Tanker A was underway in a traffic separation scheme (TSS) in good weather and with visibility of about 10 to 12 nautical miles (nm). At approximately 0224, the Master handed over the con and navigational watch to the OOW but remained on the bridge. The OOW on duty had joined the vessel the day before, and this was his first watch. At about 0430, satisfied with the OOW’s familiarity with the vessel and the situation, the Master left the bridge. About 30 minutes later, the vessel was transiting a high-density traffic route and approaching a planned waypoint, which required a course alteration to port of about 50 degrees. The OOW delayed the course alteration to allow a ship on a reciprocal course to pass. Once the ship had cleared, the OOW instructed the lookout to switch to manual steering and alter course. At around 0530, the OOW saw several targets ahead. The OOW consulted the X-band radar and visually identified a ship directly ahead, about 7.6 nm away, with deck lights on but without navigation lights. Two additional ships on reciprocal courses were seen on the starboard bow. The OOW decided to maintain the current course of 018° to allow the vessels to pass safely. At about 0540, the OOW entered the chartroom to prepare various reports. By about 0545, the vessel directly ahead was acquired on X-band ARPA, showing a CPA of 0.18nm in 17 minutes. The OOW informed the lookout/helmsman that as soon as the ship on their starboard side, identified as Target 47, had passed, a course change would be made to increase the CPA of the vessel ahead. The OOW again entered the chartroom. Image for representation purpose only At about 0551, the OOW returned to the wheelhouse. He confirmed Target 47 had cleared to starboard. The vessel ahead (Target 46) was now at 2.9 nm distance, with a CPA of nearly zero in approximately 12 minutes. The OOW made a minor course adjustment of two degrees to starboard. About three minutes later, after confirming that they would clear the vessel a