Design Trireme

1 design

1.1 dimensions
1.2 construction
1.3 propulsion , capabilities

design

model of greek trireme



a roman mosaic tunisia showing trireme vessel during roman empire

based on archeological evidence, design of trireme surely pushed technological limits of ancient world. after gathering proper timbers , materials time consider fundamentals of trireme design. these fundamentals included accommodations, propulsion, weight , waterline, center of gravity , stability, strength, , feasibility. of these variables dependent on 1 another; area may more important depending on purpose of ship.

the arrangement , number of oarsmen first deciding factor in size of ship. ship travel @ high speeds require high oar-gearing, ratio between outboard length of oar , inboard length; arrangement of oars unique , highly effective trireme. ports house oarsmen minimal waste of space. there 3 files of oarsmen on each side tightly workably packed placing each man outboard of, , in height overlapping, 1 below, provided thalamian tholes set inboard , ports enlarged allow oar movement. thalamian english term greek word, thalamios, name of oarsmen in lowest file of triereis; zygian english term greek word, zygios, oarsmen in middle file of triereis, , thranite english term greek word, thranites, oarsmen in uppermost file of triereis. tholes pins acted fulcrums oars allowed them move. center of gravity of ship low because of overlapping formation of files allow ports remain closer ships walls. lower center of gravity provide adequate stability.

the trireme constructed maximize traits of ship point if changes made design compromised. speed maximized point less weight have resulted in considerable losses ship s integrity. center of gravity placed @ lowest possible position thalamian tholes above waterline retained ship s resistance waves , possible rollover. if center of gravity placed higher, additional beams needed restore stability have resulted in exclusion of thalamian tholes due reduced hull space. purpose of area below center of gravity , waterline known hypozomata allow bending of hull when faced 90 kn of force. calculations of forces have been absorbed ship arguable because there not enough evidence confirm exact process of jointing used in ancient times. in modern reconstruction of ship, polysulphide sealant used compare caulking evidence suggests used; argued because there not enough evidence authentically reproduce triereis seams.

triremes required great deal of upkeep in order stay afloat, references replacement of ropes, sails, rudders, oars , masts in middle of campaigns suggest. become waterlogged if left in sea long. in order prevent happening, ships have pulled water during night. use of lightwoods meant ship carried ashore few 140 men. beaching ships @ night however, leave troops vulnerable surprise attacks. while well-maintained triremes last 25 years, during peloponnesian war, athens had build 20 triremes year maintain fleet of 300.

the athenian trireme had 2 great cables of 47 mm in diameter , twice ship s length called hypozomata (undergirding), , carried 2 spares. possibly rigged fore , aft end end along middle line of hull under main beams , tensioned 13.5 tonnes force. hypozomata considered important , secret: export athens capital offense. cable act stretched tendon straight down middle of hull, , have prevented hogging. additionally, hull plank butts remain in compression in severe sea conditions, reducing working of joints , consequent leakage. hypozomata have braced structure of trireme against stresses of ramming, giving important advantage in combat.

according professor j.e. gordon: hupozoma therefore essential part of hulls of these ships; unable fight, or go sea @ all, without it. used practice disarm modern warships removing breech-blocks guns, so, in classical times, disarmament commissioners used disarm triremes removing hupozomata.

dimensions

excavations of ship sheds (neōsoikoi) @ harbour of zea in piraeus, main war harbour of ancient athens, first carried out dragatsis , wilhelm dörpfeld in 1880s. these have provided general outline of athenian trireme. sheds ca. 40 m long , 6 m wide. these dimensions corroborated evidence of vitruvius, whereby individual space allotted each rower 2 cubits. doric cubit of 0.49 m, results in overall ship length of under 37 m. height of sheds interior established 4.026 metres, leading estimates height of hull above water surface ca. 2.15 metres. draught relatively shallow, 1 metre, which, in addition relatively flat keel , low weight, allowed beached easily.

construction

the mortise , tenon joint method of hull construction employed in ancient vessels.

construction of trireme differed modern practice. construction of trireme expensive , required around 6000 man-days of labor complete. ancient mediterranean practice build outer hull first, , ribs afterwards. secure , strengthen hull, cables (hypozōmata) employed, fitted in keel , stretched means of windlasses. hence triremes called girded when in commission.

the materials trireme constructed important aspect of design. 3 principal timbers included fir, pine, , cedar. choice in timber depended on construction took place. example, in syria , phoenicia, triereis made of cedar because pine not readily available. pine stronger , more resistant decay, heavy unlike fir used because lightweight. frame , internal structure consist of pine , fir compromise between durability , weight.

another strong type of timber oak; used hulls of triereis withstand force of hauling ashore. other ships have hulls made of pine because come ashore via port or use of anchor. necessary ride triereis onto shores because there no time anchor ship during war , gaining control of enemy shores crucial in advancement of invading army. (petersen) joints of ship required finding wood capable of absorbing water not dried out point no water absorption occur. there gaps between planks of hull when ship new, once submerged planks absorb water , expand forming watertight hull.

problems occur example when shipbuilders use green wood hull; when green timber allowed dry loses moisture causes cracks in wood cause catastrophic damages ship. sailyards , masts preferably made fir because fir trees naturally tall , provided these parts in single piece. making durable rope consisted of using both papyrus , white flax; idea use such materials suggested evidence have originated in egypt. in addition, ropes began being made variety of esparto grass in later third century bc.

the use of lightwoods meant ship carried ashore few 140 men, hull soaked water, adversely affected speed , maneuverability. still faster other warships.

bronze trireme ram

once triremes seaworthy, argued highly decorated with, eyes, nameplates, painted figureheads, , various ornaments . these decorations used both show wealth of patrician , make ship frightening enemy. home port of each trireme signaled wooden statue of deity located above bronze ram on front of ship. in case of athens, since of fleet s triremes paid wealthy citizens, there natural sense of competition among patricians create impressive trireme, both intimidate enemy , attract best oarsmen. of military expenditure, triremes labor- , (in terms of men , money) investment-intensive.

propulsion , capabilities

the ship s primary propulsion came 180 oars (kōpai), arranged in 3 rows, 1 man per oar. evidence provided thucydides, records corinthian oarsmen carried each oar, cushion (hypersion) , oarloop . ship had 2 masts, main (histos megas) , small foremast (histos akateios), square sails, while steering provided 2 steering oars @ stern (one @ port side, 1 starboard).

classical sources indicate trireme capable of sustained speeds of ca. 6 knots @ relatively leisurely pace. there reference xenophon of single day s voyage byzantium heraclea pontica, translates average speed of 7.37 knots. these figures seem corroborated tests conducted reconstructed olympias: maximum speed of 8 knots , steady speed of 4 knots maintained, half crew resting @ time. given imperfect nature of reconstructed ship fact manned totally untrained modern men , women, reasonable suggest ancient triremes, expertly built , navigated trained men, attain higher speeds.

the distance trireme cover in given day depended on weather. on day, oarsmen, rowing 6–8 hours, propel ship between eighty , hundred kilometres. there rare instances when experienced crews , new ships able cover twice distance (thucydides mentions trireme travelling 300 kilometres in 1 day). commanders of triremes had stay aware of condition of men. had keep crews comfortably paced not exhaust them before battle.