The Reconstruction of a Roman Military Troop Transporter from Mainz
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In November 1981, during construction of a new hotel in the immediate proximity to the Rhine in Mainz, wooden remains were found. Archaeologists were informed and recognised straightaway that the remains belonged to a ship. They were able to interrupt further building work for three months, in order to examine the site more closely. During this work they discovered the remains of five ships, which - following dendrochronological analyses - were able to be dated to the late 3rd and especially to the 4th century.
Owing to the short time available for the excavation, the ships were photogrammetrically measured and drawn. Afterwards, they were taken apart and the individual pieces placed in water to prevent them disintegrating. In 1992 these pieces arrived at the Museum for Ancient Shipping of the Römisch-Germanisches Zentralmuseum, where the conservation of the wood, the refitting of the components and the scientific investigation of the wrecks took place.
Immediately following the excavation it was evident that all five ships (Mainz 1, Mainz 2, Mainz 3, Mainz 4 and Mainz 5) because of their shapes, could not have been cargo vessels, but belonged in a military context. Although all ships display individual characteristics, during the examination it could be shown that they belong to two different types. Four of them (Mainz 1, 2, 4, 5) were originally used as troop-transporters, the fifth (Mainz 3) - with a clearly divergent form - may be considered as a patrol-vessel.
The basis for the later reconstruction was given by the wrecks Mainz 1 and Mainz 5, which display very similar constructional features. Ship Mainz 5 was the only ship whose bow section had survived. After sinking, unlike all the others, it had not turned onto one side, so that the ship's bottom was complete; the sides, however, were missing. Unfortunately, the excavation was unable to reveal the whole of the bottom; only the the forepart from the bow to a few frames behind the mast-frame arrived at the museum.
Ship Mainz 1, on the other hand, had turned onto its port side. For this reason, the starboard is missing, apart from the three lowermost strakes, whereas the left side has survived upto the gunwale. Moreover, this ship still has its sternpost.
As like the original wrecks from Mainz the reconstruction is built completely from oak. The 2 cm thick planks are very thin and do not display mortise-and-tenon-joints like Mediterranean ships. On average they are 25 cm wide, displaying partly Z-scarfs. As is usual with Roman ships, the planks are carvel built.
The keel, based on ship Mainz 1, is only 5 cm thick and looks like slightly thickened planks. Like all original keels the keel of the reconstruction displays a channel in the middle, in which the water could collect. Moreover, on their interior sides marked lines could be seen, whereby the Roman shipbuilders marked the positions where the frames were to set later. They lie some 33.5 cm apart. This roughly corresponds to a pes Drusianus, a measurement common in the Gallo-German region during the Roman period. The reconstruction of type Mainz A is based on this measuring unit.
All ships from Mainz were held together by the frames. Ships Mainz 1 and Mainz 5 have tripartite frames: Next to a frame running across the bottom to the chine, the so-called floor-timber, were attached separate side-frames. According to the rhythm of the frames in ship Mainz 1 and 5 the side-frames of the reconstruction are displaced from the sternpost upto the mast-frame behind the floor-timbers; from the mast-frame upto the bow they are attached in front of the floor-timbers. The frames have been worked out of the tree-trunks following the veining and possess a high degree of strength.
At the very thin shipends, the floor-timbers are sawn from branch-forks. Like the originals the frames are some 5 cm thick and between 10 and 15 cm wide. They are connected to the planks with iron nails, whereby the nails are hit from the outside through the plank and frame and their ends bent over.
At its rear end the keel is joined to the sternpost, which upto the gunwales is built from one piece. Parts of it survive on ship 1. A scarf in the sternpost of ship 3 - at the same level as the gunwale - indicats, that the sternpost was build of two seperate parts. The form of this lost part is based on a ship reprensentation of a Roman brick stamp used by the 22nd legion stationed in Mainz.
The stempost of ship Mainz 5 displays a peculiarity which has repercussions for the reconstruction. lt consisted, namely, of only a very short piece and terminated immediately above the water-line. There were no signs that it possessed a scarf at this point. Representations of Roman warships always show above the water-line a prow bent back. The finding of the short stempost on ship Mainz 5 indicates that this ship, too, possessed such a prow-construction. Moreover, since the foremost frame of ship Mainz 5 had survived, the width of the ship at this position was known. lt is not possible to attach the side planks on such a concave stempost; they would have broken.
These observations led to another solution. The whole prow above the water-line was worked as a separate piece. On the short stempost was placed a concave middle stempost, which was attached below to two laterally curved side stemposts. All three pieces diverge upwards, the side stemposts are connected to one another by horizontal beam in the inner side of the ship.
The normal planks of the ship's sides end at the lateral surfaces of the side stemposts. On the front of the side stemposts separate prow planks are attached, which at the same time are set into the middle stempost. The construction is on the one hand light enough, in order to be placed upon the short stempost, but on the other hand also strong and leakproof enough, not to allow the ship to sink.
Unlike Mediterranean ships the Mainz ships had no keelson. Instead they had a mast-frame, which is wider than the usual frames. Characteristic for them is a thickening in the middle with a hole, into which the mast could be set. In the ancient world mast-frames were often placed in ships north ofthe Alps. Besides the measuring unit of the Pes Drusianus the mast frame proves that the Roman shipbuilders, which built the Mainz ships belonged to the provincial population north of the Alps.
Although, then, this type of ship could be sailed, they were in the first instance open rowing ships with one row of oarsmen on each side. This is indicated by the internals and the gunwale. Remains of the thwart stanchions survived in ship Mainz 1 and Mainz 5. They were placed on either side of the keel. This proves that the thwarts did not run from one side to the other, but were interrupted in the middle.
The thwart stanchions were joined to one another by narrow boards, the stringers, which provided stability. In ship Mainz 5 only the lowest stringer has survived. At the same height, narrow internal planks are also to be found on the sides, on which thin transverse beams rest. These support deckplanks right and left parallel to the side-walls beneath the thwarts.
In ship Mainz 1 further details of the internals could be observed. Along the thwart stanchions three stringers in all had been attached. At each of the same heights narrow interal planks are to be found on the sidewalls. All stringers, as well as the second and third internal planks counting from below, display recesses, into which transverse beams must once have been set. lt is striking that the recesses of the second and third levels are set staggered to one another, the recesses of the lower row lie further foreward than those of the upper row.
The remains of the internals in Mainz 1 and Mainz 5 therefore allow to reconstruct the ship's interior completely. The lowest stringers (blue) support a continuous, thin transverse beam, on which deckplanks were placed at the ship's sides. The second and third stringers (yellow) support small, rectangular transverse timbers, which are placed staggered to one another. The reason for this is evident, when one considers the function of the transverse timbers placed here. On nailing a board to these staggered beams, it slants, just as one needs for the foot-rests of the oarsmen. In ship Mainz 1 above this construction a fourth ceiling plank was found (red). The recesses of it are much longer than those of the lower stringers. This plank serves as the outer support for the thwarts, which in the ship's interior, apart from the keel, are held up by the vertical stanchions.
The gunwale bases of ship Mainz 1. It consists of three components: of a fender on the outside, of an inwal on the inside above the scarboard, which strengthens the ship internally and a covering board sitting on the thus broadened shipswall. The covering board consists of a halved tree-trunk. The wood had been partly left semi-circular, partly, however, worked down to a hight of 2 cm. Unworked and worked pieces alternate. In each section there are small, rectangular holes. After refitting the original parts of the ship together, it was apparent that the thicker parts sat between the thwarts, whereas the thinner sections coincided to where the thwarts lay in the ship's interior. Through this arrangement it was clear what the semi-circular sections of this constructional feature meant: they form the support for the oars and the holes take the thole-pins. In the holes of the lower sections between the thole-pins the stanchions of a bulwark are deplaced like it is shown on Roman coins with reperensentations of warships. On the bulwark the soldiers could hung their shields. Simultaneously, the shields provide protection for the oarsmen. Since they would sit high up in the ship, their upper bodies were not protected by the shipswalls.
On the Mainz ships the steering gear is much simpler than on Mediterranean ships. lt consists of a square beam, which runs through the ship at its aft and projects to both sides. Two short, banana-shaped pieces of timber provide support to this beam. One piece is attached directly to the hull. Its rear end is flattened and displays a carpenter's mark. Moreover, at its front end this piece possesses a tenon which fits into a corresponding socket in the rudder beam. Further out the rudder-beam has a second socket, where the second banana-shaped timber was attached.
The gap between the two supporting timbers is too small, however, to push the rudder through.Moreover, the strong rearward support for the rudder indicates that the pressure must have come from the front. For this reason, both side-rudders should be attached in front of the rudder-beam. How they were connected, however, still remains unclear, as traces of an attachment have not survived.
This type of a Roman ship could not only be rowed, but also sailed. Of course, little of that has survived. Apart from the mast-frame there was found in ship Mainz 1 on an interior plank in the aft in front of the rudder beam a small, square recess which could not be connected to the oarsmen or the helmsman. Everything indicates that a beam sat here, to which the ropes for operating the sails were fixed. Moreover, the thwart immediately ahead of this is so near the rudder-beam that the oarsmen sitting here would have hindered the steersman. However, it is sensible in the context of operating the sails, as the men could have immediately heard the commands of the steersman and reacted appropriately. We were reinforced in the reconstruction by many depictions of Roman sailing ships showing that the ropes of the sails run back to the aftship.
Mast, yard and sail have not survived, of course. For the reconstruction one has resorted to ancient representations and chosen the simplest variant each time.
In conclusion, the lines of Mainz 5 and the shape of Mainz 1 suggest that ships of this type measure between 17 and 21 metres long. Their maximum height was 90 cm, their width at midship was a little over 2.5 metres. According to the length the crew comprised 27 to 35 men. Apart from the steersman and two men operating the sails, there were between 24 and 32 oarsmen - 12 resp. 16 in a row. Since this very graceful, exceptionally narrow ship cannot have been a cargo-vessel, and even did not provide room for rowers and a detachment of soldiers, the soldiers must have rowed themselves.
If one considers the function of these ships, the use as troop transporters offers itself. After A.D. 260 the Rhine formed the border between the Roman Empire and the Germania Magna. The Romans built small forts on the eastern bank of the Rhine at dangerous routes of incursion, mostly the valleys of east-bank tributaries. These could only be supplied by ship. This applied not only to provisions and equipment, but also for the troops on guard. In most cases these small forts had surrounding walls which also ran into the river, so that they formed a small harbour.
The type of ship presented here was probably rowed by these troops to their garrisons, in order to take up their guard-duties, until the next ship came to relieve them.
Translated by: Clive Bridger