Doug is one of SpaceX’s two new multi-purpose recovery ships. Alongside identical sister ship Bob, the two are designed for both fairing and booster recovery operations.
Doug was converted from a former platform supply ship – a kind of mini cargo ship designed to serve offshore platforms – from May to August 2021 in Louisiana. The most obvious change is a large crane that has been added. The crane has an estimated boom of around 45 meters and will be used to lift fairing halves from the water, following soft-splashdown under parafoil control. Until February 2021, SpaceX was using two custom fairing catcher ships named Ms. Tree and Ms. Chief.
Tree and Chief were fast and dynamic vessels that were equipped with large nets that would try to catch fairing halves before they hit the water. This recovery method was ultimately abandoned after proving unreliable and SpaceX temporarily brought in contracted ships with cranes to recover halves. This alternative method proved a success and likely influenced the design of Bob and Doug.
Doug is also designed to tow and support droneships offshore. The ship is equipped with a large towing winch underneath a raised platform. This winch will be used to pull in the droneship towing line so that Doug can tow the ASDS. SpaceX is working towards full droneship autonomy with A Shortfall of Gravitas already equipped with it and Just Read the Instructions being upgraded.
Doug would be able to tow the droneship to and from Port Canaveral and then release the droneship once offshore. Before these optimisations, SpaceX droneships were towed by a contracted tugboat, often Tug Finn Falgout. The droneship would only be autonomous during landing operations and towed at all other times. A second vessel, GO Quest, would shadow the droneship, carrying crew and equipment to secure boosters post-landing.