From 2006 to 2012 the HAWA-I and HAWA-II Joint Industry Projects provided a better understanding of the effect of infragravity waves on nearshore LNG facilities. This resulted in the development of a methodology to take infragravity waves into account in the design of such a facility in specific nearshore locations. Since then, most new projects consisted of developments in deeper water. However, in recent years the focus of projects in the field has shifted again to shallow water, and the design of LNG terminals in a nearshore environment has become a critical topic again. Also, the design of permanently moored offshore structures in shallow water has been found especially challenging in practice due to the lack of detailed guidelines. Failures of mooring systems have been observed in the field due to infragravity waves, which show that the infragravity waves remain a critical aspect in design methodologies for shallow-water developments.

There are multiple reasons why it remains difficult to take long waves into account in terminal designs, even with the developed dedicated methodology in place. This is mainly because (1) the workflow of the methodology is relatively complex and time-consuming, (2) taking infragravity waves into account is not always a requirement from authorities and regulations, (3) the uncertainties involved in the methodology need to be assessed, (4) the methodology has been developed for open terminal configurations, and is not applicable yet for cases where breakwaters are involved. Furthermore, the physics involved remain quite complex.

OBJECTIVES

The objective of the HAWA-III JIP is to extend and validate the overall design methodology of nearshore terminals based on model scale measurements, and to provide practical tools and guidelines to apply the methodology. The results from the previous two JIP phases will be used as a starting point and they will be expanded to reach this objective.

DELIVERABLES

The JIP is proposed to be executed as a 2.5-year project starting in 2022. The deliverables of the HAWAIII JIP will be as follows:

• Guidance Note from Classification Societies
• Pros and cons of full scale measurement campaigns of infragravity waves
• HAWAIII diffraction tool (as much as possible open-source) to compute wave loads on LNG terminals due to infragravity waves provided by nearshore wave models
• Tutorial to apply the design methodology with and without breakwater
• Validation of the design methodology based on model scale measurements
• Extension of the design methodology to include situations with breakwaters