Deck officers or mates perform the watch duties on board of vessels like determining the course and speed, manoeuvring to avoid hazards, and continuously monitoring the vessels position using charts and navigational aids. They maintain logs and other records tracking the ship's movements. They ensure that the proper procedures and safety practices are followed, check that equipment is in good working order, and oversee the loading and discharging of cargo or passengers. They supervise crew members engaged in maintenance and the primary upkeep of the vessel.