Up to two SRVs would temporarily moor at the proposed deepwater port by means of a submerged unloading buoy system. Two unloading buoys would be separated by a distance of approximately 3.1 miles. The unloading buoys would moor each SRV on location throughout the unloading cycle. Each unloading buoy would have eight mooring lines consisting of wire rope and chain. The mooring lines would connect each unloading buoy to eight anchor points most likely consisting of driven piles on the seabed. The unloading buoy designed by Advanced Production Loading AS (APL) is also commonly known as Submerged Turret Loading (STL) Buoys.

An SRV would typically moor at the deepwater port for between four and eight days, depending on vessel size and send out rate. The two separate buoys would allow natural gas to be delivered in a continuous flow, without interruption, by scheduling an overlap between arriving and departing SRVs. The unloading buoy technology and associated equipage proposed for Port Dolphin is similar to that used in the Gulf Gateway deepwater port and that is planned for the Northeast Gateway, Neptune and Calypso projects. The technology has also been successfully used at several locations overseas including the North Sea.

When not connected to an SRV, the unloading buoy would be submerged 60-70 feet (18-21 meters) below the sea surface. In this position, the buoy would be held in position by the mooring lines and would be resting on the STL Buoy landing pad. A marker buoy and retrieval line would be used to locate and recover the buoy as the SRV arrives at the deepwater port. The unloading buoy would be retrieved from its submerged position by means of a winch and recovery line. It would be hoisted up through a moon pool in the forward part of the SRV where it would be located in a receiving cone within the hull trunk. After the buoy is locked in position, unloading of natural gas would begin. The gas would be unloaded through the flexible riser into the pipeline end manifold (PLEM) for transportation to shore via the subsea pipeline.

The SRVs would be equipped to transport, store, and vaporize liquefied natural gas and to meter natural gas. The SRV would have insulated storage tanks for the liquefied natural gas located within its hull. Each tank would be equipped with an in-tank pump to circulate and transfer liquefied natural gas, at a temperature of approximately -261 degrees Fahrenheit (- 163 degrees celcius), to the vaporization facilities located on the deck of the SRV. The vaporization system would have a closed loop cycle utilizing glycol/water brine as the recirculating heating medium. This recirculating medium would heat the liquefied natural gas and the medium itself would be warmed using steam from the SRV’s natural gas boilers.