
Mooring inspection and monitoring techniques
Mooring reliability and integrity management

Published Papers (4 papers)

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Research

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17 pages, 3482 KiB

Open AccessArticle

Time and Frequency Domain Dynamic Analysis of Offshore Mooring

by Shi He and Aijun Wang

J. Mar. Sci. Eng. 2021, 9(7), 781; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9070781 - 19 Jul 2021

Cited by 3 | Viewed by 2333

Abstract

The numerical procedures for dynamic analysis of mooring lines in the time domain and frequency domain were developed in this work. The lumped mass method was used to model the mooring lines. In the time domain dynamic analysis, the modified Euler method was used to solve the motion equation of mooring lines. The dynamic analyses of mooring lines under horizontal, vertical, and combined harmonic excitations were carried out. The cases of single-component and multicomponent mooring lines under these excitations were studied, respectively. The case considering the seabed contact was also included. The program was validated by comparing with the results from commercial software, Orcaflex. For the frequency domain dynamic analysis, an improved frame invariant stochastic linearization method was applied to the nonlinear hydrodynamic drag term. The cases of single-component and multicomponent mooring lines were studied. The comparison of results shows that frequency domain results agree well with nonlinear time domain results. Full article

(This article belongs to the Special Issue Mooring Systems of Floating Offshore Structures for Emerging Industries)

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20 pages, 8508 KiB

Open AccessArticle

Water Depth Variation Influence on the Mooring Line Design for FOWT within Shallow Water Region

by Wei-Hua Huang and Ray-Yeng Yang

J. Mar. Sci. Eng. 2021, 9(4), 409; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9040409 - 12 Apr 2021

Cited by 15 | Viewed by 4606

Abstract

The objective of this paper was to present the modeling and optimization of mooring lines for floating offshore wind turbines (FOWT) located in various water depths from 50 m to 100 m in Taiwan western offshore areas. A semi-submersible floating wind turbine system is considered based on Offshore Code Comparison Collaborative Continuation (OC4) DeepCwind platform with the National Renewable Energy Laboratory (NREL) offshore 5-MW baseline wind turbine. The mooring lines proposed consist of a catenary mooring with studless chains. Three nominal sizes of the mooring chain links are taken into account with diameters of 95 mm, 115 mm and 135 mm. According to this configuration, a total of five mooring designs for different water depths (i.e., 50 m, 60 m, 70 m, 80 m, 100 m) are analyzed according to the rules and regulations of the two certification institutions, Det Norske Veritas (DNV) and American Petroleum Institute (API). Considering ultimate limit state (ULS), fatigue limit state (FLS) and maximum operating sea state (MOSS) based on a typhoon with a 50-year return period and current with a 10-year return period, 25-year design life, as well as 1-year return period, respectively, long-term predictions of breaking strength, fatigue and stability are performed. The software OrcaFlex version 10.3 d is used to simulate and design the mooring lines. The obtained results show that the shallow mooring design of 50 m water depth case presents the heaviest chains among the other water depths, increasing their mooring costs. On the other hand, the 100 m water design has much longer mooring lines, making this parameter the cost driving one. Thus, the minimum mooring cost range is from 60 m to 80 m water depth. Full article

(This article belongs to the Special Issue Mooring Systems of Floating Offshore Structures for Emerging Industries)

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22 pages, 6618 KiB

Open AccessArticle

Mooring Analysis of a Floating OWC Wave Energy Converter

by Alana Pols, Eric Gubesch, Nagi Abdussamie, Irene Penesis and Christopher Chin

J. Mar. Sci. Eng. 2021, 9(2), 228; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9020228 - 20 Feb 2021

Cited by 11 | Viewed by 3822

Abstract

This investigation focuses on the modelling of a floating oscillating water column (FOWC) wave energy converter with a numerical code (ANSYS AQWA) based on potential flow theory. Free-floating motions predicted by the numerical model were validated against experimental data extrapolated from a 1:36 scale model device in regular and irregular sea states. Upon validation, an assessment of the device’s motions when dynamically coupled with a four-line catenary mooring arrangement was conducted at different incident wave angles and sea states ranging from operational to survivable conditions, including the simulation of the failure of a single mooring line. The lack of viscosity in the numerical modelling led to overpredicted motions in the vicinity of the resonant frequencies; however, the addition of an external linear damping coefficient was shown to be an acceptable method of mitigating these discrepancies. The incident wave angle was found to have a limited influence on the magnitudes of heave, pitch, and surge motions. Furthermore, the obtained results indicated that the mooring restoring force is controlled by the forward mooring lines under the tested conditions. Full article

(This article belongs to the Special Issue Mooring Systems of Floating Offshore Structures for Emerging Industries)

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Review

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34 pages, 10244 KiB

Open AccessReview

Composite Springs for Mooring Tensioners: A Systematic Review of Material Selection, Fatigue Performance, Manufacturing, and Applications

by Yuanzhen Cai, Milad Bazli, Asanka P. Basnayake, Martin Veidt and Michael T. Heitzmann

J. Mar. Sci. Eng. 2022, 10(9), 1286; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10091286 - 12 Sep 2022

Cited by 3 | Viewed by 2411

Abstract

Ocean energy is an underutilized renewable energy source compared with hydropower and wind power. Therefore, the development of economical and efficient wave energy converters (WECs) is important and crucial for offshore power generation. The mooring tensioner is a critical device that can be used in point-absorber-type WECs, semisubmersible floats for oil and gas drilling, and floating wind turbines. A mooring tensioner is a system used to create, reduce, or maintain tension within the mooring lines by applying a force to the mooring line. Composite springs as mooring tensioners have several advantages compared to metal springs, such as corrosion resistance, high specific strain energy, appropriate fatigue performance, and the ability to flexibly adjust the spring constant without changing the overall dimensions. This paper reviews in detail the fatigue performance, seawater durability, and manufacturing methods of different composite materials as well as the current and potential applications of composites springs. In addition, recommendations for future research and opportunities for composite mooring tensioners are presented. Full article

(This article belongs to the Special Issue Mooring Systems of Floating Offshore Structures for Emerging Industries)

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