The Early Successors of Alexander gave a boost in the use and the development of the polyeres-type warships (multimeremes), using them widely in their wars (321 BC – early 3rd century BC). The Successors have built fleets comprised of numerous large warships, reaching the building of colossal vessels such as the ‘eikoseres’ (20reme, with twenty oarsmen on each vertical group of oars) and the enormous ‘tessarakonteres’ (40reme, with forty oarsmen on each vertical group of oars). These warships resembled to floating fortresses, very similar in size to the modern large battleships and aircraft carriers. The tessarakonteres had a crew of 6.000 men (officers, oarsmen, sailors, marines and others), as many as a modern aircraft carrier.

Tessarakonteres (Greek: τεσσαρακοντήρης, "forty-rowed"), or simply "forty" was a very large catamaran galley reportedly built in the Hellenistic period by Ptolemy IV Philopator of Egypt. It was described by a number of ancient sources, including a lost work by Callixenus of Rhodes and surviving texts by Athenaeus and Plutarch. According to these descriptions, supported by modern research by Lionel Casson, the enormous size of the vessel made it impractical and it was built only as a prestige vessel, rather than an effective warship.

The name "forty" refers not to the number of oars, but to the number of rowers on each column of oars that propelled it, and at the size described it would have been the largest ship constructed in antiquity, and probably the largest human-powered vessel ever built.

The maximum practical number of oar ranks a ship could have logistically was three (Greek and Latin tri-). Beyond three, the number in the type name did not refer to the number of ranks of oars any more (as for biremes and triremes, respectively two and three ranks of oars with one rower per oar), but to the number of rowers per vertical section, with several men on each oar. Indeed, just because a ship was designated with a larger type number did not mean it necessarily had or operated all three possible ranks: the quadrireme may have been a simple evolution of a standard trireme, but with two rowers on the top oar; it may also have been a bireme with two men on each oar; or it may just have had a single rank with four men on a each single oar. Classes of ship could differ in their configuration between regions and over time, but in no case did a "four" ship have four horizontal ranks of oars.

As a catamaran of two "twentys" with 4,000 oarsmen, there would be 2,000 per hull and therefore 1,000 per side. The 130m length would allow ample room for the 50 vertical sections of three oars each, with each vertical section accommodating 20 rowers (hence the designation "twenty"). Thus there would be 150 oars per side. Casson has suggested that it was possible that the two internal sides were not equipped with oars and that the rowers there acted as reserve crew for those on the outer side, so the "forty" would have had either 300 or 600 oars.