Just Read the Instructions
Just Read the Instructions (JRTI) is an autonomous spaceport droneship (ASDS). JRTI is a modified barge outfitted with a large landing platform, station-keeping thrusters and other equipment to allow SpaceX to land boosters at sea on high-velocity missions that don't carry enough fuel to allow for a return-to-launch-site landing.
Just Read the Instructions was originally based in California to support missions out of Vandenburg. The ship was moved to Florida in late 2019 to support the large number of launches booked to launch out of Cape Canaveral in 2020.
Just Read the Instructions is the second SpaceX droneship to use the name. The original SpaceX droneship, used for 2 experimental landings on the east coast used the same name but was retired and replaced by Of Course I Still Love You. The name was then given to the new droneship destined for the west coast.
JRTI was built in a Louisiana shipyard, alongside the east coast droneship Of Course I Still Love You. To reach its new home in Los Angeles the ship had to pass through the Panama Canal. The droneship was too wide to fit through so the extra wing extensions, designed to provide a larger landing pad, had to be placed on deck to be installed on arrival in LA.
JRTI is built very similarly to OCISLY. The droneship is built on a barge named Marmac 303 and is outfitted with deck extensions (to create a large landing pad), blast protection, cameras, sensors and firefighting equipment.
A key difference between JRTI and OCISLY is that there is no Octagrabber robot on-board JRTI. This means that the blast shielding and stern of the droneship is configured slightly differently as there is no requirement to have a blast-proof garage to store the robot in.
Just Read the Instructions is out-fitted in a similar fashion to Of Course I Still Love You. Four azimuth thruster engines give the droneship the capability to maintain position at sea to within 3 metres using GPS. Cameras and sensors record the landings for analysis and 2 antennas up-link this data to a satellite and allow for communication with the incoming booster. Data up-link often cuts out at the moment of landing because heavy vibrations from the landing shake the antennas out of their lock with the satellite. This video explains more.
SpaceX ASDS's are not capable of moving themselves long distances, with the thruster engines only designed to allow the droneship to maintain position. A tug is used to tow the droneship from port in LA to the landing zone. The precise landing location is dependant on mission requirements.
JRTI and its tug will leave the Port Of LA days in advance of the launch with other accompanying support ships leaving later. Operations at sea are performed in a similar to fashion to OCISLY.
One key difference between landing operations on opposite coasts is that there is no Octagrabber robot on board Just Read The Instructions. SpaceX technicians have to transfer onto the droneship, manually attach support struts and weld them to the deck before they can depart for the port.
West Coast Departure
Just Read the Instructions was towed away from Los Angeles on August 1st 2019, heading for Morgan City, Lousiana. The droneship passed through the Panama Canal on August 18th. Because of the limited width of the Panama Canal locks, the wing extensions of Just Read the Instructions had to be cut off and placed on the deck for the transit. You can see this below.
Just Read the Instructions arrived at Morgan City on August 27th and was berthed at LAD Services Berwick. The ship spent about 4 months there where the side wings were reinstalled and the barge received a general refurbishment. JRTI was then towed to Port Canaveral, Florida - arriving on December 11th, 2019. JRTI arrived with 13 engine units and 6 thrusters on board that had not yet been installed. It is still not clear as to whether all of this equipment is for Just Read the Instructions or if some of it would later be installed onto the Of Course I Still Love You droneship.