Birem of the Imperial Age (50 AD). Taken from a bas-relief.
Birem of Claudius Pulcher (220 BC). Syracuse, first Punic War.
The Dikrotus was the other name of this relatively light ship (by Roman standards). It combined a more powerful driving force than the pentecontore in a reduced space precisely thanks to its staging of apostis (openings allowing the passage of the oars). Unlike the Tremes, the biremis was generally open. On the other hand, the Roman Birme was much heavier than its Greek equivalent, and that the Carthaginian ships. It is doubtful whether these vessels were dry-pitched on ramps. They were built of oak, according to the writings found, sometimes with a golden sculpture, but always with a spur (or Rostre), endowed with a small tent (La Diacta, ancestor of the "carosse") for The shelter of his captain, the Magister Navis, a trierarch in Greek. On these light galleys (one man per oar), the troops were reduced, owing to the narrow gangway between the rowers, and their military value was diminished.
However, there is "bireme" and "bireme". Terms may become misleading. In the "Gaul War", Caesar succinctly describes his galley-admiral, mentioning a complete bridge, hundreds of rowers, heavy weapons (balistes and catapults embarked), not to mention the corvus - Assault, dolphins (lead spikes hoisted to yards) and two archers' towers. Only the dimensions are unknown to us, but it seems obvious that this type of galley was a "false bireme" (although actually two rows of oars), and a real Heptère or Octere, ie both rows Of oars were to be handled by 3 or 4 men. The Biremes of this type were around 60-70 meters and embarked a cohort...
This configuration adopted by the Greeks during the Alexandrine period made it possible to devise acceptable dimensions, especially in terms of height on water, which facilitated all the more The maneuvering of the oars, heavy and long. But the biremes, at the time of the empire began to disappear in favor of moners with two rowers by oars (Liburnes, Hemioliae ...) at the origin of the medieval galleys. The bireme still had good days before it, under the name of Dromon, until the fall of Constantinople.