Maritime Archaeology Newsletter From Denmark 21, 2006

Maritime Archaeology

Newsletter No. 21

•

Autumn 2006

from Denmark

Underwater archaeologists at the Zea Harbour Project. Photo: Bjørn Lovén / © ZHP 2005

N0. 21 • AUTUMN 2006

CONTENTS: Continuity and a new beginning . . . . . . . 2 Jørgen Skaarup, Langelands Museum, is retiring . . . . . . . . . . . . . . . . . . . . . . . . . . 4 The management of waterlogged archaeological sites in situ. Research at the conservation department of the National Museum of Denmark . . . . 6 The Zea Harbour Project. . . . . . . . . . . . . 12 Parts of a wooden shipwreck found in the Wadden Sea . . . . . . . . . . . . 16 Conservation of waterlogged wood at the National Museum of Denmark. Recent research and improvements . . . . . 18 An archaeological view at the second Danish-Prussian war . . . . . . . 22 Just published:

ISBN 8785180343 Published by the Viking Ship Museum in Roskilde in collaboration with the National Museum of Denmark DKK 385 / EUR 52 2

Continuity and a new beginning Three years ago the final Maritime Archaeology Newsletter was issued by the Centre for Maritime Archaeology in Roskilde. It summarized the ten years of intensive research activities that the Centre had deployed since its establishment in 1993 on the basis of two five-year grants from the Danish National research Foundation. The general sentiment expressed in that issue, No. 20, was slightly ambiguous to say the least. On the one hand there were pride and gratifying satisfaction. After all, a lot had been accomplished. As intended, the Centre’s activities had brought maritime archaeology on another level, both in Denmark and abroad. A wide range of international publications had been produced. The international peer evaluation report concluded that the ten-year funded period of the Centre had just been what the developing field of maritime archaeology had needed and that it had been ‘money well spent’. Despite pride and satisfaction, however, mournful sadness was not absent from this last Newsletter. There was no denying: with the Centre’s mission accomplished, a very interesting and intensive period came to a close. There was no way that the rules could be changed, however, or that the targeted funding could be extended beyond that point. What future lay ahead for maritime archaeology? Would all initiatives stop? Or would activities continue in slightly altered settings? Would other institutions take up parts of the challenges ahead? How would personal and institutional careers be affected? The fact that the University of Copenhagen had discontinued the position of a lecturer in maritime archaeology and that the National museum had to face serious reductions in its staff did not help to mollify uncertainty and melancholy feelings. Three years later there is every reason

to take stock of developments since. In fact, the Centre’s parent institutions, the National Museum and the Viking Ship Museum in Roskilde, have consolidated a wide range of maritime archaeological efforts and research. The stream of publications is certainly not drying up. The Centre of Maritime and Regional Studies at the University of Southern Denmark and its research school MARINERS/MAST have taken on maritime archaeological research in their cross-disciplinary approaches. PhD projects have been initiated. Mette Busch of the Viking Ship Museum will shortly defend her thesis and Aoife Daly of the National Museum will follow next year. Other institutions, such as the Danish Institute in Athens, host relevant projects. The heritage authority, Kulturarvsstyrelsen, and the regional museums continue to develop policies for archaeological sites in the Danish maritime zones. A regular flow of activities, information, and related research is the result. And last but not least, the University of Southern Denmark has decided to start an internationally oriented master’s course in maritime archaeology this year. Such a curriculum is rare internationally, and in Denmark it can build on the wide Danish experience as well as on the international background of teachers and students. The programme is based in Esbjerg, the maritime industrial city on the Danish North Sea coast. To this background, we decided to revitalize the Maritime Archaeology Newsletter and to jointly introduce the first new issue. Ole Crumlin-Pedersen, started the newsletter in 1993 and has been its editor all through its previous existence. Thijs Maarleveld, has been appointed to lead the new programme in Esbjerg and takes over. Then, it will no longer be the Maritime Archaeology Newsletter from Roskilde. Neither, however, will it be a newsletter from Esbjerg. Even more than before, developments in Danish maritime archaeology depend on a range of participants with complementary roles in heritage, interpretation, research and acade-

mia. Organizationally and geographically they are employed at different places. This should be reflected in the contributions and in the Newsletter’s name. It is meant to serve all maritime archaeological initiatives in Denmark and perhaps as an instrument to loosely bind these together where needed. So from now on, it will be the Maritime Archaeology Newsletter from Denmark. Otherwise, the format remains unchanged. In this first – or rather 21st – issue a new find from the Wadden Sea is introduced by Søren Byskov. Poul Jensen and Kristiane Strætkvern present research that supports the development of conservation techniques at the National Museum’s conservation department. David Gregory reports on issues related to in situ management and monitoring. Otto Uldum stands up for historical archaeology, and Bjørn Lovén guides us through the infrastructure of ancient Piraeus. It is a relatively random collection of subjects illustrating how diverse and interesting the Danish maritime archaeological landscape actually is; a landscape in which it is attractive to take up maritime archaeological subjects or studies. Future issues of the Newsletter will be similarly diverse. With the aspiration to create a binding element, it is the intention to cover as much as possible. Projects and institutions presently not represented are therefore explicitly invited to contribute. In response to current events, we conclude by congratulating Christian Lemée with the presentation of his long-awaited ‘The Renaissance Shipwrecks from Christianshavn’ and Jørgen Skaarup with his retirement. Jørgen’s steady contribution to our field is summarized by Flemming Rieck. This Newsletter is published just before the 11th International Symposium on Boat and Ship Archaeology and other relevant conferences where its international audience meets. We certainly hope that they will appreciate this new beginning of the newsletter, … in appropriate continuity. Thijs J. Maarleveld Ole Crumlin-Pedersen 3

Jørgen Skaarup, Langelands Museum, is retiring In the year 2000, Langelands Museum could celebrate its 100-years anniversary. Today the museum is an institution with a wide scope of activities. Besides its headquarters in Rudkøbing it manages a broad range of special exhibitions at a range of locations on the island of Langeland. It is one of the most active local museums in Denmark, and marine and maritime aspects are high on the agenda of the museum. Despite a history of more than a century it is remarkable that the museum has only had three leaders: its founder Jens Winther, Hakon Berg, and finally Jørgen Skaarup, who has been at the tiller for almost thirty years. After this considerable period, Jørgen has now decided to apply for his pension.

4

Jørgen Skaarup finished his archaeological studies at the University of Copenhagen in 1971 and was promptly employed at Langelands Museum. In 1977, he became its leader. In the period during which Jørgen steered its course, the museum has undergone a remarkable development. The activities of the museum cover a wide spectrum, but in this Newsletter the focus will of course be on maritime archaeology, in which Jørgen and the museum have had a specific significance. The development of Maritime Archaeology in Denmark accelerated after the excavation of the Skuldelev ships in the fjord of Roskilde in 1962. This investigation was carried out by the National Museum, and at the time, no other museums in the country were working with our sunken cultural history. Langelands Museum was the first local museum to take underwater archaeology on the agenda. At an early stage, Jørgen Skaarup realised that many sites, wrecks, and artefacts which today are situated on the seabed can add significant new scientific information to the knowledge of the Fyn-Langeland-region. The museum took the responsibility for underwater archaeology in the entire region, and lately, that area has been enlarged to incorporate the eastern fjords and waters of Sønderjylland. The museum has developed a solid cooperation with sports divers, who act as the ‘local eyes’ under water. Many hours have been spent by Jørgen and the other museum staff in order to educate these local informers. They have learned how to register, record, and excavate under water. The excavations have always been carried out under the responsibility and supervision of professionally educated diving archaeologists. A lot of high quality information has been

added to the archives of the museum and its exhibitions reflect the museum’s underwater archaeological work. Jørgen Skaarup’s commitment to maritime archaeology has been significant. He has been working very hard to encourage other museums in Denmark to engage in underwater work. As a result, the locally funded coverage of Denmark’s water-covered areas is much better than ten years ago. This is not to say that the system is presently foolproof and ideal. One of the weaknesses is that only very few professionals are exclusively employed to dedicate their time to underwater archaeology. Another is that the money for their activities depends on the regions, whereas the significance of underwater heritage often surpasses the regional scale. The most important scientific result of the underwater investigations carried out by Langelands Museum has recently been published in the International Series of BAR, British Archaeological Reports, so that it is available for the international scientific community. Its title is Møllegabet II – A submerged Mesolithic settlement in southern Denmark. Møllegabet is by far the largest excavation under water, which was hitherto carried out by the museum, but it is certainly not the only one. Besides submerged settlement sites, quite a number of wreck-sites can be added to the list of places that have

been investigated under Jørgen Skaarup's leadership. With the retirement of Jørgen one of the strong personalities of Danish maritime archaeology is leaving. He will be missed by his colleagues in Denmark and abroad, but hopefully he will continue to take part in the ever ongoing debate on which direction the management of archaeology should take. In 1987, Jørgen was given the Erik Westerby Award in recognition of his great achievements in the field of archaeological research. He has given a long series of lectures on different archaeological themes both in Denmark and in international gatherings. He has written numerous papers, and his list of published books covers a wide range of archaeological subjects and is certainly impressing: Hesselø-Sølager (tragtbægerkulturens fangstbopladser), 1973. Stengade. Ein langeländischer Wohnplatz mit Hausresten aus der frühneolithischen Zeit. 1975. Stengade II. En langelandsk gravplads med grave fra romersk jernalder og vikingetid. 1976. Flaadet. En tidlig maglemoseboplads på Langeland. 1979. Yngre stenalder på øerne syd for Fyn. 1985. Møllegabet II. A submerged Mesolithic settlement in southern Denmark. 2004. Øhavets middelalderlige borge og voldsteder. 2005. His colleagues in maritime archaeology wish to thank Jørgen for his always inspiring company. Might the future give him fair wind to sail with in his new boat, and hopefully this boat will stop whenever the blue and white flag indicates ongoing underwater activities in the Danish waters. Flemming Rieck

5

The management of waterlogged archaeological sites in situ. Research at the conservation department of the National Museum of Denmark Introduction Denmark is surrounded by water, and even ashore there are many lakes, rivers, and wetlands. All these waterlogged environments have yielded, and will potentially yield many more, archaeological finds. Worldwide, the increase of commercial developments, be they pipelines, cables or wind farms offshore, or road and housing developments on land, has lead to the ever-increasing discovery of new archaeological finds. These finds are often excavated under ‘Rescue’ conditions. In order to set other finds aside for future enjoyment and research, there is a growing trend and need to preserve archaeological finds where they

6

lie, in situ or, alternatively, to redeposit finds in benign environments following their excavation and archaeological documentation (reburial). Since 1996, the National Museum has researched into assessing the feasibility of preserving archaeological sites on land and underwater in situ. The archaeology unit of the National Museum’s conservation department presently has four staff and a full-time PhD student. Two staff-members research exclusively in these two related areas. In order to advise on in situ preservation on a sound scientific basis, the group has concentrated its research in three areas: deterioration mechanisms, methods of monitoring,

and development of protective measures. All three are especially tuned to waterlogged environments in archaeological sites on land and under water. The work of the group will be illustrated with a few case studies. In situ preservation of sites on land Nydam Mose During the Iron Age, Nydam Mose was a small lake into which artefacts were deposited on several occasions between around 200 and 500 AD. The present-day

site is a waterlogged water-meadow and since 1859, several archaeological campaigns have taken place. The last of these was in 1997 when, because of the volume of finds and financial resources needed for conservation, the feasibility of preserving the site in situ was explored. Since 1997, environmental parameters of the site have continuously been monitored in order to discover whether the present conditions of the site are conducive to the future protection of the artefacts. Related to this, a PhD

Left: The find material in Nydam Mose is astonishingly rich. Metals, wood, and leather are all combined in the buried weaponry. Photo: Per Poulsen.

Right: Geotextile covering of Nydam Mose. Photo: Henning Matthiesen.

7

project began in 2003. Its aim is to identify the various micro-organisms causing deterioration of wooden artefacts in the site. By using molecular biological techniques to extract the DNA of bacteria from wood, it tries to identify both the bacteria which have caused deterioration and those which may continue to degrade the artefacts. The project is due for completion in 2007. Growth of the Horsetail (Equisetum) turns out to be another major threat. It has a root system penetrating 1-2 metres into the ground. Unfortunately, these roots penetrate many of the artefacts. Recently, a trial has been conducted, covering an area with geotextile, to see if this can prevent the growth. Much of the initial monitoring work at Nydam concentrated on the areas where past excavations had taken place. As these areas covered approximately 10% of the former iron age lake, geophysical investigations were carried out in 2005 in collaboration with researchers from York University

8

in England, to assess if there were other likely areas of the meadow which contain archaeological finds. Bryggen Bryggen in Norway is one of the oldest medieval trading ports in Europe. It was inscribed on the World Heritage list in 1979. With its traditional timber buildings it used to be one of the Hanseatic League’s four overseas offices. The building structure is actually pre-Hanseatic and dates back to the 11th century. Extensive excavations were carried out between 1955 and 1968 in the northern half of Bryggen after a fierce fire. These excavations were among the first to reveal the huge amount of information that urban deposits contain. The cultural deposits under the protected area are up to 10 metres The wooden foundations of medieval Bryggen under excavation in the 1960's. Photo: Asbjørn Herteig.

thick, covering the entire span of Bryggens history. An extensive monitoring programme was started in 2001 and is currently ongoing. It aims at understanding the settling of the sediments and timber foundations and at mapping the preservation conditions. Åmosen Åmosen is internationally renowned for the large amount of well-preserved prehistoric archaeological finds which lie buried in the area. A range of settlement sites, fishing sites, and ritual deposits were found when peat extraction was carried out during and after the Second World War. Subsequent excavations by the National Museum revealed evidence of logboats, fishing equipment, weapons, houses, shell middens, and a whole host of organic materials such as wood, nut shells, animal bones and antler, fish bones, and insect remains which survived because of the waterlogged conditions. During the 1960's, a large area of Åmosen was drained for agricultural purposes, which unfortunately had a detrimental effect on many of the finds. In 1993, a large area of the site was officially protected and a small lake was created to protect the archaeology. From the mid 1990's, the 'In Situ Group' has been actively monitoring selected areas of Åmosen to assess the preservation conditions. Presently, there are plans to protect a much larger area of Åmosen by establishing a Nature and Culture park. This seeks to increase the waterlevel in the area and prevent further deterioration of the peat which is protecting the rich archaeology. In situ preservation of sites underwater When the Centre for Maritime Archaeology in Roskilde was closed in 2003, research into in situ preservation of archaeological finds in the marine environment has continued at the conservation department. As a matter of course a close collaboration with the Viking Ship Museum has been developed, whereas collaboration with other museums with responsibility for marine archaeology is

developing. The main themes of research in recent years have been to identify the mechanisms of degradation of wood, to develop non-destructive methods to assess the state of preservation of exposed archaeological wood both in situ and in the laboratory, and to develop methods to monitor the environmental parameters within sediments around shipwrecks. Mechanisms of deterioration of wood in the marine environment One of the main threats to submerged wood lying exposed on the seabed is from woodborers like shipworm and gribble. In order to assess the threats of these organisms to exposed finds, maps of salinity, temperature, and dissolved oxygen are being prepared from data collected by the Danish Environmental Agency. Using GIS, these can be overlain with the positions of known archaeological sites. Through an understanding of the ecological requirements of the wood boring organisms, ‘Hot Spots’ of where they are likely to thrive have been identified. In this manner, it is possible to identify areas in which wrecks and other structures are especially under the threat of such deterioration. Even when wood is buried in sediments, it will still undergo deterioration, albeit at a very slow rate. This is caused by the action of micro-organisms such as fungi and bacteria. Interestingly, the main bacteria causing deterioration of wood in waterlogged environments has not yet been formally identified and it is hoped that the aforementioned PhD project can address questions about degradation of wood buried in marine sediments. In situ measurement of the state of preservation of wood To successfully preserve wood in situ it is desirable to know its state of preservation. It is, for instance, important to know whether archaeological wood is structurally strong enough to be covered with 9

sand to prevent the action of wood boring organisms. Moreover, it is essential to have base line data for comparison over time. Knowing its state of preservation will also enable conservators to assess the optimal conservation process in those cases where it may be decided to raise it. The density of waterlogged wood is a good parameter to assess state of preservation. As more of the wood cell is degraded by micro-organisms, the density will decrease. A project dealing with in situ determination of density of waterlogged wood in marine environments by means of its relative conductivity was started in 2005. Equipment for measuring conductivity in waterlogged wood under water was developed and calibration curves for density of wood as a function of the relative conductivity established. The research on conductivity measurements is very promising, as the resolution of the measurements gives the possibility for determination of density gradients in waterlogged degraded wood. The equipment will be developed further during 2006 and 2007, so

10

the depth of measurement in the wood will be registered and the data logged automatically. Monitoring of the environment in marine sediments Should a site be reburied underwater, it is important to be able to ascertain that the environment around the site is conducive to preservation. As mentioned above, processes of deterioration are much slower in waterlogged environments and in the absence of oxygen. The National Museum has been involved in the European Union financed MoSS project (http://www.nba.fi/ Internat/MoSS/eng/index.html) which partly sought to investigate the stabilisation and monitoring of shipwreck sites. Since that time, the Museum has been involved with another large reburial project in Sweden. The Reburial and Analysis of Archaeological Measuring the state of preservation of archaeological wood in situ. Photo: David Gregory.

The Reburial and Analysis of Archaeological Remains (RAAR) project considers the effects of reburial of the materials from the wreck Fredericus (scuttled 1719) in the harbour of Marstrand. For this purpose a monitoring data-logger is put on the seabed (top) and sediment is sampled from the reburial trench (bottom). Photos: David Gregory. Remains (RAAR) (http://www.svk.com/ reburial/index.htm) project considers the effects of reburial of materials from the wreck Fredericus in Marstrand. In this context, The National Museums’ role has been to develop methods to measure various parameters in the re-burial sediments which will give an indication of the presence of oxygen and to understand whether the on-going processes are predominantly associated with oxic or anoxic conditions. From these results, a ‘worst case’ estimate of future deterioration can be given. In conclusion The above is just a very brief overview of some of the major projects that the National Museum is working on in connection with the management of archaeological sites on land and underwater. More information is available at the National Museum’s home page at: http://www.nationalmuseet. dk/sw8878.asp where our publications are listed along with our contact details. Finally, I cannot fail to remark that it is fantastic not only to see the revival of a Newsletter dealing with Maritime Archaeology in Denmark, but also to have the opportunity to contribute to the first edition! Hopefully this won’t be the last time! Congratulations to the editors, both with the Newsletter and with the new course in Maritime Archaeology at the University of Southern Denmark. David Gregory

11

The Zea Harbour Project Introduction The Maritime Archaeology Newsletter from Denmark is an appropriate platform to present a maritime archaeological project that takes place in the Mediterranean. The project began in 2001. It includes analysis of a specific type of maritime cultural landscape, naval harbours, and it includes extended fieldwork. As such, it can be an excellent platform for students in maritime archaeology as it has clear scientific objectives and a good embedding in heritage management. The project The Zea Harbour Project combines land and underwater archaeological investiga-

12

tions at Zea Harbour in Piraeus, Greece. The project began in 2001 as a cooperative effort between the Ephorate of Underwater Antiquities, the 26th Ephorate of Prehistoric and Classical Antiquities, and the Danish Institute at Athens. In 2005, the project began to investigate the harbour fortifications in Mounychia (modern Mikrolimano). In June 2006, a survey of selected parts of the fortification walls surrounding Piraeus were initiated. The Carlsberg Foundation is the principal sponsor of the project. Objectives The main objectives are to investigate Piraeus' ancient naval installations and harbour fortifications. Their construction began under the guiding hand of Themistocles just before the outbreak of the first Persian War Battle of Salamis 480 BC, Athenian trireme ramming a Phoenician trireme from the Persian fleet. Yannis Nakas / © ZHP 2006

in 490 BC. In 483/482 BC, Themistocles also convinced the Athenian citizens to finance the construction of 100 triremes. Triremes were the state-of-the-art, fast and manoeuvrable, three-tiered oared warships with a reinforced ram at the bow. Since Herodotus, it is commonly acknowledged that it was these ships that brought the (narrow) victory at Salamis that decisively reversed the fortunes of the Persian invasion of Greece in 480 BC. Effectively, therefore, the triremes led to the Persian defeat in 479 BC. As a direct result of the decision to build these warships, major development of the naval installations in Piraeus most probably took place. The installations in Piraeus were crucial for keeping the navy operational. It was considered essential to store the fast and rather fragile vessels out of the water when not in use. So, it is likely that the developments in Themistocles’ time were already comprehensive. One hundred and fifty years later, in Alexander’s time, Zea was Athens’ most important naval harbour with a capacity for 196 warships manned by some 40,000 men. Zea’s shipsheds covered more than 55,000 m2 (or the same area as eight

During the 4th century BC, 372 shipsheds lined the shores of Piraeus' three major harbours. Yiannis Nakas / © ZHP 2004 football fields) making it one of the largest and most important building complexes of the Classical Period. The naval harbours Mounychia and Kantharos housed 82 and 94 triremes respectively. Shipsheds It was essential to store the naval vessels out of the water and under cover. For this there are two reasons. First, their slender softwood timbers were subject to attack by wood-eating marine worms. These shipworms were a principal problem of all ancient navies; a worm infested ship required major repairs before it could be made seaworthy again. Second, triremes were kept under a roof because of the effects of sun and rain. Rainwater inside the ship would soak the timbers, swelling them, and allowing fungal decay to attack them. On the other hand, the fierce Mediterranean summer sun would thoroughly dry and shrink the timbers of an uncovered warship, rendering the ship 13

hopelessly leaky and thus unseaworthy. The shipsheds that were designed to store the warships when they were not in operation were enormous. Their main characteristic is a very long ramp facing the waterfront. It was built on a slope to ensure that the ship could come completely clear of the water. The ramp supported the keel of the ship during slipping and hauling operations and is sheltered by an inclined tile roof held aloft by plain limestone columns. Passages on each side of the ramp provided access to the building and working space for the hauling and maintenance crews. Zea The project may concentrate on the classical structure of the site, but Zea has been an active harbour for more than two and a half millennia. Today it is home to a large marina that houses a multitude of yachts and small fishing boats. Cafés line the shore, and the quays bustle with activity day and night, with people parking their cars, eating, jogging, fishing, walking their dogs, and young couples canoodling. These activities 14

When not in use triremes were hauled out of the sea. Yannis Nakas / © ZHP 2006 are reflected in the many modern finds we uncover, and our research also includes the development of the modern harbour and its history. Activities in 2006 Work at Zea began in February; a small team of six archaeologists carried out a five week survey finalizing the documentation of shipsheds excavated in previous seasons. On May 25 during the official visit by Her Majesty Queen Margrethe II of Denmark to Greece, Her Majesty opened the exhibition ‘Science and Art’ at the Danish Institute at Athens. The exhibition presented a wide range of the institute’s activities. As part of this exhibition, the Zea Harbour Project presented the preliminary results of our archaeological research. The presentation consisted of a 3D animated movie clip, posters, a ‘diver’ with full equipment, along with a display of excavated artefacts. The animated movie clip is the first product

of the CHIMERA project, a collaboration between Architecture & Design, Aalborg University, Denmark, and the Zea Harbour Project (the clip can be downloaded from www.zeaharbourproject.dk/News). The aim of the CHIMERA project is to produce realistic 3D models of ancient buildings, which will allow both scientists and the broader public to explore reconstructions of Piraeus’ ancient harbour installations and the ships stationed there in Virtual Reality – thus adding the feeling of ‘space’ in a 1:1 model. Three students from Yale University were trained in our novel surveying techniques. This new project is generously sponsored by Yale Alumnae (the American Friends of the Zea Harbour Project). From mid September until the end of October 2006, the project plan is to continue the excavations of the submerged shipsheds and harbour fortifications at Zea, and new excavations will Archaeologist Stuart Heath inspecting the submerged parts of a shipshed. Photo: Bjørn Lovén / © ZHP 2006

begin on the submerged fortifications in the Mounychia Harbour. The 2006 team will consist of 15 staff members and 9 students. Short term future In 2007, we plan to start an underwater archaeological field school in collaboration with Dr Dimitris Kourkoumelis of the Ephorate of Underwater Antiquities and of Thessaloniki University, Greece. There are many well-established Maritime Archaeology educations, but most of these are theoretically based. We believe that it is very important that the new generations of archaeologists are also taught the practical side of underwater archaeology to a level where they can competently excavate and document antiquities. In 2006, the Zea Harbour Project will train six students in underwater field archaeological methodology during our research excavations, and interested students should contact Bjørn Lovén: [email protected] Project website: www.zeaharbourproject.dk Bjørn Lovén

15

Parts of a wooden shipwreck found in the Wadden Sea On the morning of Monday 24 April 2006, the Fisheries and Maritime Museum in Esbjerg received a call from the Esbjerg based beam trawler, E 4 ”Ho Bugt”. On the night before, the crew had made an unexpected catch in the waters called Knudedyb between the Danish Wadden Sea islands of Mandø and Fanø. In a position just on the fringe of their normal fishing ground, four pieces of wooden wreckage had got stuck in the trawl, and once the crew had pulled the catch aboard they could see that they had The Knudedyb keelson and associated parts at the Fisheries and Maritime Museum, the day after its discovery. The keelson has irregular notches to fit over the floors. The keelson is 37 cm wide and has a preserved length of 405 cm. Its maximum thickness is 27 cm. The (floor) timber is 255 cm long and 21 cm wide. It has a depth of 20 cm. Two planks, with widths of 22 cm and 18 cm and thicknesses of 5.5 cm and 4 cm have also been recovered. Their preserved lengths are 205 and 261 cm respectively. Photo: Thyge Jensen.

come across quite an unusual wreck. Back in the harbour of Esbjerg, curators from the Fisheries and Maritime Museum identified the pieces of wreckage as two planks, one floor and – very interestingly – a keelson, all of which seemingly came from a large vessel of considerable age. Transportation was arranged for the parts to be taken to the Fisheries and Maritime Museum. Here, the parts were documented and provisionally preserved by means of keeping them wet and protected from the sun. After two days, staff from the Preservation Institute in Ølgod collected the wreckage pieces in order to secure a more stable preservation of the parts. Expert opinions as to the type and dating of the vessel parts were obtained from the Viking Ship Museum of Roskilde and from the Maritime Archaeology Department of the University of Southern Denmark. Everyone agreed that there was a chance of this being the first case of a (late) medieval shipwreck found in the waters belonging to what was once the roadsted of medieval Ribe. It was suggested that the vessel would

have been not less than 18 metres in length, making it a ship of considerable size, taken that it is indeed as old as we hope it is. But obviously, there is a large uncertainty involved in premature characterization of such parts. The first priority, therefore, has been to get a qualified estimate of the dating of the wreckage. Thus, dendrochronology has been called in, and on 29 May, dendrochronologist Aoife Daly of the National Museum in Copenhagen went to Ølgod in order to cut out slices of each of the items for dating. Now, everyone awaits the results of this examination. In any event, there are plenty of reasons for maritime archaeology to look further into the position given by E 4 ”Ho Bugt” in the sea bottom of the Knudedyb, where more secrets of early maritime history of Southwest Jutland perhaps await to be uncovered. An unintrusive survey, an assessment of the site and a decision on its future would be the obvious next steps. Parts of the ship are evidently exposed. Parts have been destroyed, but it is likely that the site can produce important information. Søren Byskov

The dynamic environment of Knudedyb is likely to produce important maritime archaeological information. The present findspot is marked with a circle. Photo: Thyge Jensen. The maststep is 29.5 by 19 cm. It is 8.5 cm deep and has a characteristic cross-notch at the side that is probably its fore-end. Photo: Thyge Jensen

17

Conservation of waterlogged wood at the National Museum of Denmark. Recent research and improvements Background Wooden archaeological objects saturated with water cannot be dried without precautions. Owing to degradation and the presence of water, both the physical and chemical properties of archaeological wood are very different from those of fresh wood. Such objects are extremely vulnerable to dehydration, so the overall challenge is to remove the water without collapse, shrinkage, or warping of the material. Research and development of methods tend to follow the challenges connected to major nds. At the National Museum’s Department of Conservation in Brede, research and development of methods began with the conservation of the Skuldelev ships during the 1960s and 70s and went further ahead with the conservation of the Nydam nd. Freeze-drying was then selected as the Left. Surface of a dried out log boat, longitudinal and transversal cracks due to shrinkage and collapse. Right. A cross section of the same log boat showing a well preserved core and a heavily degraded surface. The logboat (1030 BC) was excavated in Varpelev near Køge in 1973. Photo: National Museum.

18

preferred dehydration method. Recent research at the department has primarily been concerned with materials and processes in order to optimize the freeze-drying process, both with respect to quality and costs. Individual steps of the conservation process have been the main focus: analysis of the waterlogged material, impregnation, freezing, and freeze-drying. The outcome of this research is currently applied in the conservation of the large finds from Nydam and from Roskilde Harbour. Challenges connected to the Nydam find Over a period of 5 years, 30,000 pieces of heavily degraded ship timbers and oars, arrows, bows, knives, utensils, and other artefacts were excavated in the Nydam bog. They were deposited between 300 and 500 AD. Most of the artefacts consist of waterlogged wood, several are metal, and a few hundred are composites of metal and wood. In connection with the conservation of the Skuldelev ships, the conservators in Brede had installed equipment for freeze-drying waterlogged wood from tertiary butanol (TBA) and polyethylene glycol (PEG). Due to health hazards, however, this method was

abandoned, and since the beginning of the 1990s freeze-drying after pre-impregnation with aqueous PEG-solutions has been chosen instead. The switch from TBA/PEG to water/PEG was complicated by the fact that the freezedrying plant was not designed to operate at such low temperatures as to ensure the solidi cation of an aqueous PEG-solution absorbed in wood. Nevertheless, the rst hesitant attempts gave acceptable results. Moreover, the capacity of the freeze-drying plant was increased enormously as freezedrying water solutions makes optimal use of the equipment. The old freeze-drying plant was supplemented with a smaller research and production plant in 1991, purchased in collaboration with The School of Conservation. Experience with this experimental installation led to the design of a larger unit. It was financed by the VELUX foundation and installed in 1996. Its tank is 8 meters long and 2 meters in diameter. Both plants are fitted with chamber walls that can be cooled to -35°C, making it possible to freeze

the objects in the chamber and ensuring freeze-drying of PEG-impregnated waterlogged materials. In the production plant, between 400 and 600 Nydam artefacts are generally freezedried in one batch. The process typically lasts 4 months. The objects from Nydam belong to the category of heavily, homogeneously degraded objects. Total collapse of the material occurs if the conservation process is unsuccessful. The process therefore requires iron nerves, full control of the process, of the equipment and knowledge of all process parameters, including the impregnation agents, the degraded wood, and the water. Conservation research Analysis of waterlogged wood Most waterlogged wood appears to have an intact surface and shape upon exposure. As soon as water evaporates from the objects, however, deformation of the material will Wooden artefacts from Nydam immediately after completion of the freeze-drying process. Photo: National Museum.

19

start. The type of deformation will depend upon the degree of degradation. A uniformly, heavily degraded material such as the objects from the Nydam site and Stone Age Sites will shrink and collapse totally. A different degradation pattern is frequently seen with large timbers, hard wood species, and less aged waterlogged finds. These objects are degraded at the surface, often to various depths. They have a less degraded core. It is evident that the degree of degradation depends on wood species, the dimension of the object, the environment in which it became waterlogged, and the duration of its burial. Various methods, destructive as well as non-destructive, for the determination of the degree of degradation have been developed, refined and tested. These methods are essential for a well-founded choice of conservation method. Moreover, they are also of great importance for assessing the Longitudinal section of waterlogged ash impregnated with 0.5 g/g PEG 4000 and freezedried. Right a vessel with laminar PEG. Left an empty vessel observed from the inner part showing pits and cracks in the cell wall. (LVSEM 175X). Photo: National Museum

20

possibility for in situ preservation, as is explained by David Gregory elsewhere in this Newsletter. Freezing of aqueous PEG-solutions A key-parameter for a successful freeze-drying process is that both water and PEG are solid during the process. Therefore, research on the temperatures at which aqueous PEGsolutions melt and solidify has been conducted. The figure below shows an example of the analysis of PEG-structures and distribution of PEG in freeze-dried wood with the aid of a low vacuum scanning electron microscope (LV-SEM). Such observations were complemented with more fundamental research in order to determine maximum temperatures for safe freeze-drying; that is to say the maximum temperatures at which both PEG and water are solid. To this end phase diagrams were developed, including a standard curve for collapse temperatures of aqueous PEG-solutions as a function of the molecular weight. Several methods were employed. One method is based on collecting data on freezing and thawing temperature of aqueous solutions in metal thermos flasks by means of data-loggers. Another method is based

Comparison of experimental data and data produced by simulating the freeze-drying processed by the computerized model for vacuum freeze-drying. on logging the interrelated temperature and strength properties of several solutions in the process of thawing. The freeze-drying process In relation to the freeze-drying process itself, a computerized mathematical model describing heat and mass transfer has been developed. The model is based on the physical principles related to heat and mass transfer both in the vacuum freeze-drying chamber and in porous waterlogged materials. The model is used to produce simulations of freeze-drying processes. These prove to be in close agreement with experimental data and can, therefore, be used to guide a freeze-drying process in relationship to temperature, pressure, wood density, PEGcontent, thickness, and width. In 2005, the three freeze-drying plants at the workshop in Brede have been equipped with temperature sensors connected to data loggers. This became useful to the background of our understanding of the collapse temperatures of various impregnation agents in aqueous solution. When starting the freeze-drying process, the conserva-

tors place 3 to 5 sensors in representative objects. The internal temperature can thus be monitored. During the freeze-drying process, it should never exceed the relevant collapse temperature. Adjustments can be made by regulating the temperature of the chamber wall. This fine-tuning ensures a better result and a reduction in process time and therefore costs. Other issues Of course there are other issues to be addressed by the laboratory's research. Not all objects are suited for PEG treatment and freeze drying. Composite artefacts can include metals to which PEG is corrosive. Freeze-dried objects lack flexibility, which can be a problem when ship-component need to be reassembled. Ropes and fibre artefacts should not com out of conservation looking greasy and dark. All such problems are addressed and backed up by research. Perhaps we should report on this in a future issue of the Newsletter. Research continoue vigorously, and the more so now that the department, School of Conservation, the Viborg County Conservation Laboratory have jointly been enabled to install a new research freeze-drying plant this spring. Poul Jensen Kristiane Strætkvern

21

An archaeological view at the second Danish-Prussian war The war between Denmark and Prussia in 1864 put an end to the Danish Crown’s supremacy over the duchies in the southern part of the Jutland peninsula. About two fifths of the former area of the Danish State was lost to the Prussians, and the new border was drawn south of Kolding. The mighty German confederation had a modern army, and it was soon clear that the Danes would not hold their lines at the Danevirke fortifications. The war was a total disaster for the Danes. It is true that the Danish Navy was able to dominate the surrounding waters, but to no avail because of the German superiority on land. The major task for the fleets in the Baltic and in the North Sea was to block the German harbours – in which they succeeded – but a less spectacular branch of the navy plied the sounds and firths of the inner Danish waters. The flotilla of oared open vessels were stationed in pairs along the south-eastern part of Jutland and around the island of Als. They served as mobile ordnance, intended just as much as firepower against enemy troops on land, as against enemy ships – of which there were few. The task was also to undertake reconnaissance on both sea and land. This role was actually very different from the more prominent role the gunboats played in the war against England after the defeat in 1801 and the subsequent confiscation of the Danish fleet in 1807. The continued ‘Gunboat War’ that went on until 1814 saw the construction of more than 200 gunboats of mainly two sizes; the larger ‘kanonchalup’ (gun sloop) and the smaller ‘kanonjolle’ (gun barge). These were put in action against smaller men-of-war and merchantmen at times when the wind suddenly failed, often with some success. 22

The gunboats of the 1864 flotilla were constructed by the navy master shipwright Andreas Schifter. In the 1820s, a committee had been formed to address the issues raised by the experiences gained in the ‘Gunboat War’. Its central advise was to design a new sloop with improved capabilities with regards to propulsion by sail as well as oars. It should also be able to carry a new kind of gun, widely known as the Paixhans gun after its French inventor. This gun would fire a grenade rather than a solid ball, and tests had shown this to be effective against wooden constructions, such as hulls. The advantage of firing incendiary projectiles from a low firing gun instead of a mortar was tremendous, especially in combat at sea. The grenade (or ‘bomb’ as it was called) would ignite when fired from the gun. A tube-shaped fuse provided for a delay, so that it exploded when it hit the target. The new sloop was equipped with one 60-pound Paixhans gun firing forward. It was mounted in a carriage that ran on rails. In this way, the heavy gun could be stowed low in the central part of the hull in dayto-day routine, whereas it could easily be hauled to the bow in preparation for action. The boat was also armed with a 24-pound swivelling gun aft and four 4-pound howitzers. It was manned by a crew of 64 pulling the 30 oars in pairs. The rigging consisted of two masts with lugsails and a small mizzen. Top right: Frauke Witte of Haderslev Museum assists in the on-site operations in June 2006. Photo: Langelands Museum. Bottom right: Finds in situ, such as a copper nail and a lead bullet cast for navy pillor breech rifle M 1849. Photo: Langelands Museum.

23

With an overall length of slightly over 65 Danish feet (20.5 m) and a beam of nearly 15 feet, it was no dinghy. Well described as it is, it would nevertheless be very interesting to have a chance to look at an actual specimen of such a sloop. Thanks to the perseverance of an enthusiastic diver of the island of Als it is now possible to do so in Sandvig Bay. That sloop is known to be the ‘Bombekanonchalup 19’. The scuttling and deliberate sinking by its crew is well described in the Navy records, as well as in preserved eye-witness accounts of the events of 29 June 1864. After the sinking, the location of one of the guns was clearly visible from a small pier, since it was lying at a depth of only 2.5 m. This was salvaged in the 1890's, still loaded with 20 shot of appr. 6 cm. Presumably, this makes it the 24-pounder, since the Paixhans gun would be loaded with a ball grenade. One of the four small howitzers mounted on the gunwale was also salvaged along with some other objects, such as a length of chain and a copper kettle. No. 19 was originally stationed further south, at the northern entrance to the Als Sound. It had instructions to perform reconnaissance at night. When the Prussians installed large siege guns on the opposite shore, it moved to the inner part of Sandvig Bay, where its field of operation became very limited. The commanding officer was the 36-year-old Hans Peter Edvard Marcher, lieutenant of the reserve (or ‘monthlies’ as they were called) from Copenhagen. He took a bold decision by sinking his ship because he hadn’t received any orders to do so, but gained recognition for it. Not far from Sandvig the gun barge ‘Baagøe’ was stationed at Hardeshøj, under the command of Lieutenant Peter Carl Petersen. Between 8 and 9 am on 29 June this ship and No. 19 experienced the same fate. Petersen performed the duty to blow up his ship on specific order. The report from Captain Muxol, who commanded the western Baltic squadron on board the schooner 24

‘Falken’ (The Falcon), stated that, ‘The reason for their destruction was that one had no choice. The order for the barge was firm. The sloop would, in order to get out, have to face more than 1½ miles of uninterrupted artillery fire from the enemy’s batteries, which must be seen as unforgivable purposelessness. It was not possible to save more of the inventory.’ 29 June was the day the Prussians invaded the island of Als, crossing Als Sound from the Jutland coast. During the night, they started to go across the narrow part, where No. 19 had originally been stationed, using numerous small boats. The brand-new Danish armoured steamer ‘Rolf Krake’ was in the neighbourhood. It was armed with four 60-pounders in two turrets and opened fire on the crossing soldiers with shot and grenades, causing severe injury. The crossing was stopped, but ‘Rolf Krake’ had to leave the scene at daybreak because of the German artillery on land. The invasion was completed during the day. The invasion would leave No. 19, No. 21, No. 22, the gun barge ‘Baagøe’, the paddle steamer ‘Hertha’, and the steam gunboat ‘Willemoes’ between enemy fire from two sides. ‘Rolf Krake’ consequently came to the rescue and managed to get most ships out of the Als Sound by tying them to the far side, thus sheltering them from fire. No. 19 and ‘Baagøe’, however, could not be rounded up, and Marcher and Petersen acted as described. When the crew of No. 19 awaited rescue, a despatch reached Marcher, yet ordering him to scuttle his ship. The witness to this also tells us that, ‘Just during the transport on this stretch of road, the gunboat blew up. We had great troubles calming the horses. A mighty column of smoke reached towards the sky, and thick nauseating smoke pushed forward. When it receded a bit, only the pitiful remains of the hull swam on the troubled waves.’ Since 2003, the exact location of hull remains attributed to the ship is known. After having searched the area for some time,

Finn Rasmussen from Als reported the find. Some coherent structures are visible on the seabed, and a few iron objects have been raised, such as a gudgeon and the head of a sledgehammer. It is hoped that large portions of the hull are preserved and that items belonging to the ship can be identified on the site. When it sank, the ship was fully armed and ready. Due to the explosion one must expect a truly dispersed wreck site. Most likely, however, the hull was torn apart

in large bits and hopefully some of this has been weighed down by the amount of iron in the form of ammunition and of course the ordnance itself. In late June, Langelands Museum underAn iron plate attributed to 'bombekanonchalup 19' is lifted on board the Langelands Museum's historical motor yacht Mjølner for documentation. It was put back on site afterwards. Photo: Langelands Museum.

25

takes a preliminary investigation of the site and actually spends the 142nd anniversary of the sinking on site. The task is to survey the site in order to establish its size, to locate the hull remains, and hopefully to dig a trench across one or more of the hull parts. Judging from the eye-witness description, a substantial amount of the hull was floating on the surface immediately after the explosion, leaving the possibility that it sank as a coherent structure. There are no records of the type of charge used (unless it is in the full report in the admiralty) but if it was a single charge made up of the explosives available for the guns, then the sinking might have been caused by blowing one big hole in the hull, as we are dealing with an open structure. This, of course, is still conjectural but may mean that much of the equipment remained in the hull. This would mean better chances of good preservation, and, more importantly, The 'Bombekanonchalup' as rendered in J.H. Schultz. Den Danske Marine, 1814-1848.

26

there would be a great likelihood that they are stowed in their proper place. Evidently, historical particularism dominates the way the site should be addressed. On that basis, the research potential of the site can be excellent. Site and objects can be interpreted to the background of a well-known context, in which the meaning of each item and its position can be explained. This is a particular strength, as is often put forward when arguing the excavation of a named and historically known wreck. A knapsack recovered from a ship that had to be abandoned in a hurry has quite a different meaning than a specimen that has been kept in storage without ever being used. The same more or less applies to the entire gunboat. It gives us a chance to have an archaeological view at the events in 1864 that have been thoroughly researched by the use of other historical sources ever since the last shot was fired. This kind of ‘historical’ archaeology has not been undertaken at any significant scale in Denmark. In this case, it relates to a very

Maritime Archaeology

specific part of the conflict that is consistently cited as the end of Denmark as a multiethnic state. At a time when the country is adapting to a new kind of multi-ethnicity, this opportunity offers some immediate and concrete evidence that might invoke a linkage with this past. The site offers a great potential in terms of public interest. First and foremost, displaying objects from the site offers visitors a very direct link with the events. This is not to mention the wreck itself if it turns out to be well preserved. Addressing that would of course mean going through a process of raising funds for the necessary conservation. That process might actually prove to be different in this case than in relationship to finds from earlier periods. The immediate appeal of warfare and ties with a not too distant past create other possibilities. In a synergetic approach other kinds of resources may be brought to bear. References: Dreyer, V. Kanonbåde og Alsfjord. Nordborg 1989 Schultz, J. H. : Den Danske Marine 18141848 vol. 1, Copenhagen 1950 www.navalhistory.dk Otto Christian Uldum

Newsletter No. 21 • Autumn 2006 from Denmark

ISSN 09087885

EDITORS: Thijs J. Maarleveld & Helle Kildebæk Raun Lay-out: Jens Lorentzen & Ewa Britt Nielsen DTP: Helle Kildebæk Raun

PRINT: Athene Grafisk Aps., Albertslund © Centre for Maritime and Regional Studies and authors 2006

Maritime Archaeology Newsletter from Denmark is a continuation of Maritime Archaeology Newsletter from Roskilde, Denmark and is published twice a year by:

The Maritime Archaeology Programme, University of Southern Denmark at the Centre for Maritime and Regional Studies Niels Bohrs Vej 9 • DK-6700 Esbjerg Tel. +45 6550 4177 • Fax +45 6550 1091 e-mail: [email protected] The Newsletter is supported by: University of Southern Denmark Centre for Maritime and Regional Studies Fiskeri- og Søfartsmuseet The National Museum of Denmark The Danish Institute in Athens Langelands Museum The Viking Ship Museum Ringkøbing Museum

The Esbjerg campus of the University of Southern Denmark where the Maritime Archaeology Programme starts in September 2006. Photo: CMRS