Engineering Performance and Spatial Models Highlight Key Considerations for Supporting Broadscale Replacement of Environmentally Sensitive (ES) Vessel Moorings
Creators: name: Wong, Lincoln S.
name: Martini, Andrew
name: Lynch, Tim P.
name: Devine, Carlie
name: Hardiman, Lauren
name: McEnnulty, Felicity R.
name: Stuart-Smith, Rick D.
name: Ross, D. Jeff
Publisher: name: Taylor & Francis
Year: 2025
Subjects: subject: Biochemistry
subject: Genetics
subject: FOS: Biological sciences
subject: Evolutionary Biology
subject: Environmental Sciences not elsewhere classified
subject: Ecology
subject: Astronomical and Space Sciences not elsewhere classified
subject: Biological Sciences not elsewhere classified
subject: Science Policy

description: Chain moorings are widely used for securing vessels in coastal zones worldwide but can cause environmental damage to the seabed. Although Environmentally Sensitive (ES) mooring alternatives are available, wide-scale adoption and replacement of existing chain moorings have been limited. Adoption may have been hindered by a lack of information relating to the performance and movement characteristics of ES moorings in contrast to chain moorings. The engineering performance of both chain and ES moorings, including tension loading and horizontal movement, was explored using a quasi-static time series model. The performance of chain moorings depended on weather conditions; in simulated extreme weather conditions, chain moorings experienced a surprisingly high tensile load, more than double (118%) the working load limit. However, in mild weather conditions, chain moorings had the lowest tension loads compared to all tested designs. ES moorings experienced lower peak loads compared to chain moorings (47%–61%) in extreme weather but had higher base loads in mild conditions. The lighter, neutrally buoyant mooring line of ES moorings resulted in an increased movement range of the moored vessels under both weather scenarios. Additionally, this study modeled the clearance between ES moorings and neighboring chain moorings, which can be critical knowledge for planning the replacement of only some chain moorings within existing mooring fields. Using an existing mooring field as a case study, only 18% of the moorings have sufficient clearance with their neighboring moorings to be replaced with ES moorings. This study identified better load handling performance of ES than chain moorings under extreme weather conditions, suggesting when designed properly, ES moorings can function as intended to moor vessels. Yet the difference in clearance requirement between mooring designs indicates that careful planning is needed when replacing individual moorings with ES mooring in dense mooring fields. Replacement of chain moorings will need to incorporate a wider spatial perspective, considering differences in movement and spacing required between moorings to minimize the risk of contact between moored vessels. ES moorings could be effective both in their ability to conserve benthic habitats and at securing vessels in extreme conditions, however, the replacement process will require an adaptive management approach and careful consideration of mooring engineering requirements and mooring field spacing.