Search Results (20)

Rogue waves are reported to wreck ships and claim lives. The prompt detection of their presence is difficult due to their small footprint and unpredictable emergence. The retrieval of sea surface height via remote sensing techniques provides a viable solution for detecting rogue waves. However, conventional synthetic aperture radar (SAR) techniques are ineffective at retrieving the surface height profile of rogue waves in real time due to nonlinearity between surface height and normalized radar cross-section (NRCS), which is not obvious in the absence of rogue waves. In this work, a cross-track interferometric SAR (XTI-SAR) imaging approach is proposed to detect elusive rogue waves over a wide area, with sea-surface profiles embedding rogue waves simulated using a probability-based model. The performance of the proposed imaging approach is evaluated in terms of errors in the position and height of rogue-wave peaks, the footprint area of rogue waves, and a root-mean-square error (RMSE) of the sea-surface height profile. Different rogue-wave events under different wind speeds are simulated, and the reconstructed height profiles are analyzed to determine the proper ranges of look angle, baseline, and mean-filter size, among other operation variables, in detecting rogue waves. The proposed approach is validated by simulations in detecting a rogue wave at a spatial resolution of 3 m × 3 m and height accuracy of decimeters. Full article

Bengala, a steamer that sank in 1889 near Capo Rizzuto, Italy, was a relatively new vessel for its time, with an unusually short 18-year service life, given that steamers of the period typically operated for 30 to 40 years. Despite its brief history, SS Bengala played a significant role in the development of Italy’s young merchant navy, undergoing multiple ownership changes and serving various Italian shipping companies. Employed mainly along the route to Southeast Asia, it transported Italian migrants overseas and also participated in troop raids during the Italian military expedition to Eritrea in 1887. Despite its historical significance, no iconographic material has yet been found to depict SS Bengala, and archival research conducted in Italy and England has not uncovered any naval plans, photographs, or drawings of the ship. To overcome this gap, the authors employed new technologies and historical information to create a virtual reconstruction. This research combined archival sources with underwater surveys, including a detailed 3D survey by divers and archaeologists. Archival research, including consultation of official documents, provided critical information on the ship’s dimensions, superstructure, rigging, materials, and construction methods. The 3D modelling of the ship’s external hull, based on precise geometric data from the wreck site, offers a first step towards virtual reconstruction. The modelling is grounded in photogrammetric surveying techniques, ensuring high accuracy in the reconstruction process. The model can be used in augmented reality (AR) applications to enhance underwater exploration, allowing divers to visualise the reconstructed ship in its original environment. Additionally, it supports museum exhibits, interactive visualisations, and educational games, making it a valuable resource for engaging the public with maritime history and archaeology. Full article

Side Scan Sonar (SSS) is widely used to search for seabed objects such as ships and wrecked aircraft due to its high-imaging-resolution and large planar scans. SSS requires an automatic real-time target recognition system to enhance search and rescue efficiency. In this paper, a novel target recognition method for SSS images in varied underwater environment, you look only once (YOLO)-slimming, based on convolutional a neural network (CNN) is proposed. The method introduces efficient feature encoders that strengthen the representation of feature maps. Channel-level sparsity regularization in model training is performed to speed up the inference performance. To overcome the scarcity of SSS images, a sonar image simulation method is proposed based on deep style transfer (ST). The performance on the SSS image dataset shows that it can reduce calculations and improves the inference speed with a mean average precision (mAP) of 95.3 and at least 45 frames per second (FPS) on an embedded Graphics Processing Unit (GPU). This proves its feasibility in practical application and has the potential to formulate an image-based real-time underwater target recognition system. Full article

Colombia has hundreds of historical shipwrecks, but systematic research on this topic is scarce, which makes locating wreck sites problematic. Colombia is home to the Caribbean archipelago of San Andres, Old Providence, and Santa Catalina. Its complex environmental conditions make it a “ship trap”. On 2 February 1894, the USS Kearsarge ran aground on Roncador Cay, one of the Archipelago’s islets, and the location of the wreck site remains uncertain. Due to its role in the American Civil War, the Kearsarge is important naval heritage. Based on historical and cartographic records, orthophotographs, Landsat images, and light-detection-and-ranging (LiDAR) data, this study aimed to estimate the location of the wreck site in a Geographic Information System (GIS). Court-martial records, particularly nautical data and astronomical coordinates, were reviewed, including a study from 1894 indicating the wreck’s location on a map without coordinates. Nautical charts were also analyzed to find the Kearsarge wreck symbol. To identify the wreck site’s ordnance, logbooks and information on previous salvage efforts were examined. The analysis of nautical charts revealed a few shipwrecks, but not the Kearsarge. Historical and remote-sensing data were processed in a GIS, along with the most recent nautical chart of Roncador Cay from 2017, to obtain a possible geographical location. This resulted in coordinates, which were used to detect features associated with the USS Kearsarge in the processed data. Although the wreck was not detected, the data helped to estimate the approximate coordinates for where the wreck could be located, quantifying our degree of uncertainty. Full article

Ballast is essential for vessels to lower their centre of gravity, improve stability, and ease their motion during sailing. During the modern period, heavy materials used for ballasting ships were an issue of particular concern for both authorities and ship owners, subjected to increasing control, regulation, and standardisation. These items represent a very common find in wreck sites and deserve special attention, as their characteristics, distribution, and provenance can deliver critical information for assessing where the vessel was ballasted, sailing routes, ship tonnage, and site formation processes. This article is centred on pig iron ingots, introduced in the early 18th century in sailing warships and shortly thereafter in sizeable merchant vessels, a type of ballast which is frequently overlooked in archaeological research. In particular, specimens retrieved from the Chilean Navy armed transport Infatigable (1855) were analysed through macroscopic and physicochemical characterisation using LM, SEM-EDS, WD-XRF, and IGF. The results obtained indicate the ingots were manufactured with cast iron of different quality, suggesting they may have come from different production centres. The investigation resulted in a better understanding of ballasting practices on a South American navy ship in the early post-independence period and provided new data for discussions of off-site and non-nautical technological issues, such as the materials, knowledge, and techniques associated with the production of pig iron in the mid-19th century. Full article

The wreck of the Punic ship exhibited at the Archaeological Park of Lilybaeum (Marsala, Italy) is a unique example in the world. In this paper, the investigation of some metal finds (30 nails and 3 fragments of sheathings) belonging to the wreck of the Punic ship is reported. Portable X-ray fluorescence and Raman spectroscopy allowed us to identify the elements and compounds constituting them and make some deductions about their composition. X-ray diffractometry, polarised optical microscopy and scanning electron microscopy of the collected micro-samples allowed us to explain the degradation that occurred in the underwater environment. Full article

This paper discusses and underlines the importance of investigations on post-medieval shipwrecks, particularly for wrecks where archival documentation is also available, in relation to gaining a better knowledge of tin-glazed tableware produced in Montelupo (Florence, Tuscany). The case of the Mortella II wrecks is interesting in this sense and also shows how an exact dating of the wreck can allow for a revision of the chronologies of the ceramic classes found on board. In the case of the majolica of Montelupo, the revision of the dating of these ceramics with great diffusion (Europe, Americas, Africa) has major repercussions on international archaeological research. This paper presents a preliminary study of the Montelupo tin-glazed tableware found in the 2021 excavation researches conducted on the Mortella II wreck. The interest in the pottery recovered is high, for several reasons: (A) The dating of the wreck to 1527, clarified thanks to the discovery of a written document related to the sinking of the two Genoese “twin” ships off Saint-Florent (Haute-Corse), which are conventionally defined as Mortella II and III. (B) The almost exclusive presence of Montelupo majolica, a ceramic class among the most important between the 16th and 17th centuries, with a very wide dispersal throughout in the Mediterranean and Europe, as well as internationally. (C) The variety of decorations of the majolica of Montelupo documented thus far in the wreck (at least nine) makes this first sample a reference site for the study of this ceramic class in the first quarter of the 16th century, especially for the precise date of closure for the context (1527). Full article

Early November 1597. After an intense combat with four enemy ships, San Giacomo di Galizia (also known as Santiago), a just over 1000-ton galleon, enters the Ribadeo harbour in a terrible state, where it wrecks. This war vessel had been built in Naples in 1590 and sailed the Mediterranean and the Atlantic until it sank. In late November 2011, during an archaeological survey of the dredge area to improve the navigation of the ports in Galicia, a large ship was found and identified as the San Giacomo, which wrecked 414 years prior to its discovery. Several archaeological campaigns permitted a thorough record of the wreck and the recovery of hundreds of objects which this ship carried on its final journey. These artefacts included ceramics, metalwork, and wood, objects which reflected the activities that occurred on board during its short life. Combining an interdisciplinary approach based on artefacts, documents, and chemical analysis, the aim of this paper is to, on the one hand, attempt to reconstruct the sailing itinerary of the ship over its period of use and, on the other, to discuss how these commodities can help to write new narratives about the activities which occurred on board. Full article

This article presents the results of a preliminary archaeological operation carried out in 2021 on the Mortella II wreck. It was designed as a continuation and complement to the excavation of the Mortella III wreck that was performed between 2010 and 2019 and to which it is historically linked: both ships were Genoese merchantmen sailing together, which sank in 1527 in the context of the 7th Italian War between France and Spain. The paper takes up the main outcomes of the lines of research on shipbuilding and artefacts (anchors and artillery). It discusses their characteristics, comparing them to other wrecks of similar Mediterranean origin. In this way, this work seeks to contribute to the knowledge of Mediterranean shipbuilding and the material culture of the Renaissance, which is currently little known. Full article

This article analyses archaeological evidence for jenever (spelled genever in English) in the Dutch Republic during the Age of Sail (1550–1850). Although excessive alcohol consumption among mariners is a stereotype, there has been surprisingly little critical scholarly work on the subject. Genever was used on ships for medicinal purposes during the seventeenth and eighteenth centuries, but no thorough analysis of alcohol consumption broadly in a Dutch (VOC, WIC, Admiralty) maritime context has been done to date. Since the Dutch stored genever in a distinctive bottle, the archaeological record is helpful to examine Dutch ship’s genever consumption. This article theorises that material evidence of genever for personal consumption and as a commodity for export can be used to aid in identifying a shipwreck’s nationality, and that hypothesis is tested through analysis of a sample of European wrecks excavated along the global shipping routes of Dutch commercial and naval sailing vessels. There is a strong correlation between the presence of both case bottles (kelderflessen) and, later in the period, stoneware bottles (jeneverkruiken) with Dutch shipwrecks or maritime archaeology sites and this is strongly suggested to consider for archaeologists faced with a shipwreck of unknown origin. Full article

Following Max Liboiron’s claim that pollution is colonialism, the anti-colonial maritime archaeologist’s role in the Anthropocene might be to reframe research questions, so that focus is directed toward interactions between marine and maritime, and that the colonial ‘resurrectionist’ approach that has dominated nautical archaeology ought to be reconsidered altogether. This normative statement is put to the test with a 4000-year-old waterlogged dugout canoe that was illegally excavated from the Cooper River in South Carolina, USA. Upon retrieval, the affected tribal entities were brought into consultation with archaeologists and conservators to help decide how to proceed with the canoe’s remains. Tribal representatives reached a consensus to preserve the canoe with PEG and display it in a public museum. This procedure follows the resurrectionist model typical of maritime archaeology in the West, now the dominant protocol globally, where the scholar acts as savior by lifting entire wrecks from watery graves and promising to grant them immortality in utopian museum spaces. However, this immortalizing procedure is at odds with some Indigenous values, voiced by tribal representatives, which embrace life cycles and distributed agency. In the end, the desire to preserve the canoe as a perpetual symbol of intertribal unity dominated concerns surrounding the canoe’s own life, spirit, and autonomy, and that plasticizing it would permanently alter its substance and essence. We argue that the object of the canoe has become subservient to its postcolonial symbolism of Indigenous unity, resilience, and resistance. Further, by subscribing to the resurrectionist model of maritime archaeology, the immortalized canoe now bears the irony of colonial metaphor, as an unintended consequence of its preservation. We echo Audre Lorde’s famous sentiment by wondering if an anticolonial maritime archaeology can ever hope to dismantle the master’s boat using the master’s tools. The conclusions reached here have implications for other maritime and museum contexts too, including the highly publicized case of the wrecked 1859–1860 slave ship, Clotilda. Full article

This paper presents a comprehensive overview of current deep-learning methods for automatic object classification of underwater sonar data for shoreline surveillance, concentrating mostly on the classification of vessels from passive sonar data and the identification of objects of interest from active sonar (such as minelike objects, human figures or debris of wrecked ships). Not only is the contribution of this work to provide a systematic description of the state of the art of this field, but also to identify five main ingredients in its current development: the application of deep-learning methods using convolutional layers alone; deep-learning methods that apply biologically inspired feature-extraction filters as a preprocessing step; classification of data from frequency and time–frequency analysis; methods using machine learning to extract features from original signals; and transfer learning methods. This paper also describes some of the most important datasets cited in the literature and discusses data-augmentation techniques. The latter are used for coping with the scarcity of annotated sonar datasets from real maritime missions. Full article

Coral reefs are threatened by climate change, overfishing, and pollution. Artificial reefs may provide havens for corals, both to escape warming surface waters and to assist in the geographic migration of corals to more habitable natural reef conditions of the future. The largest artificial reefs have been generated by nearly 2000 shipwrecks around the world, but the coral diversity on these wrecks is virtually unknown. Ship size and hull material, location relative to natural reef, time since sinking, ocean currents, and water depth may affect coral diversity. As a test of the biodiversity capacity of very large sunken structures relative to surrounding natural reef, we carried out technical diver-based surveys to quantify genus-level coral diversity on 29 warships sunk in Bikini Atoll and Chuuk Lagoon. We also assessed whether ship length, as an index of substrate availability, and water depth, as an indicator of light and temperature, can serve as predictors of coral diversity. We surveyed a total of 9105 scleractinian corals. The total number of genera identified at Bikini was 34, and at Chuuk it was 51, representing 67% and 72% of genera found on natural reefs at Bikini and Chuuk, respectively. Ship length, but not water depth, was positively correlated with relative abundance and richness at the genus level. Our results suggest that very large wrecks can serve as havens for reef-building corals with a broad genetic diversity, expressed at the genus level, commensurate with corals found on neighboring natural reefs. The role of large artificial reefs could include protecting coral biodiversity from warming surface waters. Full article

We present a case study of multi-coil frequency-domain electromagnetic (FD-EMI) prospection of a wooden ship wreckage from the 17th century. The wreckage is buried in a sandbar in the German part of the tidal flat area of the North Sea. Furthermore, the wreckage was excavated in advance and covered again after investigation. This ground truthing background and the position of the wreckage makes it a unique investigation object to test the feasibility of FD-EMI for prospecting wooden archaeological objects in the high conductive sediments of tidal flat areas. Our results reveal the shape and position of the wreckage in terms of conductivity maps. The resulting signal change caused by the wreckage in conductivity is only 10% of the value of the water-saturated sandy background, respectively, making a cautious process necessary, including a precise height correction. The data, furthermore, reveals a sensitivity to the vertical shape of the wreckage and thus sufficient depth sensitivity, but with reduced sensing depth. The study highlights the great potential of EMI for both in situ heritage management and archaeological research in the Wadden Sea. Full article

Underwater heritage and archaeology is, in general, limited to the few who have permission, and the means to actually dive on location and experience the submarine sites. Dry dive technologies such as Augmented Reality (AR) now offer unprecedented opportunity to change this situation. This paper explores the use of AR storytelling with regard to a World War II landing craft at Phalasarna, Greece. Tank Landing Craft A6 (TLC) was sunk by German aircraft while evacuating Allied troops from Crete in 1941. Its remains still lie just off the coast in a few metres of water. This project revolves around the development of a 3D–animation to make the site more accessible to those who cannot dive. By visually reconstructing the dramatic event of the craft’s final moments under German attack before it settled to the seabed, as well as the site’s present condition, visitors can experience and learn more about both the vessel itself and the historical context. The Indirect AR simulation contains two main modes: a dry dive reconstruction of the wreck as it looks today with detailed multimodal explanations based on historical and archaeological research, and an animation sequence that reconstructs the actual German attack on the ship. This article presents detailed descriptions of the site’s historical background, of the vessel and the design challenges involved in the production process of the app itself. Feedback provided by visitors who recently tested the AR simulation on location is also reported here. Full article