Thomas Dhoop

Energetic swell waves, particularly when they coincide with high water levels, can present significant coastal hazards. To better understand and predict these risks, analysis of the sea levels and waves that generate these events and the resulting coastal impacts is essential. Two energetic swell events, neither of which were predicted by modelled flood forecasts, occurred in quick succession in the English Channel. The first event, on 30 January 2021, produced moderate significant wave heights at or just below the 0.25 year return period along the southwest English coast, but combined with significant swell caused overtopping at East Beach in West Bay and at Chesil Beach. The second event, on 1 February 2021, generated the highest wave energy periods measured at many locations along the southern English coastline and, at high water, caused waves to run up over the promenades at Poole Bay and Christchurch Bay and caused overtopping at Hayling Island. Both events are described in detail, and their spatial footprints are mapped through a joint return period analysis using a copula function. It is found that typical joint return period analysis of water level and significant wave height underestimates potential impacts, while a joint consideration of water level and wave power (P) describes the 31 January event better and a joint consideration of water level and energy period (Te) best describes the 1 February event. Therefore, it is recommended that Te and P are adopted for coastal monitoring purposes, and that future studies further explore the use of both parameters for swell monitoring.

This article examines the practices of classifying and naming archaeological artefacts through the lens of ship archaeology. Debates surrounding ‘cogs’ are used as a case study to demonstrate how archaeologists have found creative solutions for these common problems. It is argued that by adopting the fluid concept of shipbuilding traditions, a variety of vessels that differ in size and construction details, but are grounded in the same construction principles can be meaningfully assembled on the condition that these are acknowledged as modern constructs. The latter point also plays a vital role when discussing the use of the neatly defined historic term ‘cog’ to denote a far more messy archaeological assemblage. The author therefore argues that a differentiation must be made between historical and archaeological cogs and proposes ‘cogs of the archaeological definition’ as an alternative.

This paper is the first presentation of the ideas behind, and preliminary findings of ongoing PhD research at the University of Southampton. The main question posed is: How do changes in shipping reconfigure urban structure and social life in 12th to 14th century northern Europe?

The aim of this paper is to illustrate the impact shipping has had on our cities and demonstrate the archaeological potential of shipwrecks to answer bigger questions about our past.

There is no standard approach to Extreme Value analysis within the metocean community and it remains a topic of active research and debate. This technical note describes an update to the method adopted by the CCO, and provides a comparison with the methods the CCO has previously employed.

Access: http://www.channelcoast.org/reports/ under "All Regions", "Technical Notes"

Bimodal sea states can be a significant contributor to coastal flooding events that are sometimes not  forecast.  Furthermore,  little  is  known  about  the  effect  of  bimodal  seas  on  beaches  and coastal structures,  and  swell  is  rarely  considered  explicitly  in  the  design  or assessment  of shoreline management options.

A  spreadsheet  with  a  time  series  of  monthly  occurrence  of  bimodal  seas  is included,  and the Technical Note provides analysis on their spatial distribution, based on spectral data from the wave network of the Regional Coastal Monitoring Programmes of England.

Bimodal  seas  are  most  prevalent  around  Atlantic-facing  coastlines, but  on  occasions  can  be found at all sites, even the most sheltered. Around half of wave conditions exceeding the storm alert threshold (0.25 year return period) are bimodal seas.

Access: http://www.channelcoast.org/ccoresources/bimodalseas/

Results from wave extremes analysis of a ranked sub-set of 3-hourly wave data are compared to the Peaks-Over-Threshold (POT) method using 0.5 hour data samples, to establish any discontinuity in results from a change in method or data sampling. Measurements from 40 directional wave buoy sites around the English coastline were used, spanning a wide variety of wave conditions. The ranked data method was found to be unsuitable for half-hourly data. However, the ranked method correlated closely with results from the POT method. Suitable thresholds for POT ranged from the 90th to 98th percentile. The POT method (95th percentile) adopted by the CCO in 2017 maintains compatibility with the results achieved historically for design of coastal structures and beach re-nourishment.

Access: http://www.channelcoast.org/reports/ under "All Regions", "Technical Notes"

Palaeomagnetic and geochemical measurements were undertaken of a tidal rhythmite sequence extracted from the Eastwoods field in Winchelsea, East Sussex, UK. The analysis produced an environmental proxy for high energy (i.e. storm and surge) events and demonstrated that a multi-scale reconstruction of storminess is possible using a local proxy as a mediator between established environmental and historical datasets. The rhythmite sequence was dated using Palaeomagnetic Secular Variation (PSV) which produced a date range of 1375 – 1475 ± 50 yrs. However, due to certain caveats, the date comes with some uncertainty. Relative elemental data was obtained using the ITRAX corescanner. Two grain size proxies (Zr/Rb and Zr/Ti), a terrigenous input proxy (Fe/Ti) and a marine carbonate input proxy (Ca/Ti) were established to produce a record of high-energy events captured by the rhythmite deposition. The results suggest that the sequence was originally deposited under relatively stable conditions, followed by a high energy event. When deposition recommenced, seven spikes in the examined proxies indicate that the following accumulation happened under more unstable conditions.

A two-week geotechnical survey was carried out from the 20th of April until the 1st of May 2015 in Winchelsea, East Sussex. As part of this project, the ship graffiti located in the parish church of St Thomas the Martyr and the undercroft underneath the ‘Blackfriars Barn’ building were recorded using Reflectance Transformation Imaging (RTI). The works were conducted as part of Thomas Dhoop’s PhD research at the University of Southampton.

In St Thomas' church, eleven possible ship graffiti were identified and recorded. Most likely, a variety of ship types are represented, including ships of the Nordic tradition, cog of the archaeological definition and perhaps carvel ships. If made in the context of Winchelsea’s function as a harbour, the inscriptions making up the collection should probably be dated between sometime after 1291 and ca. 1530. The individual engravings show characteristics that are common to most medieval ship graffiti in England and as a collection they represent a wide variety in the level of detail in which ships can be represented using this medium. It is argued that the inscribing of ships in St Thomas could have been a means of spiritual protection and a devotional practice – the giving of a votive offering in an act of prayer – that, at least in Winchelsea, cut across different communities of practice and social groups. Except for the expected wear, the graffiti on the stone columns in St Thomas church appear in good condition and are under no immediate threat.

In the Blackfriars Barn undercroft, eleven ships were identified and recorded that together constitute one large seascape. The dating is problematic and could be situated between a range as wide as ca. 1300 and the late 18th century. However, if it is accepted that the graffiti was made at a time when Winchelsea could function as a harbour, a date between ca. 1300 and 1530 can be suggested. Also the engravings in the cellar show characteristics that are common to most medieval ship graffiti in England and depict a variety of ships including cogs, Nordic ships and perhaps – if the inscription was made post the 1440s – also carvel ships. The seascape can possibly be interpreted as an occasion of informal remembrance, perhaps of the general maritime activities at a roadstead in the harbour, or the 1350 ‘Battle of Winchelsea’, or more likely, the mustering of a large fleet before setting out for war. It would appear that the graffito, although fragile due to water percolating into the building, is in a relatively stable condition.

A two-week geotechnical survey was carried out from the 20th of April until the 1st of May 2015 in Winchelsea, East Sussex, targeting the ancient port area and St Thomas church. The works were conducted as part of Thomas Dhoop’s PhD research at the University of Southampton.

A number of geophysical anomalies were found in the data from both survey locations at the former waterfront. In particular the pattern in the southern part of Eastwoods, potentially associated with the medieval private waterfront plots, is of archaeological interest. Also the feature in the northeast corner of the strand, possibly the location of a 16th century storehouse, should be considered of archaeological interest. The auger survey revealed the potential for the study of past climatic events at Eastwoods. In light of this, in future work, an attempt will be made to date the peat layer found in one of the cores. Based on those results, a second auger survey to take sleeved cores is a possibility. The survey at St. Thomas church failed to locate the foundations of the missing part of the structure.

This thesis presents a maritime archaeology of the medieval port town of Winchelsea, in East Sussex, United Kingdom. It specifically researches the aspects of seafaring and storminess which are shown to be vital for understanding how the town was structured and how life was lived. The study brings together a variety of sources – many collected during a fieldwork project at the ancient waterfront – which allowed for the production of a narrative about a community whose attitudes towards the sea shifted over time. In the process, a number of theoretical and methodological tools were developed that allow for (medieval) port towns to be studied in new ways, unhindered by any remaining perceived boundaries between the maritime and terrestrial spheres.

The theoretical underpinning that functions as the study’s foundation is a relational approach – the maritime townscape – aided by two theoretical devices – rhythmanalysis and spatial trialectics – that encourage researchers to consider how the dynamisms of everyday life in a port were materialized in the past and how they can be studied and reconstructed by archaeologists. Approaching Winchelsea from the water, materials and places are discussed as they are encountered along the way. The ship archaeological material from the region is synthesized and contextualised within developments in shipbuilding in northwest Europe. This material serves as the basis for a discussion of the types and sizes of ships that would have called at medieval Winchelsea and the organisation and working of the Camber Estuary which functioned as the new town’s roadstead. These findings are subsequently related to New Winchelsea’s waterfront. Taking the results of a geotechnical survey conducted as part of this project as a starting point, the available information about the area is brought together and the first archaeological interpretation of how the waterfront was structured and could have functioned is put forward. Venturing into the town itself, the tools of spatial analysis are used to raise questions about Winchelsea’s seemingly simple grid-like structure and it is argued that the town was laid out with seafaring in mind. Yet, this structure imposed on a population in a top-down manner was to a large extent negotiated by the people’s own attitudes and affordances. One of the most telling indications of these are the remarkable instances of ship graffiti in the town – in St Thomas’ church and Blackfriars Barn undercroft – which were recorded using reflectance transformation imaging (RTI) and analysed. While highlighting the complexities involved in interpreting and finding meaning in ship graffiti, it is nonetheless argued that they demonstrate a multifaceted relationship with the sea. Finally, a local proxy for high-energy events is developed by dating a rhythmite sequence from a core extracted from the silted River Brede using paleomagnetic secular variation (PSV) and subjecting it to geochemical analysis (micro-XRF) using the ITRAX core scanner. This proxy allowed Winchelsea’s history of storminess to be both refined and contextualised within wider developments of medieval climate change.

Working on the series of storm events that led to the destruction of ‘old’ and the founding of ‘new’ Winchelsea, it is proposed that the production of localised well-dated environmental proxies could contribute to solving methodological difficulties with reconciling information about weather events from written records and information about climate from environmental proxies. The localised proxy for high-energy events generated at Winchelsea revealed that weather conditions seemingly worsened in the second half of the thirteenth century, at the eve of the transition from the Medieval Climatic Anomaly (AD 950-1250) to the Little Ice Age (AD 1400-1700), forcing the residents of Old Winchelsea to protect themselves by building sea defences and ultimately requiring them to relocate to a nearby hilltop. Stimulated by the theoretical device of spatial trialectics, the choice of the new site, located c. 1.5 km inland, is interpreted, not only as a way of physically protecting oneself, but also as suggestive of a growing unease towards the sea. The results of the geotechnical survey indicate that the waterfront at the new site needed a certain amount of work to keep it viable as an access point to the water and provides physical evidence for what is suggested in the written sources: it was “perilous at all flowings of the tide”. Yet, the ambition reflected in the town’s layout and the fact that systems were put in place that allowed Winchelsea to continue functioning as a port, hint at a multifaceted relationship with the sea. Encouraged by the theoretical toolkit of rhythmanalysis, it is shown that people’s daily lives in Winchelsea were, to a large extent, lived to the rhythms of the sea: from millennial and centennial storminess down to the yearly sailing season and the daily tidal cycles. Yet, people’s activities emerged with the rhythms of the sea and not as a result of them. The complexity of this relationship is perhaps captured best by the ship graffiti. On the one hand, people found it necessary to engrave ship drawings in stone pillars in St Thomas, perhaps to acquire some form of spiritual protection from the sea, while – at the same or at a different time – also scratching ship drawings in wet plaster in an ostensibly secular undercroft, perhaps commemorating the mustering of a large naval fleet before setting out, and therefore seemingly celebrating the beneficial aspects of living beside the sea.