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Engineering in the Ancient World Reconstructing the Trireme Stephen Ressler, P.E., Ph.D. Professor Emeritus U.S. Military Academy at West Point The Trireme } A oared warship used throughout the eastern Mediterranean from 700 BC onward } } Rowed by 170 men on three levels Employed primarily as a human-powered torpedo Why is it worth knowing about? } Instrumental in: } } } } } Persian suppression of the Ionian revolt Greek victory in the Persian Wars Establishment of the Athenian empire Conduct of the Peloponnesian War Athens’ post-war revival An extraordinarily sophisticated piece of engineering } An intriguing mystery! } The principal means of asserting political power in the eastern Mediterranean The Battle of Salamis (September 480 B.C.) A perfectly optimized balance of speed, maneuverability, and strength Classical Athens 437-432 BC 447-432 BC Historical Development } 3rd Millennium BC: First evidence of primitive multi-oared warships Clay models from Minoan Crete (3000-2700 BC) Historical Development } 2nd Millennium BC: Minoan warships Fresco from Thera (1600 BC) Historical Development } Late 2nd Millennium BC: The Penteconter } } } 50 oars 100 feet long Used as a troop transport The Penteconter Attic black-figure Dinos (c. 550 BC) Historical Development } Around 800 BC: The Bireme Attic bowl, Thebes (c. 735 BC) Double the oarsmen or halve the length? Double the oarsmen or halve the length? Historical Development A first-generation trireme? Assyrian relief showing the evacuation of Tyre, 701 BC The Trireme } } } Probably developed in Phoenicia (and possibly Corinth) around 700 BC Thousands built in Greece, Asia Minor, Egypt, and the Levant Perfected in the Athenian triremes of the 5th century BC Later Oared Warships } Hellenistic Era } } } } Quadrireme, Quniquereme, …, 20er, 30er! Carried large complements of troops and artillery No longer used ramming tactics Roman Era } } Relied on triremes and quadriremes Developed specialized equipment to enhance the ships as platforms for marine infantry The Corvus The Olympias Project (1982-87) } } The Goal: Design, build, and test an accurate working reconstruction of an Athenian trireme from the 5th-century BC The Team: } } } Designed by classics scholars, naval architects, and rowing enthusiasts Funded by the Greek Ministry of Culture, the Hellenic Navy, and private donations Built by a Greek shipbuilder at the Piraeus An extraordinary exercise in experimental archaeology Literary Sources Histories of Herodotus and Thucydides } Oblique references to triremes in Greek poetry, drama, and philosophical treatises } Literary Sources Histories of Herodotus and Thucydides } Oblique references to triremes in Greek poetry, drama, and philosophical treatises } “…and they came to a place where they could see from above a line of light, straight as a column, extending right through the whole heaven and through the earth…; another day's journey brought them to the place, and there, in the midst of the light, they saw the ends of the chains of heaven let down from above: for this light is the belt of heaven, and holds together the circle of the universe, like the hypozomata of a trireme. From these ends is extended the spindle of Necessity, on which all the revolutions turn.” ~ Plato’s Republic Archaeological Sources Wrecks of ancient merchant ships Kyrenia Ship (4th century BC) Archaeological Sources The Athlit Ram (probably 2nd century BC) Archeological Sources Athenian naval inventories } Relief fragments } Vases and vase paintings } Coins } Archaeological Sources Ship sheds at the Piraeus Archaeological Sources Ship sheds at the Piraeus And the Most Important Source… …but only because of global symmetry in time. Key Information } Physical characteristics: } } } } } } } } } } Length and width of hull (122 feet x 19 feet) Shell-first construction Wineglass-shaped cross section Configuration of bow and ram Stern and steering system Number of oars (170 + spares) Length of oars (9 or 9.5 cubits) Spacing between oars (2 cubits) Size and composition of crew Removable mast and sail Key Information } Operating characteristics: } } } } } } Cruising speed (7-8 knots) Turning radius Positive buoyancy Marginally stable Vulnerable to high seas Beached sternfirst at night Design: The Oarsystem Did the ancient Greek trireme have three levels of oars? } Impossibly long oars on the top level } What about quadriremes, quinquerems, and 20ers? Design: The Oarsystem } Well-established alternative naming systems A Scaloccio Alla Sensile Design: The Oarsystem But a three-level oarsystem with all oars of the same length is feasible! Design: The Oarsystem The Lenormant Relief, Athens (410 BC) Askoma Design: The Hull } } } } } } } Accommodate 170 oarsmen at correct spacing Shape consistent with all sculptural and pictorial representations Stern configured for launching and beaching Cross-section and construction methods consistent with all known contemporary vessels Length and width consistent with ship shed dimensions Positively buoyant and stable without ballast Hydrodynamic properties consistent with known cruising speed There is only one solution to this problem Hull Construction: Plank-on-Frame Hull Construction: Shell-First Hull Construction: Shell-First Design: The Hull as Structure } } Sagging Hogging Bending & Shearing Ship’s Weight Buoyant Force The Hull as Structure: Role of the Keel Splices The Hull as Structure: Keel Splices The Hull as Structure: Role of the Hypozoma Design: Other Elements Ram } Decks } Masts & rigging } Sails } Oars } Rowing hardware } Steering oars } The Finished Product } } } Cost: Over $1 million Built with modern tools and a few minor compromises on materials and methods Displacement: } } } 28 tons empty 46 tons manned and fully equipped Power under oar: } } 17 horsepower (sustained) 110 horsepower (in short spurts) 20 hp motor Sea Trials (1987-1994) Sea Trials (1987-1994) Results of Sea Trials Stable under oar and sail } Highly maneuverable } Demonstrated need for a highly trained crew } Speeds almost reached historically attested levels } } } 8+ knots max 6 knots cruising Shortfall could be addressed with a few modest design changes Conclusions A three-level oared warship can achieve historicallyattested levels of performance. } Ancient Greek shipbuilders achieved: } } } } A deep qualitative understanding of nautical engineering Superb shipbuilding skills Modern science and engineering can inform our understanding of history in uniquely powerful ways.