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Reconstructing the ancient Greek trireme warship
Reconstructing the Ancient Greek trireme warship J. F. Coates Although the trireme played an essential role in the rise of the Greek controversy about its design and construction. There is, therefore, Anglo-Hellenic project to reconstruct a trireme, on the basis of the conduct trials at sea, When complete, the vessel will be a principal Maritime Museum in Athens.
The Greek trireme, or trieres to give it its proper Greek name, is the most interesting and historically important of all the various types of oared ships of the Mediterranean from the mists of antiquity until their demise near the end of the eighteenth century AD. The trieres was the principal warship of the eastern Mediterranean for three centuries from about 600 BC. By 600 AD its design had been forgotten and has been a subject of controversy among scholars and antiquarians ever since. Nowadays oared ships tend to evoke visions of brutally manned, elephantine galleys in which drum and whip kept wretched slaves plying their oars to total exhaustion and worse. A film entitled ‘Ben Hur’ did much to keep this idea alive. In fact, galleys pulled by slaves belong to an era about 2000 years after the great period of ancient Athens and of the trieres. The ships of the two periods and the conditions in them had little in common. The trieres was a lightly built, slender vessel of elegant and extreme design, packed with 170 skilled and highly trained citizen and other hired oarsmen. It was both manoeuvrable and fast, perhaps the fastest humanpowered ship of all time which, in sufficiently skilled hands, was a potent naval weapon for ramming and breaching enemy vessels. It occupies the central position in the history of oared ships and was the instrument of the naval power which made possible
J. F. Coates,
O.B.E., M.A.
Was born in 1922 and educated at Clifton College and The Queen’s College, Oxford. He entered the Royal Corps of Naval Constructors in 1943. After a series of government appointments in the field of shio desian and construction he became Deputy’Direcibr, Ship Design, Ministry of Defence, in 1977, retiring two years later. Endosvour. Now Serbs, Volume II, No. 2, 1927, ~~~~J’,~~Is
94
~td. ~ht0d
in cht
the achievements for which ancient Athens is famous. The reconstruction of a trieres (figures 1 and 2) for the first time in more than two millennia is therefore an important event in the study of technological and naval history. Operating the trieres at sea will shed a new light on a vital aspect of life in the ancient world.
The ancestry the trieres
of
While paddled and oared boats and ships were once commonplace along the coasts of the world, it seems to have been in the eastern Mediterranean that they developed to a singular degree [l], in all probability because there existed in that region the right social and economic conditions, the right climate and weather, as well as a terrain generally not at all conducive to travel by land [2]. Homer, writing between 900 and 800 BC about events three or four centuries earlier, mentions only the use of ships to carry people to colonise or to fight on land. Early oared ships had 20 or 30 oars and a sail. Such ships, of the general type associated with Egypt, appear in a huge carving portraying a battle in the Nile delta c. 1190 BC (figure 3), while representations of others with rams projecting from the bow at the waterline and up-swept stems appear soon after. By the eighth century BC long 50-oared ships, pentecontors, with all their oars on one level, (figure 4) as well as ships with 50 oars on two levels were being painted on pottery. The long, single-level ships may well have made excellent fast transports because to be strong enough in longitudinal bending their hull sections must have been larger than that needed to accommodate only their fifty oarsmen. Their length, with that number of oarsmen, would have made them slow
Britain. to turn,
however.
city states there is still much much interest in a current best available evidence, and exhibit at the new Hellenic
Two-level ships (figure 5) had the advantage of a shorter hull and so being quicker to turn, vital in a ramming battle. The ram may be regarded as bringing about the true warship with the power to catch and sink, or at least incapacitate, all other types of ship and to take on its own on equal terms. The two-level pentecontor was the main warship of city-states for several centuries; though there was a cheaper version, the hemiolia (‘oneand-a-halfer’), popular with ‘pirates. The naval scene in the ancient Mediterranean, as elsewhere, cannot be properly appreciated unless it is understood that piracy was endemic everywhere and at all times. Even Julius Caesar was once caught by pirates. Their activities flourished or died down according to the effectiveness of the countervailing naval forces of the numerous city-states whose interests, however, as well as capabilities, tended to be relatively local. The eighth century BC ushered in a period of growing prosperity and longdistance trade and colonisation: both Phoenicians and Greeks moved into the western Mediterranean. It may therefore be no coincidence that the trieres was apparently invented shortly before 600 BC. It caused a step-change in size of ship, the number of oarsmen, speed and the cost of each ship. Only the richer city-states could afford them but they were soon widely in service. In little more than a hundred years after their introduction the Greeks, led by the Athenians and through the foresight of Themistocles, had defeated the Persian King of Kings, Xerxes, in the crucial and purely naval battle of Salamis, near Athens, fought by a total of nearly a thousand triereis and a quarter of a million men afloat. Xerxes’ immediate abandonment of a vast military expedition against Greece demonstrated his dependence upon supplies by sea and the loss of his command of the sea by that single defeat. Salamis stands today as one of
Figure 1 The trireme
under construction
the earliest and most telling examples of the way sea power works. The trieres was the supreme warship in the eastern Mediterranean for the next two centuries [3] in the course of which Athens was herself to fall in turn largely as a consequence of naval defeats far from her own shores, principally at Syracuse in Sicily and Aegospotami in the Dardanelles. The trieres was the zenith of an evolution lasting 500 years and achieved a performance under oar unequalled before or since. Contemporary representations are however curiously rare: the best known, the Lenormant Relief, is shown in figure 6, a fragment of a side view which can be compared with the profile drawing of the reconstruction in figure 7. The ram as a naval weapon
Historically, the ram has appeared as a weapon of powered warships when two conditions have been satisfied, the first being that a state of competitive propulsive agility could be maintained between fleets, and the second that ships could close with each other
Figure 2
The trireme
under construction
showing
the ram.
without suffering too great a price in casualties and ship damage. In antiquity, oared ships carried them for more than a millennium. They then disappeared for about a thousand years, which included the era of the sailing warship, before returning, but only briefly, with the arrival of fully steampowered battleships. The ram was the primary ship weapon of two-level pentecontors and triereis in the period between about 900 and 300 BC. It was carried by the later Hellenistic and Roman polyremes as well as by the liburnians that followed the polyremes. However, though no doubt used often enough to justify its retention, it seems to have been of secondary importance in those types of ship the main armament of which was the armed troops on board, archers and, later, missile-throwing catapults. In its time the ram could evidently endow ships skilled in its use with a capacity to win against great odds. It was necessary only to breach a ship to cause her to flood, her waterline to rise and her stability to diminish sufficiently to make the oars unworkable and put the ship hors de
viewed
combat. The attacker having dealt that single blow was immediately free to ram other victims in quick succession if fleet and ship tactics were favourable. Capturing ships by boarding was clearly a slower as well as a bloodier process. The fast Greek trieres was the ultimate development of the oared ramming warship and in her evolution other qualities were sacrificed to obtain excellence with the ram. Specialist armed men, carried on board in addition to oarsmen, some of whom were lightly armed, numbered only fourteen, ten heavily armed infantrymen and four archers. They may have been as much to ensure the temporary capture and defence of beachheads for the crew’s frequent and necessary visits ashore as to provide close defence in battle. The determination of the design of the trieres
No sunken wrecks of ancient warships have yet been found in the Mediterranean, though many wrecks of merchant ships - including one long, oared, merchant galley of about 300 BC -
from the stern.
95
have been excavated. Archaeologists working underwater have thus revealed the constructional methods used by the shipwrights of the region from before 1000 BC to after 1000 AD. The reconstruction of the trieres itself has been developed from the literary, epigraphical, and representational evidence about this type of ship. J. S. Morrison [4], L. Casson, and others have over the past fifty years added some crucial pieces of evidence to what had been established previously. The historical requirements to which an authentic reconstruction of a trieres must conform may be summarised as: 1. Overall beam not to exceed 5Sm: to fit into ship sheds in Piraeus, measured when excavated. 2. Overall length not to exceed 38m: to fit ship sheds. 3. One man to work each oar: from an account in literature. 4. Oarsmen to number 170 in total, in three files at three levels on each side of the ship, 31 in the top file, 27 in the middle, and 27 in the bottom file: from naval inventories. 5. Oarsmen to be spaced, tholepin to two Athenian cubits tholepin, (0.888m) apart: from literature. 6. Oars to be 4.0 and 4.2m long, the short oars being at the ends of the ship: naval inventories and literature. 7. The ship to be capable of being pulled 184 sea miles in just over 24 hours under oar alone: from literature. 8. The shape, construction, and timber dimensions to accord with evidence from excavated wrecks, particularly the fourth century BC Punic long ship at Marsala and the fifth century BC merchant ship at Kyrenia, Cyprus. 9. The ship to accord with known representations, principally the Lenormant relief and the Ruvo vase. As it is not possible in a short article to go into the details of, and the interactions between, these historical requirements, suffice it to state here that in designing a workable ship to satisfy all of them it transpired that, as regards the fundamentals of the design - that is, arrangement of oarsmen, weight, displacement volume, shape and strength of hull, stability, and the layout of the ship and internal furniture - the historical requirements were sufficient to determine the design very closely. The elements of the design proved to be so interlocking, often the case with extreme designs of vehicles, as to make any significantly different solution to the problem of the design of the trieres unlikely [.5]. It was found in the course of design 96
Figure 3
Egyptian
warship
c. 1200 BC.
work that the trieres was adequately stable without ballast. Though clearly undesirable in a vessel whose main purpose demanded agility, ballast had been quite generally thought necessary in triereis on account of the superimposed levels of oarsmen. It also happened that the only long ship to be found and excavated on the seabed of the Mediterranean was carrying shingle ballast when she sank. Reexamination of accounts of battles, however, confirmed the statement by a naval architect, A. F. B. Creuze, writing in the seventh edition of the Encyclopaedia Britannica of about 1840, that ‘The vessels spoken of as sunk were evidently merely stove in and waterlogged’. Certainly unballasted ships made of timber would have a mean density less than that of sea water and would not sink when rammed and holed. That they were then available to be captured by the victor must have added to the attractions of ramming warfare. Conversely, the disappearance of the ram at the end of the Roman period may
indicate a tendency for later oared warships to sink or capsize when holed. Lack of ballast in triereis (and in all probability in other types of ancient warship too) considerably reduces the chances of ever finding any remains. How fast was the trieres?
The power that can be generated by men over a period of time falls sharply as the period considered lengthens: the sustainable speeds of oared craft vary in like manner. Rowing races today are won at speeds of about 11% knots (6 m/s) over courses of one or two kilometres. There is no record of the speed of a trieres over short distances but it is known that a trieres once was pulled 184 sea miles non-stop and without help from sails in a little over 24 hours, thus averaging about 7.5 knots for that very long time. Other long journeys by triereis at similar speeds are also recorded. A 50 km race today, the Boston Marathon, is won at an average speed
; !l’ili”“~~lJ”~,:,I’~~‘lli~~““~~“”~~ Figure 4 Single level pentecontor,
reconstructed
from representations
on pottery.
realise that condition a waterline length of over 30m and nearly 200 oarsmen are required. With that length of waterline and at a speed, V, of 9 knots, the Froude Number of the vessel FN = V/a
= 0.27
the value of I$ at which the third crest of the bow waves partly cancels out the stern wave, reducing wave-making resistance. The ancients found the length of hull needed to achieve the greatest speed under oars, but in doing so they undoubtedly met problems of hull strength associated with longitudinal bending. Figure 5
Two-level
pentecontor
reconstructed
from representations
on pottery.
Hull strength, sea-worthiness and ship operation
of 8.3 knots. J. F. Guilmartin [6] gives a curve of speed against distance for the mediaeval galley (figure 8) to which the other speeds and distances just mentioned have been added. It can be seen that the trieres is more than twice as fast as the galley over a long distance. The resistance of the trieres reconstruction as a function of speed can be estimated from the results of model towing experiments already carried out at the National Technical University of Athens (figure 9). The effective power of oarsmen on fixed seats and with sea oars is less easy to find out. Admiral W. L. Rodgers [7] has quoted a figure for oarsmen in US Navy racing cutters as 124W for nearly half an hour. At that rate the 170
Figure 6
The Lenormant
Relief. Acropolis
oarsmen in the trieres would produce 21kW and, by figure 9, propel the ship at 9.2 knots. It will soon be seen whether the trieres will be able to challenge modern eight-oared racing shells over longer distances and possibly over shorter ones also. The trieres was fast because first it was long and slender enough to avoid generating much wave-making resistance, and second because it was so full of oarsmen and light in build that the wetted area of the hull per oarsman was only about 60 per cent of the corresponding figure for a modern eight-oared racing shell. Thus the main component of its resistance to motion through the water, which is frictional, is relatively small per oarsmen. To
Museum,
Athens.
The waterline length of triereis could not have been much less than 33m if 27 and 31 oarsmen were to be accommodated in their various files. Depth of hull could not have been more than 2.4m from considerations first of hull shape, weight, and displacement which determine draft, and second of the physical limit to the slope of the upper oars which determines the maximum freeboard. Such a hull is 14 depths long. It was open, without the structural benefit of a deck to form an upper flange to its flexural section. The rules of Lloyd’s Register for the construction of wooden ships never allowed such proportionately long and shallow ships to be built, even with a deck. In waves of a height likely to swamp them, triereis’ gunwales would have developed tensile stresses rather greater than the maximum allowable in the wood ship structures of the 19th century AD: W. H. White [8], an eminent Victorian naval architect, quotes the equivalent of 4.0 N/mm* for pine whereas about 5.3 N/mm2 could be developed in triereis’ gunwales. This may explain the necessity for an unusual feature in their structure. Greek triereis (and quite possibly others too) had heavy ropes, tightened by twisting, rigged from one end of the hull to the other. Two loops of such ropes about 47 mm. in diameter formed a four-rope tourniquet. Model experiments with 6 mm. diameter linen cord have indicated that the full-scale ropes could together carry a tension of 120 to 150 kN, which, if the ropes were stretched 0.6m. above the flexural neutral axis of the hull (see hypozoma in figure 10) would reduce the maximum expected tensile stress in the gunwale by about 1.2 N/mm2, near to that regarded as acceptable by White. Mediterranean oared ships were never, it seems, expected to operate in rough waters. Certainly it has always been difficult to work oars in steep 97
Figure 7
Trieres
reconstruction
- profile.
--- rrireme
.lJ z
01 0.1
I
0.3
I I
1
3
I IO
I
30
I 100
I
300
I 1000
Distance in nautical mites
Figure 8
Oared ship and boat speeds.
waves of around the same length as a boat: the difficulty must increase with that length because steep waves of greater length are also higher, but the vertical distance through which a seated man can move an oar blade remains roughly constant irrespective of the length of the boat or ship being pulled. It is also a rough rule that oars cannot be worked by sitting oarsmen in boats rolling more than 3” each way relative to the local wave surface. That will apply to the trieres reconstruction (figure 10). In oared sea-boats of latter years oarsmen used to overcome this difficulty in rough water by ‘standing down’, that is by lowering their feet 98
from the foot stretchers to the floor boards of the boat [9]. The price was, of course, a weakened stroke. In twoand three-level ships only the men in the bottom files could possibly stand down and they would be the first to be put out of action by worsening weather. Multi-manning of oars makes it more difficult to cope with rough water: in the later galleys this must have been why the inefficient and exhausting ‘stand-and-sit’ stroke was adopted at a price in performance. When caught by bad weather (and this can arise very suddenly in the Mediterranean), oared ships could do little but run under sail for shelter, and
if there was none where it was sought there can have been no escape from wreck on a lee shore. Xerxes in 480 BC lost half his fleet on the harbourless coast of Thessaly. In 1569 AD a squadron of galleys en route from Genoa to Spain was blown by the mistral to Sardinia and Sicily with heavy loss. Generally, oared ships kept to the coasts. Trade routes were coastwise and at no stage was any military advantage to be gained by the possession of a deep water, heavy weather navy. Fair weather performance was what counted in warships and that meant performance under oars. Warships had therefore to be packed with oarsmen, more than could live continuously on board. In the case of triereis at least, crews had to go ashore several times a day as a rule to eat, sleep, and perform their bodily functions. Little about the implications of operating such ships has survived in records or literature, though they must have largely determined the scope and pace of naval operations as well as the feasible range of sea power when exercised by oared ships. Aims in reconstructing and operating the trieres
In summary the objects of the current Trieres Project are: 1. To resolve the long-standing controversy about the. design and construction of this historically famous type of ship.
5. To draw attention to the maritime and technical skill which was the prerequisite and the foundation for the cultural achievements of ancient Athens, whose legacy in art, philosophy, literature, drama, politics, and social values survives to this day. 6. To form a fitting principal exhibit in the planned new Hellenic Maritime Museum at New Faliron, Athens. The Trieres
Speed
(knots
1
I 02
I 027
Froude
Figure 9 Effective tonnes. Level trim.
horse power
required
2. To discover and measure its formance at sea. 3. To help towards understanding exercise of sea power in Mediterranean in the fifth subsequent centuries BC.
perthe the and
I 04
I 03
to propel a trireme.
number
Displacement
47
4. In view of the archetypal position of the trieres in the later development of polyremes, to use the knowledge gained from this reconstruction as a basis for study and possible reconstruction of Punic and Roman types of warships.
Project
This is a collaborative Anglo-Hellenic project. The building of the ship, now completing, has been funded in Greece by several national authorities and organisations at a total cost of more than f350 000. In Britain, The Trireme Trust (c/o Wolfson College, Cambridge) is responsible for the research, design, development work, advice during building the ship, and for the conduct of performance tests at sea, planned for this year. The Trust relies upon voluntary support to meet the costs of its part of the project which are expected to total about flO0 000. These have included building, as a preliminary, a tenth part of a whole hull to prove the practicality today of the archaic construction and the crowded oar system. It succeeded in proving both before being shipped to Greece to act as an exemplar in building the trieres herself. The next stage of the project will be to learn to operate the ship with her 170 oarsmen and to ascertain her true performance. This year it is planned to man the trieres with Greek and British oarsmen during July and August. In succeeding years the intention is to take her out for a period each summer to carry out a programme of ‘operational research’ to complete the aims of the project.
M.L
References
Casson,L., ‘Ships and Seamanshipin the Ancient World’, Princeton, 1971. Reprinted in paperback1986. [2] Braudel, F., ‘The Mediterranean and the MediterraneanWorld in the Age of Philip II’, Published in English by Collins, 1972. [3] Morrison, J. S., and Coates,J. F., ‘The Athenian Trireme’, Cambridge,1986. [4] Op. cit., Chapter 8. [5] Morrison and Coates,p. 196. [6] Guilmartin, J. F., ‘Gunpowder and Galleys’, Cambridge,1974. [7] Rodgers, W. L., ‘Greek and Roman Naval Warfare’, U S. Naval Institute, 1937. [S] White, W. H., ‘A Manual of Naval Architecture’, John Murray, 5th Ed. 1900. [9] McKee, Eric, ‘Working Boats of Britain’, Conway, 1983. [l]
Lower limlt con approach
to which oar centreseat of oarsman
I
0
I /
I
2
Metres
Figure 10 Trieres midship face of ship roll of 3”.
section to show minimum
vertical
movement
of oars in
99
The Greek trireme, or trieres to give it its proper Greek name, is the most interesting and historically important of all the various types of oared ships of the Mediterranean from the mists of antiquity until their demise near the end of the eighteenth century AD. The trieres was the principal warship of the eastern Mediterranean for three centuries from about 600 BC. By 600 AD its design had been forgotten and has been a subject of controversy among scholars and antiquarians ever since. Nowadays oared ships tend to evoke visions of brutally manned, elephantine galleys in which drum and whip kept wretched slaves plying their oars to total exhaustion and worse. A film entitled ‘Ben Hur’ did much to keep this idea alive. In fact, galleys pulled by slaves belong to an era about 2000 years after the great period of ancient Athens and of the trieres. The ships of the two periods and the conditions in them had little in common. The trieres was a lightly built, slender vessel of elegant and extreme design, packed with 170 skilled and highly trained citizen and other hired oarsmen. It was both manoeuvrable and fast, perhaps the fastest humanpowered ship of all time which, in sufficiently skilled hands, was a potent naval weapon for ramming and breaching enemy vessels. It occupies the central position in the history of oared ships and was the instrument of the naval power which made possible
J. F. Coates,
O.B.E., M.A.
Was born in 1922 and educated at Clifton College and The Queen’s College, Oxford. He entered the Royal Corps of Naval Constructors in 1943. After a series of government appointments in the field of shio desian and construction he became Deputy’Direcibr, Ship Design, Ministry of Defence, in 1977, retiring two years later. Endosvour. Now Serbs, Volume II, No. 2, 1927, ~~~~J’,~~Is
94
~td. ~ht0d
in cht
the achievements for which ancient Athens is famous. The reconstruction of a trieres (figures 1 and 2) for the first time in more than two millennia is therefore an important event in the study of technological and naval history. Operating the trieres at sea will shed a new light on a vital aspect of life in the ancient world.
The ancestry the trieres
of
While paddled and oared boats and ships were once commonplace along the coasts of the world, it seems to have been in the eastern Mediterranean that they developed to a singular degree [l], in all probability because there existed in that region the right social and economic conditions, the right climate and weather, as well as a terrain generally not at all conducive to travel by land [2]. Homer, writing between 900 and 800 BC about events three or four centuries earlier, mentions only the use of ships to carry people to colonise or to fight on land. Early oared ships had 20 or 30 oars and a sail. Such ships, of the general type associated with Egypt, appear in a huge carving portraying a battle in the Nile delta c. 1190 BC (figure 3), while representations of others with rams projecting from the bow at the waterline and up-swept stems appear soon after. By the eighth century BC long 50-oared ships, pentecontors, with all their oars on one level, (figure 4) as well as ships with 50 oars on two levels were being painted on pottery. The long, single-level ships may well have made excellent fast transports because to be strong enough in longitudinal bending their hull sections must have been larger than that needed to accommodate only their fifty oarsmen. Their length, with that number of oarsmen, would have made them slow
Britain. to turn,
however.
city states there is still much much interest in a current best available evidence, and exhibit at the new Hellenic
Two-level ships (figure 5) had the advantage of a shorter hull and so being quicker to turn, vital in a ramming battle. The ram may be regarded as bringing about the true warship with the power to catch and sink, or at least incapacitate, all other types of ship and to take on its own on equal terms. The two-level pentecontor was the main warship of city-states for several centuries; though there was a cheaper version, the hemiolia (‘oneand-a-halfer’), popular with ‘pirates. The naval scene in the ancient Mediterranean, as elsewhere, cannot be properly appreciated unless it is understood that piracy was endemic everywhere and at all times. Even Julius Caesar was once caught by pirates. Their activities flourished or died down according to the effectiveness of the countervailing naval forces of the numerous city-states whose interests, however, as well as capabilities, tended to be relatively local. The eighth century BC ushered in a period of growing prosperity and longdistance trade and colonisation: both Phoenicians and Greeks moved into the western Mediterranean. It may therefore be no coincidence that the trieres was apparently invented shortly before 600 BC. It caused a step-change in size of ship, the number of oarsmen, speed and the cost of each ship. Only the richer city-states could afford them but they were soon widely in service. In little more than a hundred years after their introduction the Greeks, led by the Athenians and through the foresight of Themistocles, had defeated the Persian King of Kings, Xerxes, in the crucial and purely naval battle of Salamis, near Athens, fought by a total of nearly a thousand triereis and a quarter of a million men afloat. Xerxes’ immediate abandonment of a vast military expedition against Greece demonstrated his dependence upon supplies by sea and the loss of his command of the sea by that single defeat. Salamis stands today as one of
Figure 1 The trireme
under construction
the earliest and most telling examples of the way sea power works. The trieres was the supreme warship in the eastern Mediterranean for the next two centuries [3] in the course of which Athens was herself to fall in turn largely as a consequence of naval defeats far from her own shores, principally at Syracuse in Sicily and Aegospotami in the Dardanelles. The trieres was the zenith of an evolution lasting 500 years and achieved a performance under oar unequalled before or since. Contemporary representations are however curiously rare: the best known, the Lenormant Relief, is shown in figure 6, a fragment of a side view which can be compared with the profile drawing of the reconstruction in figure 7. The ram as a naval weapon
Historically, the ram has appeared as a weapon of powered warships when two conditions have been satisfied, the first being that a state of competitive propulsive agility could be maintained between fleets, and the second that ships could close with each other
Figure 2
The trireme
under construction
showing
the ram.
without suffering too great a price in casualties and ship damage. In antiquity, oared ships carried them for more than a millennium. They then disappeared for about a thousand years, which included the era of the sailing warship, before returning, but only briefly, with the arrival of fully steampowered battleships. The ram was the primary ship weapon of two-level pentecontors and triereis in the period between about 900 and 300 BC. It was carried by the later Hellenistic and Roman polyremes as well as by the liburnians that followed the polyremes. However, though no doubt used often enough to justify its retention, it seems to have been of secondary importance in those types of ship the main armament of which was the armed troops on board, archers and, later, missile-throwing catapults. In its time the ram could evidently endow ships skilled in its use with a capacity to win against great odds. It was necessary only to breach a ship to cause her to flood, her waterline to rise and her stability to diminish sufficiently to make the oars unworkable and put the ship hors de
viewed
combat. The attacker having dealt that single blow was immediately free to ram other victims in quick succession if fleet and ship tactics were favourable. Capturing ships by boarding was clearly a slower as well as a bloodier process. The fast Greek trieres was the ultimate development of the oared ramming warship and in her evolution other qualities were sacrificed to obtain excellence with the ram. Specialist armed men, carried on board in addition to oarsmen, some of whom were lightly armed, numbered only fourteen, ten heavily armed infantrymen and four archers. They may have been as much to ensure the temporary capture and defence of beachheads for the crew’s frequent and necessary visits ashore as to provide close defence in battle. The determination of the design of the trieres
No sunken wrecks of ancient warships have yet been found in the Mediterranean, though many wrecks of merchant ships - including one long, oared, merchant galley of about 300 BC -
from the stern.
95
have been excavated. Archaeologists working underwater have thus revealed the constructional methods used by the shipwrights of the region from before 1000 BC to after 1000 AD. The reconstruction of the trieres itself has been developed from the literary, epigraphical, and representational evidence about this type of ship. J. S. Morrison [4], L. Casson, and others have over the past fifty years added some crucial pieces of evidence to what had been established previously. The historical requirements to which an authentic reconstruction of a trieres must conform may be summarised as: 1. Overall beam not to exceed 5Sm: to fit into ship sheds in Piraeus, measured when excavated. 2. Overall length not to exceed 38m: to fit ship sheds. 3. One man to work each oar: from an account in literature. 4. Oarsmen to number 170 in total, in three files at three levels on each side of the ship, 31 in the top file, 27 in the middle, and 27 in the bottom file: from naval inventories. 5. Oarsmen to be spaced, tholepin to two Athenian cubits tholepin, (0.888m) apart: from literature. 6. Oars to be 4.0 and 4.2m long, the short oars being at the ends of the ship: naval inventories and literature. 7. The ship to be capable of being pulled 184 sea miles in just over 24 hours under oar alone: from literature. 8. The shape, construction, and timber dimensions to accord with evidence from excavated wrecks, particularly the fourth century BC Punic long ship at Marsala and the fifth century BC merchant ship at Kyrenia, Cyprus. 9. The ship to accord with known representations, principally the Lenormant relief and the Ruvo vase. As it is not possible in a short article to go into the details of, and the interactions between, these historical requirements, suffice it to state here that in designing a workable ship to satisfy all of them it transpired that, as regards the fundamentals of the design - that is, arrangement of oarsmen, weight, displacement volume, shape and strength of hull, stability, and the layout of the ship and internal furniture - the historical requirements were sufficient to determine the design very closely. The elements of the design proved to be so interlocking, often the case with extreme designs of vehicles, as to make any significantly different solution to the problem of the design of the trieres unlikely [.5]. It was found in the course of design 96
Figure 3
Egyptian
warship
c. 1200 BC.
work that the trieres was adequately stable without ballast. Though clearly undesirable in a vessel whose main purpose demanded agility, ballast had been quite generally thought necessary in triereis on account of the superimposed levels of oarsmen. It also happened that the only long ship to be found and excavated on the seabed of the Mediterranean was carrying shingle ballast when she sank. Reexamination of accounts of battles, however, confirmed the statement by a naval architect, A. F. B. Creuze, writing in the seventh edition of the Encyclopaedia Britannica of about 1840, that ‘The vessels spoken of as sunk were evidently merely stove in and waterlogged’. Certainly unballasted ships made of timber would have a mean density less than that of sea water and would not sink when rammed and holed. That they were then available to be captured by the victor must have added to the attractions of ramming warfare. Conversely, the disappearance of the ram at the end of the Roman period may
indicate a tendency for later oared warships to sink or capsize when holed. Lack of ballast in triereis (and in all probability in other types of ancient warship too) considerably reduces the chances of ever finding any remains. How fast was the trieres?
The power that can be generated by men over a period of time falls sharply as the period considered lengthens: the sustainable speeds of oared craft vary in like manner. Rowing races today are won at speeds of about 11% knots (6 m/s) over courses of one or two kilometres. There is no record of the speed of a trieres over short distances but it is known that a trieres once was pulled 184 sea miles non-stop and without help from sails in a little over 24 hours, thus averaging about 7.5 knots for that very long time. Other long journeys by triereis at similar speeds are also recorded. A 50 km race today, the Boston Marathon, is won at an average speed
; !l’ili”“~~lJ”~,:,I’~~‘lli~~““~~“”~~ Figure 4 Single level pentecontor,
reconstructed
from representations
on pottery.
realise that condition a waterline length of over 30m and nearly 200 oarsmen are required. With that length of waterline and at a speed, V, of 9 knots, the Froude Number of the vessel FN = V/a
= 0.27
the value of I$ at which the third crest of the bow waves partly cancels out the stern wave, reducing wave-making resistance. The ancients found the length of hull needed to achieve the greatest speed under oars, but in doing so they undoubtedly met problems of hull strength associated with longitudinal bending. Figure 5
Two-level
pentecontor
reconstructed
from representations
on pottery.
Hull strength, sea-worthiness and ship operation
of 8.3 knots. J. F. Guilmartin [6] gives a curve of speed against distance for the mediaeval galley (figure 8) to which the other speeds and distances just mentioned have been added. It can be seen that the trieres is more than twice as fast as the galley over a long distance. The resistance of the trieres reconstruction as a function of speed can be estimated from the results of model towing experiments already carried out at the National Technical University of Athens (figure 9). The effective power of oarsmen on fixed seats and with sea oars is less easy to find out. Admiral W. L. Rodgers [7] has quoted a figure for oarsmen in US Navy racing cutters as 124W for nearly half an hour. At that rate the 170
Figure 6
The Lenormant
Relief. Acropolis
oarsmen in the trieres would produce 21kW and, by figure 9, propel the ship at 9.2 knots. It will soon be seen whether the trieres will be able to challenge modern eight-oared racing shells over longer distances and possibly over shorter ones also. The trieres was fast because first it was long and slender enough to avoid generating much wave-making resistance, and second because it was so full of oarsmen and light in build that the wetted area of the hull per oarsman was only about 60 per cent of the corresponding figure for a modern eight-oared racing shell. Thus the main component of its resistance to motion through the water, which is frictional, is relatively small per oarsmen. To
Museum,
Athens.
The waterline length of triereis could not have been much less than 33m if 27 and 31 oarsmen were to be accommodated in their various files. Depth of hull could not have been more than 2.4m from considerations first of hull shape, weight, and displacement which determine draft, and second of the physical limit to the slope of the upper oars which determines the maximum freeboard. Such a hull is 14 depths long. It was open, without the structural benefit of a deck to form an upper flange to its flexural section. The rules of Lloyd’s Register for the construction of wooden ships never allowed such proportionately long and shallow ships to be built, even with a deck. In waves of a height likely to swamp them, triereis’ gunwales would have developed tensile stresses rather greater than the maximum allowable in the wood ship structures of the 19th century AD: W. H. White [8], an eminent Victorian naval architect, quotes the equivalent of 4.0 N/mm* for pine whereas about 5.3 N/mm2 could be developed in triereis’ gunwales. This may explain the necessity for an unusual feature in their structure. Greek triereis (and quite possibly others too) had heavy ropes, tightened by twisting, rigged from one end of the hull to the other. Two loops of such ropes about 47 mm. in diameter formed a four-rope tourniquet. Model experiments with 6 mm. diameter linen cord have indicated that the full-scale ropes could together carry a tension of 120 to 150 kN, which, if the ropes were stretched 0.6m. above the flexural neutral axis of the hull (see hypozoma in figure 10) would reduce the maximum expected tensile stress in the gunwale by about 1.2 N/mm2, near to that regarded as acceptable by White. Mediterranean oared ships were never, it seems, expected to operate in rough waters. Certainly it has always been difficult to work oars in steep 97
Figure 7
Trieres
reconstruction
- profile.
--- rrireme
.lJ z
01 0.1
I
0.3
I I
1
3
I IO
I
30
I 100
I
300
I 1000
Distance in nautical mites
Figure 8
Oared ship and boat speeds.
waves of around the same length as a boat: the difficulty must increase with that length because steep waves of greater length are also higher, but the vertical distance through which a seated man can move an oar blade remains roughly constant irrespective of the length of the boat or ship being pulled. It is also a rough rule that oars cannot be worked by sitting oarsmen in boats rolling more than 3” each way relative to the local wave surface. That will apply to the trieres reconstruction (figure 10). In oared sea-boats of latter years oarsmen used to overcome this difficulty in rough water by ‘standing down’, that is by lowering their feet 98
from the foot stretchers to the floor boards of the boat [9]. The price was, of course, a weakened stroke. In twoand three-level ships only the men in the bottom files could possibly stand down and they would be the first to be put out of action by worsening weather. Multi-manning of oars makes it more difficult to cope with rough water: in the later galleys this must have been why the inefficient and exhausting ‘stand-and-sit’ stroke was adopted at a price in performance. When caught by bad weather (and this can arise very suddenly in the Mediterranean), oared ships could do little but run under sail for shelter, and
if there was none where it was sought there can have been no escape from wreck on a lee shore. Xerxes in 480 BC lost half his fleet on the harbourless coast of Thessaly. In 1569 AD a squadron of galleys en route from Genoa to Spain was blown by the mistral to Sardinia and Sicily with heavy loss. Generally, oared ships kept to the coasts. Trade routes were coastwise and at no stage was any military advantage to be gained by the possession of a deep water, heavy weather navy. Fair weather performance was what counted in warships and that meant performance under oars. Warships had therefore to be packed with oarsmen, more than could live continuously on board. In the case of triereis at least, crews had to go ashore several times a day as a rule to eat, sleep, and perform their bodily functions. Little about the implications of operating such ships has survived in records or literature, though they must have largely determined the scope and pace of naval operations as well as the feasible range of sea power when exercised by oared ships. Aims in reconstructing and operating the trieres
In summary the objects of the current Trieres Project are: 1. To resolve the long-standing controversy about the. design and construction of this historically famous type of ship.
5. To draw attention to the maritime and technical skill which was the prerequisite and the foundation for the cultural achievements of ancient Athens, whose legacy in art, philosophy, literature, drama, politics, and social values survives to this day. 6. To form a fitting principal exhibit in the planned new Hellenic Maritime Museum at New Faliron, Athens. The Trieres
Speed
(knots
1
I 02
I 027
Froude
Figure 9 Effective tonnes. Level trim.
horse power
required
2. To discover and measure its formance at sea. 3. To help towards understanding exercise of sea power in Mediterranean in the fifth subsequent centuries BC.
perthe the and
I 04
I 03
to propel a trireme.
number
Displacement
47
4. In view of the archetypal position of the trieres in the later development of polyremes, to use the knowledge gained from this reconstruction as a basis for study and possible reconstruction of Punic and Roman types of warships.
Project
This is a collaborative Anglo-Hellenic project. The building of the ship, now completing, has been funded in Greece by several national authorities and organisations at a total cost of more than f350 000. In Britain, The Trireme Trust (c/o Wolfson College, Cambridge) is responsible for the research, design, development work, advice during building the ship, and for the conduct of performance tests at sea, planned for this year. The Trust relies upon voluntary support to meet the costs of its part of the project which are expected to total about flO0 000. These have included building, as a preliminary, a tenth part of a whole hull to prove the practicality today of the archaic construction and the crowded oar system. It succeeded in proving both before being shipped to Greece to act as an exemplar in building the trieres herself. The next stage of the project will be to learn to operate the ship with her 170 oarsmen and to ascertain her true performance. This year it is planned to man the trieres with Greek and British oarsmen during July and August. In succeeding years the intention is to take her out for a period each summer to carry out a programme of ‘operational research’ to complete the aims of the project.
M.L
References
Casson,L., ‘Ships and Seamanshipin the Ancient World’, Princeton, 1971. Reprinted in paperback1986. [2] Braudel, F., ‘The Mediterranean and the MediterraneanWorld in the Age of Philip II’, Published in English by Collins, 1972. [3] Morrison, J. S., and Coates,J. F., ‘The Athenian Trireme’, Cambridge,1986. [4] Op. cit., Chapter 8. [5] Morrison and Coates,p. 196. [6] Guilmartin, J. F., ‘Gunpowder and Galleys’, Cambridge,1974. [7] Rodgers, W. L., ‘Greek and Roman Naval Warfare’, U S. Naval Institute, 1937. [S] White, W. H., ‘A Manual of Naval Architecture’, John Murray, 5th Ed. 1900. [9] McKee, Eric, ‘Working Boats of Britain’, Conway, 1983. [l]
Lower limlt con approach
to which oar centreseat of oarsman
I
0
I /
I
2
Metres
Figure 10 Trieres midship face of ship roll of 3”.
section to show minimum
vertical
movement
of oars in
99