A Thracian hemiolia, (200 BC), from a description on a Roman bas-relief. The central part is cleared, the space lost being compensated by double strokes.
Trihemiolia Rhodienne, 120 av. J.C. It is a vessel "cataphracte" (entirely bridged), intermediate between a trirem and a teter.
The Hemiolia was a light ship, generally classified in the "aphractoï" (unbounded), peculiar to the pirates of the Aegean Sea (Chios, Lesbos, Lemnos, Sporades and Cyclades) and Asia Minor, Like the Cilicians, contrary to liburnes and lemboi, proper to the Adriatic. The configuration of these vessels remains controversial. They were sailing ships, light, small, but slightly wider than the classic monuments, having one man and more by rowing, unlike the triacontores and pentacontores. The interpretations diverge as to their configuration of rowers: According to John Morrison for example, the Hemiolia would be a monomer in which the oars are handled by two men only in the front and the back, the central part or before having A rower, in order to clear the bridge for the maneuvers of the sail as a place for the combatants.
The Thrace hemiolia above would be even more absolutist, since having two rowers per oars, but none for the central part, totally unobstructed. The dihémiolia would comprise the same system, but in the manner of the dieres in two rows, and the trihemolia, logically that of the triremes, with the difference less oars per flank (not more than 25 like the pentecontore). However, Morrison speaks for the trihemolia of two rows, arguing that dihemia is not mentioned anywhere, unlike Casson who thinks of three rows in this case, but two for the hemiolia, which for him reserves the possibility of To dismantle the central part of its rowers (with a rowing rower) in order to be able to put away the sail and dismantle the mast, which Morrison disputes by arguing that to disembarrass the rowers at the moment when the sail is deposited is precisely illogical.
For Suzanne Ellis, (student) the Hemiolia would have two men by rowing, on one row, but only for half the length ("hemi" means "half"). The trihemiolia would have two rows (it does not speak of dihemiolia). It would be mentioned as the principal ship of Rhodes, probably to better combat piracy and its light vessels, the trihemolia being partially bridged like the Greek triremes. The Greeks (mention for the Athenian fleet) and the Lagids would have disposed of them within their forces.
These ships were considered to be more manageable than triremes. The trihemolia would then not be a galley in which the central part is stripped, but a kind of trireum in which two men handle the upper rowing. (See section), which seems to come very close to a simple variant of the trire. For Michael Williams, another student in maritime archeology, this distribution would go by section, the hemiolia having a single rank but maneuvered by one or two men alternately by section. The trihemiolia would have the same system applied on two rows, see three, and alternately 3/4 men per side, which would make it a ship-in the case of thirty oars per row intermediate between the tether and the trire, and More cataphracte (bridged), far removed from the pirate ships of the Aegean Sea...
My personal opinion is that, in the absence of a real description (bas-relief, mosaic), but according to written indications, these ships must be logically considered taking into account the Greek term "half". Indeed, the solution by alternation of section seems plausible. The hemiolia in this case could be in a configuration of 1/2 alternating rowers per section, dihemia 2/3 (on two rows) and trihemiolia 3/4 on three rows, considering that only pirate hemioliae would have been inspiring , The purely military derivatives (such as the heavy Rhodian trihemiolies, moreover, inventors of the tether, upper echelon), being first-line cataphraw vessels.
I do not see much interest in clearing the central part of the bridge, but on the other hand - as Morrison talks about, the clearance of the front seems more logical. The two solutions (full alternating edge and partial front edge) intersecting the same direction, but with the same difficulty of oars of the same length (obligatory rank), obliging to choose in the chiourme the men strong enough to handle one Rowing done for two. (Were there alternations along the way?). The same problem was repeated for the higher ranks...