ROV SuBastian Dive Reports

Deep Coral Diversity at Emperor Seamount Chain 2019. **NOTE** ROV positioning data from cruise FK190726 is erroneous. The USBL head was damaged, and a second USBL head was deployed over the side from a crane. The motion data that would normally be used in positioning beacons was not appropriate - as the ship rolled the suspended head would simply move up and down in the water yet the system was assuming that it was angling with the ship. This meant that the true position of the vehicle was never accurate for horizontal/vertical positioning. This includes the Pilot's Choice positioning from GreenSea, as it gets data from the USBL system. The rough position, ie Western slope of a particular seamount, is fine but offsets of up to 500m were observed.