The Tetrere is a very powerful warship, inferior only to mighty Pentereis and some of the rarer, larger ships.
Basileu, the Tetrereis are very powerful warships and the mainstay of your fleet! And as much as our people would like to claim the credit of their invention, credible historians claim that the first four-row warships were built by skilled shipwrights from Qart-Hadast. We do know that as early as two years after the 95th Olimpiade (398 BC) Dionysos, Tyrannos of Syrakousai had these vessels in his fleet. If You think to achieve Thalassokratia, Arche, then you must add many ships of this design to your navy.
Although the Tetrere made up the bulk of many Hellenistic fleets, its design is still uncertain. The most probable reconstruction states that it had two rows of oars manned by two oarsmen each. The biggest Athenian docks measured 37x6 metres, which suggests that this was the size of the "4" and "5" - the biggest ships we know of that Athens had. If this is true, the crew of a Tetrere would consist of 232 men operating 116 oars. Some iconography suggests the Tetrere was completely boxed-in, with a full deck and covered sides. Also being two-rowed, this ship doesn't require outriggers. On longer voyages, if the wind blew from behind, sails were used (the main sail on the central mast and another on the small mast at the ship's bow). The ship was armed with a ram, had a boarding crew of somewhere below 40 men, and was capable of carrying an additional 60-80 man. Later, some were armed with catapults or ballistae.