The helpless ship was then an easy target, and the ship itself was rammed. Of course the enemy ship must have been hit hard, but not too hard as then there was the chance that the ships got entangled in eachother while the idea was to batter one ship and sail off to the next one. One unhappy slave could mean a disaster, and that is why the rowsmen were recruited among the civilians, instead of using slaves. They came mostly from the poor layers who could not afford the expensive suit of armour of a hoplite. As a rowman they got paid pretty well.
Speed is power.
Modern calculations show that a trireme with a trained crew could reach its topspeed in 30 seconds. After 8 seconds it reached half of this speed, and after 2 seconds it must have done a quarter. A trireme at full speed must have been a fearful sight. The copper battering-ram was often shaped as the nose of a boar, while at both sides of the front often huge eyes were painted and the top of the sides were often covered with pelts. All this together, and the oars which went up and down like huge wings must have given the trireme the look of a gigantic mythological bat.