Underkeel Clearance Forecast for LNG Carriers in an Access Channel with Beam Swells

van der Molen W.; Taylor D.; Scott D.; Salinas J.L. · Australasian Coasts and Ports 2021 - Proceedings (2022)

Resumen

The Peru LNG terminal is an LNG export facility on the Peruvian coast. The marine terminal is comprised of an LNG loading jetty protected by a detached breakwater with arrival and departure channels on either side of the breakwater. The LNG carriers are exposed to beam swells causing them to roll prior to entering the lee zone behind the breakwater on arrival and after exiting protected waters on departure. The minimum underkeel clearance (UKC) for arriving and departing vessels occur in the roll zone. An extensive dataset of Portable Pilot Unit (PPU) data with over 400 channel transits was analysed to better understand the roll behaviour of vessels in the channel. The PPU and wave buoy data were used for model calibration. It was found that the roll period of conventional membrane LNG carrier with a capacity of 137,000 m3 to 173,400 m3 is 13-14 s in ballast and 15-17 s laden, which is within the range of swell periods experienced at the site. A UKC forecast system was developed and integrates the calculation of vessel roll with prediction of all other UKC components. The UKC forecast is implemented together with the terminal’s moored ship forecast system to provide an integrated 16-day metocean, mooring and UKC forecast system that is used to schedule vessel visits to the terminal allowing safe arrival transit, berthing, mooring, LNG loading and departure.