Round One

Assessment, Evaluation and Recording - Round One

(Aggregate Levy Sustainability Fund – more on the ALSF)

Project Background, Aims and Objectives

The aim of Wrecks on the Seabed is to provide industry, regulators and contractors with guidance on the archaeological assessment, evaluation and recording of wreck sites.
 
Wrecks on the Seabed is supported by the Aggregate Levy Sustainability Fund, administered by English Heritage.
 
The project has its origins in Wessex Archaeology’s involvement in licence applications for marine aggregate dredging. While methods for identifying actual and potential wreck sites from desk-based and geophysical prospecting data are becoming well established, methodologies for subsequent stages of investigation are less well developed.
 
The project started in July 2002 and continued until March 2004. Fieldwork took place in August-September 2002 (Year I), and in July- September 2003 (Year II).
 
The project adressed three levels of investigation, using both geophysical and diver-based techniques:
  • Field assessment;
  • Non-intrusive evaluation;
  • Rapid in situ recording.
While Year I concentrated on the initial assessment and quick evaluation of wrecksites, Year II focussed on methods of in situ recording.
 
Methodologies were developed on a sample of known (but generally unidentified) wreck sites off the coasts of Hampshire and Sussex, UK. The wrecks included both metal and wooden-hulled vessels, and aircraft. They were selected from an initial list of 44 sites, with the intention of conducting fieldwork on 14 wrecks in Year I and seven wrecks in Year II.
 
The Year I geophysical investigations included sidescan and magnetometer surveys of 17 sites. In Year II, detailed magnetometer, sub-bottom and multibeam surveys of seven sites took place. Diving investigations in Year I included assessment of nine sites, using surface-supplied divers equipped with video, digital still cameras and underwater tracking. In Year II four out of seven wrecksites were dived on. In situ recording took place on three sites.

General Approach

Diving on the Wrecks on the Seabed projectDiving on the Wrecks on the Seabed projectWessex Archaeology uses a staged approach to archaeological investigation in the context of marine development. A scheme of recording levels has been developed to accompany the possible stages of investigation.
 
These stages reach from the initial desk based assessment to complete excavation and publication.
 
The application of the levels does not have to follow the numbered sequence. Each level can be applied individually if necessary. This means that each investigation can be tailored specifically to the decisions being made and resources can be targeted accordingly.
 
The ALSF project "Wrecks on the seabed" aimed at testing level 1b – 2a assessment and evaluation methods in year I and level 3a in situ recording methods in year II.

Geophysical Survey Methodology

A number of different geophysical survey methods were employed on the wreck sites chosen for survey.
 
It was intended to examine the relevance of these survey methods to archaeological evaluation and to optimise system settings and survey parameters.
 
Multibeam sonar was used to gather bathymetric data from the wreck sites for the creation of 3D terrain models and georeferenced 2D images.
 
Magnetometer surveys were conducted to establish the magnetic signature of the sites.
 
Sub bottom profiler surveys served to provide information on the general geological stratigraphy on the sites and to indicate the presence of buried material.

Multibeam Sonar

MultiBeam SonarMultiBeam SonarMultibeam sonar ensonifies a swath of seabed beneath and to either side of the survey vessel, deriving continuous and well- positioned spot heights for many thousands of points on the seabed as the vessel moves forward.
 
From multibeam data, 3D terrain models can readily be created. Depressions and features projecting from the seabed can be displayed and quantified in terms of their dimensions.
 
For the "Wrecks on the seabed" project a Reson SeaBat 8125 multibeam echosounder was used.
 
The survey data was processed by Wessex Archaeology using the IVS Fledermaus visualization system.
 
The results were 3D terrain models, 3D fly through movies and 2D georeferenced images. The 2D images were used as a base for site plans. Divers used prominent features as datum points and carried out range and bearing measurements or used offset and triangulation to map other objects, as can be seen from this plan of the Portland Stone Wreck.

Magnetometer

Marine magnetometers detect variations in the Earth's total magnetic field. These variations may be caused by the presence of ferrous material on or under the seabed, geological features or diurnal variations in the Earth's magnetic field due to solar activity. Marine magnetic surveying has become a standard technique for mapping the location of ferrous material on the seabed.
 
Magnetometers are usually towed behind the survey vessel at a sufficient distance to avoid any magnetic disturbance caused by the survey vessel itself.
 
For the 2003 fieldwork, a Geometrics G-881 caesium vapour magnetometer was deployed on each wrecksite at a linespacing in the order of 10-20m.
 
In the course of post processing the magnetometer data was imported into Fledermaus and overlayed over multibeam data to show the relationship between the anomaly and the visible wreck site.

Sub bottom profiler

Sub bottom profilers work on the same principle as simple echosounders, but use much lower frequency acoustic energy. The acoustic pulses penetrate below the seabed and into the sediment. Returning echoes from sub bottom features such as geological stratas or buried material create a trace on paper and in the digital record.
 
A number of different sub bottom profiling systems are available. These are categorised by the frequency content of transmitted pulses.
 
Low frequency systems, often called boomers achieve high ground penetration at low resolution, while higher frequency systems, called pingers, achieve high resolution but only limited ground penetration.
 
For the 2003 fieldwork, Wessex Archaeology employed an Applied Acoustics boomer plate. The survey sought to determine the geological setting of the wreck sites and to detect pieces of buried wreckage that were not visible in magnetometer, sidescan or multibeam results.
 
The data was processed using Coda software and then interpreted. Typical sub bottom profiler data, acquired from wreck site 5010 can be seen here.

Diving Methodology

The Wessex Archaeology dive team consisted of five team members: archaeological supervisor; diving supervisor; diver; standby diver and tender. All divers held commercial diving qualifications.
 
The diving support vessel EMU Surveyor was hired for all diving fieldwork in the ALSF project "Wrecks on the Seabed". Access to the water was provided by a transom gate and diving ladder at the stern.
 
Surface Supplied Diving Equipment was used throughout the project. The air supply on board consisted of four 300bar 50l J-cylinders.
 
The air supply was controlled with a DIVEX two diver panel with integrated pneumofathometers. An AMRON communication box was used for diver communication.
 
Divers were linked to the surface by umbilicals which included air supply, pneumo tube, communication, light and camera cables. Standard KMB 28 band masks with neoprene hoods were used. Faceplate mountings held video camera and light.
 
Underwater recording was carried out using the hat mounted camera, handheld digital stills camera and by making measured sketches on drafting film. Watch an extract of the footage (opens your media player, MPEG1, 1.3Mb).
 
For each dive the wreck was marked with a buoy, before anchoring the vessel on a two point mooring for the duration of the dive. If longer fieldwork was planned, a shot was secured to a part of the wreck.
 
Due to strong tidal currents in the area, diving was only carried out in slack water periods.

Acoustic Diver Tracking

Throughout the project, diver orientation was enhanced by an acoustic USBL diver tracking system, manufactured by Sonardyne.
 
In this system, range and time difference measurements of sound signals emitted by a beacon attached to the diver on the seabed allow to calculate the divers position.
 
Further details on acoustic theory can be found at: http://www.sonardyne.co.uk/theory.htm#USBL
 
Equipment setup on EMU SurveyorEquipment setup on EMU SurveyorA transceiver assembly mounted over the side of the vessel received the sound signals. A navigation processor calculated and displayed the relative diver position. Further software packages were used to transform the relative coordinates into real world geographical coordinates and to display the diver position overlayed on a georeferenced multibeam or sidescan image of the wreck.
 
As the transceiver and thus the coordinate reference frame was fixed to the vessel and influenced by yaw, pitch and roll, additional equipment such as a motion reference unit and a gyrocompass had to be used to compensate for the boat’s movement and enhance tracking accuracy.
 
The average positioning accuracy achieved with the USBL system ranged from 2m to 6m. This made the system suitable for basic orientation on large wreck sites, but not for surveying or detailed orientation in low visibility conditions. The main factors responsible for inaccuracies were related to boat positioning and boat movement compensation rather than the acoustic tracking system itself.

Surveyed Wrecks

The study area stretched from Hayling Island in Hampshire to Beachy Head in East Sussex. The environmental conditions in this area resemble the conditions that prevail in most of the aggregate dredging areas on the British south coast.
 
In addition to the surveys undertaken in the Year I and Year II campaigns of the project, a number of designated historic wreck sites, protected under the Protection of Wrecks Act 1973 were surveyed with multibeam sonar, magnetometer and sub bottom profiler as a project variation.
 
Click the spots on the map below to explore the wreck sites.

Map showing the study area and clickable spots to locate information about the wrecks Site 5007 Site 5005 Site 5003 Site 5009 Talis Site 5001 Site 5006 Devon Coast Site 5002 B-17 Site 5008 Site 5004 Concha Site 5013 Site 5011 Portland Stone Wreck Site 5031 Site 5010 Site 5043 Mary Rose Invincible HMS A1 Hazardous

HMS A1

HMS A1 was the first submarine which was designed and built in Britain. She was commissioned in 1903, but tragically lost with all hands in a collision off the Nab light in 1904.
 
The submarine was raised in 1904 and then used for training and experimental purposes. HMS A1 finally disappeared during an unmanned exercise, when the tow broke. Despite of extensive searches, the Royal Navy was unable to locate the submarine. The wreck was rediscovered in 1989 and designated as a historic wreck under the Protection of Wrecks Act 1973 in 1998.
 
Wessex Archaeology conducted a magnetometer survey, a sub bottom profiler survey and a multibeam sonar survey on the wreck site in 2003.
 
The results of the multibeam survey can be downloaded in the form of a movie clip (MPEG, 6MB).

Hazardous

A top view of the multibeam data.A top view of the multibeam data.Hazardous was originally built as Le Hazardeux, a French 3rd rate, in Port Louis in 1698. She was captured by the Royal Navy in 1703 and converted to an English 4th rate of 54 guns in Portsmouth.
 
Hazardous was lost in November 1706, when she was run aground in Bracklesham Bay.
 
The wreck was discovered by divers in 1977 and designated as a historic wreck under the Protection of Wrecks Act in 1986.
 
In 2003 Wessex Archaeology carried out magnetometer, sub bottom profiler and multibeam sonar surveys on the site.
 
A short movie clip showing the results of the multibeam survey can be downloaded here (MPEG, 6Mb).

Invincible

Top view of the multibeam data of the Invincible site.Top view of the multibeam data of the Invincible site.The Invincible was a 3rd rate 74 gun ship of the line built in Rochefort in 1744. She was captured by Admiral Anson in the Battle of Finistere in 1747.
 
Due to her superior design she was purchased by the Royal Navy and commissioned as a 3rd rate ship of the line. In addition her lines were taken off, and two new 74 gun ships, the Valiant and the Triumph were built after her design in 1757.
 
In 1758 a jammed rudder caused the ship to run aground on Dean Sand. Despite several efforts the Invincible could not be made free. All guns and the crew were taken off, but the hull remained on Dean Sand.
 
The wreck of the Invincible was discovered in 1979 and designated in 1980.
 
Wessex Archaeology carried out multibeam sonar, magnetometer and sub bottom profiler surveys on the site in 2003.

Mary Rose

Top view of multibeam dataTop view of multibeam dataIn 2003 Wessex Archaeology conducted a multibeam sonar, magnetometer and sub bottom profiler survey on the site of the Mary Rose.
 
Built in 1509, the Mary Rose was on of the bigger warships in Henry VIII fleet. She was rebuilt in 1536 and sank in 1545 during an engagement with the French fleet in the Solent.
 
The site was discovered by Alexander McKee in 1971, designated in 1974, and then excavated and partly raised. The main part of the hull is now being conserved in the Portsmouth Historic Dockyard, but the bow section was not raised during the main excavation and there is high potential for the survival of artefacts and features outside of the excavation area.
 
The Mary Rose site is currently being excavated by the Mary Rose Trust.

Wreck 5001

Site 5001 was surveyed with a sidescan sonar in August 2002. The wreck is said to be the remains of a World War II B-24 Liberator bomber. It is not marked on charts.

Wreck 5002 B17- Bomber

Summary

Wreck 5002, the remains of a Second World War Bomber, lies in 16m deep water SSW of Newhaven. The wreck was first mentioned in 1975, when a SCUBA diver failed to surface after a dive. This accident led to partial dismantling of the wreck by the Royal Navy. In 2002 and 2003 Wessex Archaeology carried out a geophysical and diving assessment of the site to confirm the aircraft type identification and to establish the extent of the site. Like all aircraft lost in military service, the site is protected under the Protection of Military Remains Act 1986.
 
Click the spots below to view underwater photographs and video footage from the dive.

Wreck 5002 MapEngine 1 Wing Structure Engine 2 Engine 3

Results

A close inspection of the aircraft engines on site confirmed the identification of site 5002 as a B-17 bomber. The B-17 was one of the most common daylight bombers during the 2nd World War. It was used by the RAF as well as by the USAF from many British airfields for bombing raids to France and Germany.
 
The first B-17’s (model C) were employed in the European war theatre in 1941. A series of amendments and improvements led to the construction of the B-17 G from 1943. Altogether 8680 B-17’s of this model were built. 1301 of these were either shot down, crashed or were ditched. The B-17 G had a wingspan of 31.6 m, a length of 22.8m and a height of 5.8m. It weighed 22475 kg. The maximum speed was 295 mph at a height of 7625m. The range of the bomber was 1760 km. B-17 G’s were armed with 13 .50 cal machine guns and carried 2724 kg of bombs.
 
Further details on the histoy of the B-17 bomber can be found at http://b17bomber.de/english/index.php.

Engine 1

One of the three 9 cylinder radial air cooled Wright Cyclone GR 1820 engines on site. Two propeller blades are still attached and the variable propeller pitch mechanism is visible.

Engine 2

The second engine, the propeller is missing and the engine block is partly buried.
 
Video footage (with diver audio) of this feature is available (MPEG, 1.3Mb). It will open in your system's default media player.

 

Engine 3

Third engine with propeller attached. The engine block is buried.

Wing Structure

Tubular frame structure, probably part of the internal wing framing.

Wreck 5003

Wreck 5003 was surveyed with sidescan sonar and magnetometer in 2002. The wreck appeared to be 75m long and 15m wide, standing 4.8m proud of the seabed. A significant magnetic anomaly is associated with the wreck.
 
The site was not subject to an archaeological dive survey and the wreck has not been identified.

Wreck 5004 Concha

Summary

Wreck site 5004 is situated SSE of Littlehampton in West Sussex. The wreck lies in 10.7m (CD) of water on a sandy/ gravelly seabed. The wreck was discovered by the UKHO in 1975 at a depth of 18m. In 1984 the site was dived for the UKHO and described as a big metal wreck with iron propeller and a cargo of iron ore.
 
Wessex Archaeology conducted a geophysical survey on the site in 2002 and 2003 and carried out documentary research.
 

Results

Using documentary sources and measurements taken off the multibeam data, wreck 5004 could be identified as the Belgian steamer Concha.
 
The Concha was en route from Carloforte in Sardinia to Antwerp with a cargo of iron, copper and tin ore, when she collided with the steamer Saint Filians from Liverpool on the 20th August 1897. Nine sailors died in the accident. The expensive cargo of tin and copper ore was probably salvaged after the accident, while the iron ore remained in the wreck.
 
(Lloyds Register 1896)(Lloyds Register 1896)

Wreck 5005

Wreck 5005 is known as the 'Gun Wreck', but may be the remains of the Umba, a Rostock built merchant vessel, which was taken as a prize by the British in World War I, and torpedoed by a German submarine in 1918.
 
The wreck was surveyed with sidescan and magnetometer in 2002. The sidescan data shows a large wreck (96m x 13m) which appears to be largely buried. The magnetometer data confirms that the wreck is built from steel or iron. No diving took place on the wreck site.

Wreck 5006 Devon Coast

Summary

The wreck of the Devon Coast lies in 16m of water (CD) south of Cuckmere Haven in East Sussex. It was found by the UKHO in 1976 and identified by means of a builders plate in 1981. In 2002 and 2003 Wessex Archaeology carried out a number of geophysical and diving surveys with the aim to test methodologies, to confirm the identification and to obtain details on the construction and appearance of the "Devon Coast".
 
Click the spots below to view underwater photographs.

Multibeam data showing the wreck of the Devon Coast. Click the spots to view details.Bollard Winch Boiler Propshaft

 

Results

The survey confirmed the identification of the Devon Coast and produced a basic plan of the wrecksite. The Devon Coast sank in a collision with the steamer Jeanie from Liverpool on the 4th of November 1908.
 
After the collision she was taken in tow by the Jeanie, but she sank before the protected waters of Cuckmere Haven could be reached.
 
Vessel specifications for the Devon Coast were obtained from Lloyds Register and the British Mercantile Navy List.

Boiler and Donkey Boiler

The large cylindrical main scotch boiler of the ship can still be found in its original location in the stern area. Two square furnace doors and the ends of steam tubes are visible on its northern face. The donkey boiler has collapsed and lies in front of the main boiler.

Bollard and fairlead

The collapsed bow area seems to be lying on its side. On the now vertical deck, a bollard and fairlead were observed.

Cargo Winch

One of the cargo winches of the Devon Coast is still standing upright on top of the cargo of cement bags where the deck collapsed.

Engine

The remains of the triple expansion steam engine with the propellershaft still attached can be seen aft of the boiler. The propeller is missing and has probably been salvaged.

Wreck 5007

Wreck 5007 is an unidentified and very broken up vessel. It was surveyed with sidescan sonar and magnetometer in 2002. The magnetometer data indicates that the wreck is made of ferrous metal.
 
The sidescan image shows a largely buried wreck, measuring 85m x 15m. A diver survey of the site was carried out in 2002. The diver observations confirmed that the wreck was dispersed with explosives. The hull consists of riveted steel plates. A boiler was observed in the wreck.

Wreck 5008

According to UKHO records, wreck 5008 represents the remains of an unknown trawler, lying on the starboard side. The wreck was surveyed and dived by Wessex Archaeology in 2002.
 
Wessex Archaeology divers described the wreck as the remains of a riveted hull steam trawler. Among other features, a proportion of the funnel leading into the engine room was observed.

Wreck 5009 Talis

Summary

Wrecksite 5009 is situated south-east of Beachy Head in East Sussex in 15.2m deep water (CD). The wreck was discovered by HMS Goldfinch in 1906, when a mast was showing above the surface. It was charted as dangerous wreck and the mast was removed in October 1906. In dive guides the wreck is usually called "1906 wreck" after its year of discovery. As adverse weather conditions on site prevented diving, Wessex Archaeology carried out sidescan and multibeam sonar surveys in 2002 and 2003.
 

Available Images

Results

The approximate vessel dimensions were taken off the sidescan and multibeam data. With this information and the wreck position, documentary sources were consulted to identify the wreck.
 
In the Shipwreck Index of the British Isles (Larn 1997), the Swedish steamer Talis was listed, which sank on the 22nd July 1906 at an approximate position of 50º 42’ N and 00º 26’ E near the Royal Sovereign Lightship in a collision with the SS Roman from Liverpool.
 
The Talis was carrying coal from Llanelly to Gävle in Sweden. There is no mention of casualties in the incident. The location of the wreck site as well as the dimensions measured on the multibeam and sidescan data correspond with the specification of the Talis. The iron propeller, indicating single screw propulsion also supports this interpretation. The fact that the masts of the wreck were still visible in August 1906 indicates a recent sinking, not more than a few weeks before the sighting. The date of sinking of the Talis fits this hyothesis. Although very little geophysical and archaeological information exists for this wreck site, the wreck can, with a fair degree of certainty, be identified as the Swedish steamship Talis.
 
With the name of the ship, the Lloyds Register of British and Foreign Shipping for the year 1906 was consulted to find out more details about the Talis.

Wreck 5010

Summary

Wreck site 5010 was located north-east of the Nab Tower in the deep draught vessel approach to the Nab Channel. The wreck lies in 13.6m deep water (CD) on a sandy seabed.
 
The site was discovered by the UKHO in 1969 and charted. It was described as a broken up wooden steamship. A boiler and a four-bladed propeller were found on site. Wessex Archaeology carried out geophysical surveys in 2002 and 2003 and a brief assessment dive in 2002. No further diving evaluations were undertaken on the wrecksite.
 
Boiler. Two holes are visible on top, these could be the remains of a pressure relief valve or steam valveBoiler. Two holes are visible on top, these could be the remains of a pressure relief valve or steam valve
 

Results

The evidence gathered from documentary sources and the Wessex Archaeology field assessment indicates that the wreck represents a steamship with single screw propulsion and scotch boiler. The ship might have been of composite build. These facts suggest a date of building after 1862, the year the scotch boiler was invented and patented.
 
To date no recorded losses corresponding to the archaeological evidence have been found.

Wreck 5011 The Portland Stone Wreck

Summary

Site 5011 lies in 7.7m deep water (CD) east of Selsey Bill an an area called "The Park". The seabed around the site consists of gravel. The wreck was located by the UKHO in 1976 and charted as an obstruction. In 1982 divers described it as a "very old wooden vessel".
 
A number of geophysical surveys as well as a short diving assessment and a longer evaluation were carried out by Wessex Archaeology in 2002 and 2003. The fieldwork involved the documentation of diagnostic features on site using drawing and sketches as well as underwater photography and video.
 
Click the spots below to view underwater photographs and video footage from the dive.

Plan of Wreck 5011Anchor Winch Port Side Structure Starboard Bow Stone Cargo Pump Stove

Results

The archaeological evidence collected during the WA surveys helped to characterise and interpret the wrecksite. A final identification of the wreck could not be achieved.
 
The so called Portland Stone Wreck was a carvel built, single masted sailing vessel, with the mast situated well forward in the front third of the vessel. The ship was approximately 15-16m long and 5.5m wide. It was fairly flat bottomed.
 
It probably represents the remains of a sailing barge or barge-like vessel, which sank in the second half of the 19th century with a cargo of Portland stone.

Anchor

A small iron admiralty type anchor located in the bow section. The stock is buried.

Port Side

Due to the angle of the hull on the seabed, the portside is better preserved than the starboard side. Frames, outer planks and ceiling planks are visible almost from bow to stern.

Possible Pump Tube

A hollow iron pipe was found forward of the stove. This is probably the pump pipe of the vessels bilge pump.

Starboard bow area

The starboard side is eroded to the level of the floor timbers. Outer planking and floor timbers are visible on the seabed. All outer planks were fastened with trenails.

Stone cargo

The cargo consisted of large stone slabs, presumably of Portland stone. The stones are still stacked in the position of the former hold. They are angled towards the starboard side.

Stone slab in-situStone slab in-situ

Multibeam data in 3D showing the angle of the stacked slabs.Multibeam data in 3D showing the angle of the stacked slabs.

Stove

A small cast iron stove was found in the stern area of the vessel. The position of the stove within the site indicates the location of the aft cabin.

Winch

An iron winch case was observed on the portside, about 3m from the presumed bow

Wreck 5013 The Bottle Wreck

Summary

Wrecksite 5013 is situated south-east of Selsey Bill in the Outer Owers. The general depth on site is 19.7m (CD). The wreck was first located by the Admiralty in 1944. In 1985 UKHO divers examined the site and described it as the remains of a wooden sailing barge with a cargo of cast-iron pipes, wine and beer bottles. The wreck has been extensively dived by sports divers and a number of items have been lifted from the site. Some artefacts can be seen in Littlehampton Museum. Wessex Archaeology carried out a geophysical survey of the wreck, but the site could only be dived once due to adverse weather conditions.
 
 

Results

The multibeam data shows a 14m long and ca. 6m wide stepped anomaly with a maximum height of 2m on the seabed. According to Wessex Archaeology diver observations this is probably the main cargo of stacked cast iron pipes, possibly gas pipes. No ship structure was observed during the assessment dive.
 
A consultation of various documentary sources did not produce any results. It is only through secondary sources that the wreck can be characterised as a small sailing coaster or barge that sank in the beginning of the 19th century. A length over 14m and a breadth over 6m has to be assumed for the vessel.

Wreck 5031

Wreck 5031 was surveyed with sidescan sonar and magnetometer in 2002. On the sidescan data the wreck seemed to be broken in two parts. It is lying on the port side. A debris scatter is visible around the site. Wreck and associated debris scatter measure 76m x 16m. The site was not dived in 2002.

Wreck 5043

A sidescan anomaly picked up during the 2002 wreck survey is the wreck of HMS Impregnable, a 98 gun ship built in Deptford in 1786. The sidescan data shows a number of rectangular features on the seabed. The magnetometer data indicates that these features are of ferrous metal.
 
The site was not dived in 2002, but it was investigated by the Hampshire and Wight Trust for Maritime Archaeology.