Sunday, July 7, 2013
Roman Trireme - 2
Normally I refuse to build plastic ship kits but this kit was so interesting I couldn't resist.
One thing I've noticed about this kit is the use of 19th century rigging and deck planking.
Oh well these ships are mostly conjecture anyway.
A trireme (derived from Latin: "tres remi:" "three-oar;" Greek Τριήρης, literally "three-oarer") was an ancient vessel and a type of galley, a Hellenistic-era warship that was used by the ancient maritime civilizations of the Mediterranean, especially the Phoenicians, ancient Greeks and Romans.
The trireme derives its name from its three rows of oars on each side, manned with one man per oar. The early trireme was a development of the penteconter, an ancient warship with a single row of 25 oars on each side, and of the bireme (Greek: διήρης), a warship with two banks of oars, probably of Phoenician origin. As a ship it was fast and agile, and became the dominant warship in the Mediterranean from the 7th to the 4th centuries BC, when they were largely superseded by the larger quadriremes and quinqueremes. Triremes played a vital role in the Persian Wars, the creation of the Athenian maritime empire, and its downfall in the Peloponnesian War.
In English, no differentiation is made between the Greek triērēs and the Latin triremis. This is sometimes a source of confusion, as in other languages these terms refer to different styles of ships. Though the term today is used almost exclusively for ancient warships, modern historians also refer to medieval and early modern galleys with three banks of oars per side as triremes. The rowing arrangement of these differed considerably, though, since knowledge of the multi-level structure of the original triremes was lost some time during Late Antiquity.
The exact origin of the trireme is uncertain and debated, as our evidence comes from literary sources, depictions in reliefs and pottery fragments, which are open to misinterpretations. Depictions of two-tiered ships (biremes), with or without the parexeiresia (the outriggers, see below), are common in 8th century BC vases and pottery fragments, and it is at the end of that century that the first references to three-tiered ships are found. According to Thucydides, the trireme was introduced to Greece by the Corinthians in the late 8th century BC, and the Corinthian Ameinocles built four such ships for the Samians. Although this was interpreted by later writers, Pliny and Diodorus, to mean that triremes were invented in Corinth, it is likely that the earliest three-tiered warships originated in Phoenicia. Fragments from an 8th century relief at the Assyrian capital of Nineveh depicting the fleets of Tyre and Sidon have been interpreted as depicting two- and three-level warships, fitted with rams. The 2nd century Christian scholar Clement of Alexandria, drawing on earlier works, explicitly attributes the invention of the trireme (trikrotos naus, "three-tiered ship") to the Sidonians.
Based on all archeological evidence, the design of trireme surely pushed the technological limits of the ancient world. After gathering the proper timbers and materials it was time to consider the fundamentals of the trireme design. These fundamentals included accommodations, propulsion, weight and waterline, center of gravity and stability, strength, and feasibility. All of these variables are dependent on one another; however a certain area may be more important than another depending on the purpose of the ship.
The arrangement and number of oarsmen is the first deciding factor in the size of the ship. For a ship to travel at high speeds would require a high oar-gearing, which is the ratio between the outboard length of an oar and the inboard length; it is this arrangement of the oars which is unique and highly effective for the trireme. The ports would house the oarsmen with a minimal waste of space. There would be three files of oarsmen on each side tightly but workably packed by placing each man outboard of, and in height overlapping, the one below, provided that thalamian tholes were set inboard and their ports enlarged to allow oar movement. Thalamian is the English term for the Greek word, thalamios, which was the name of the oarsmen in the lowest file of the triereis; zygian is the English term for the Greek word, zygios, which were the oarsmen in the middle file of the triereis, and thranite is the English term for the Greek word, thranites, which were the oarsmen in the uppermost file of the triereis. Tholes were pins that acted as fulcrums to the oars that allowed them to move. The center of gravity of the ship is low because of the overlapping formation of the files that allow the ports to remain closer to the ships walls. A lower center of gravity would provide adequate stability.
The trireme was constructed to maximize all traits of the ship to the point where if any changes were made the design would be compromised. Speed was maximized to the point where any less weight would have resulted in considerable losses to the ship's integrity. The center of gravity was placed at the lowest possible position where the Thalamian tholes were just above the waterline which retained the ships resistance to waves and the possible rollover. If the center of gravity were placed any higher, the additional beams needed to restore stability would have resulted in the exclusion of the Thalamian tholes due to the reduced hull space. The purpose of the area just below the center of gravity and the waterline known as the hypozomata was to allow bending of the hull when faced with up to 90kN of force. The calculations of forces that could have been absorbed by the ship are arguable because there is not enough evidence to confirm the exact process of jointing used in ancient times. In a modern reconstruction of the ship, a polysulphide sealant was used to compare to the caulking that evidence suggests was used; however this is also argued because there is simply not enough evidence to authentically reproduce the triereis seams.
Triremes required a great deal of upkeep in order to stay afloat, as references to the replacement of ropes, sails, rudders, oars and masts in the middle of campaigns suggest. They also would become waterlogged if left in the sea for too long. In order to prevent this from happening, ships would have to be pulled from the water during the night. The use of lightwoods meant that the ship could be carried ashore by as few as 140 men. Beaching the ships at night however, would leave the troops vulnerable to surprise attacks. While well-maintained triremes would last up to 25 years, during the Peloponnesian War, Athens had to build nearly 20 triremes a year to maintain their fleet of 300.
The Athenian trireme had two great cables of about 47 mm in diameter and twice the ship's length called hypozomata (undergirding), and carried two spares. They were possibly rigged fore and aft from end to end along the middle line of the hull just under the main beams and tensioned to 13.5 tonnes force. The hypozomata were considered important and secret: their export from Athens was a capital offence. This cable would act as a stretched tendon straight down the middle of the hull, and would have prevented hogging. Additionally, hull plank butts would remain in compression in all but the most severe sea conditions, reducing working of joints and consequent leakage. The hypozomata would also have significantly braced the structure of the trireme against the stresses of ramming, giving it an important advantage in combat.