The deck and command crew (hypēresia) was headed by the helmsman, the kybernētēs, who was always an experienced seaman and was often the commander of the vessel. These experienced sailors were to be found on the upper levels of the triremes. Other officers were the bow lookout (prōreus or prōratēs), the boatswain (keleustēs), the quartermaster (pentēkontarchos), the shipwright (naupēgos), the piper (aulētēs) who gave the rowers’ rhythm and two superintendents (toicharchoi), in charge of the rowers on each side of the ship. What constituted these sailors’ experience was a combination of superior rowing skill (physical stamina and/or consistency in hitting with a full stroke) and previous battle experience. The sailors were likely in their thirties and forties. In addition, there were ten sailors handling the masts and the sails.
Source: Wikipedia