Unidentified wreck: Thames Estuary


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:
Location Description:
West Barrow sandbank in the outer estuary of the Thames, off Essex.


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The building or site itself may lie within the boundary of more than one authority.

Location Description:
West Barrow sandbank in the outer estuary of the Thames, off Essex.
National Grid Reference:


The site consists of a partially intact wooden sailing ship (dated to the mid-C19 to early C20) up to 38m long and probably three-masted. The ship was carrying a cargo of roofing slates when it sank and this remains in situ. Although part of the hull and deck amidships are missing, the vessel is otherwise in a remarkable state of preservation, with deck planking, the rudder and part of the bowsprit in situ.

Reasons for Designation

The unidentified wreck: Thames Estuary, located on the southern edge of the West Barrow sandbank in the outer Thames Estuary, is scheduled for the following principal reasons:

* Survival: The wreck survives in an exceptional state of preservation, with a significant portion of the hull and a number of key characteristic features surviving in situ;

* Potential: Analysis of the wreck has the potential to enhance the knowledge and understanding of merchant seafaring during this period through examination of hull constructional details, fixtures and fittings and artefact assemblages. It also has considerable potential to inform on the mechanisms of preservation and decay of wooden shipwrecks and the changing environmental conditions impacting them over time;

* Rarity: Whilst mid-late C19 wooden cargo ships were once a common sight around the coast of England, very few survive in the clearly recognisable form of the Thames Estuary wreck;

* Documentation: The importance of this wreck is considerably enhanced by the information obtained from geophysical and archaeological survey;

* Historic interest: The wreck has potential to further understanding of the sourcing, trade and distribution of Cornish slate across north west Europe at a time when the slate industry was dominated by Welsh slate.


The site consists of a partially intact wooden sailing ship, up to 38m long and some 9m wide. It is probably three-masted and was carrying a cargo of roofing slates when it sank and this remains in situ. While wooden ships began to be replaced by composite, iron and steel vessels from the mid-C19, ships of all wooden construction continued to be built in north Wales, north west England and the Baltic states until 1914.

As the majority of slate extracted and exported from Britain in the late C19 and early C20 came from north Wales, the cargo was initially thought to comprise Welsh slate. Subsequent analysis has shown the slate to be probably Cornish in origin, probably from the Delabole quarry near Boscastle. The slate was cut by a powered rotary cutter, and hence post-dates 1880.

The wreck was first recorded during a routine survey of the southern edge of the West Barrow sandbank in the outer Thames Estuary, off Essex, by the Port of London Authority (PLA) in September 2016. The discovery was reported to Historic England by way of a third party in March 2017 and Wessex Archaeology was subsequently commissioned to undertake a staged investigation of the wreck (under the site code WA08) as part of the contract for Archaeological Services in Relation to Marine Protection.

The wreck is currently unidentified. The closest known record in time, date, cargo and location is the Myvanwy, a three masted schooner which ran aground on West Barrow Sand at 0400 on 21 May, 1904. The Myvanwy was built in Newport in 1870 and was bound for Woolwich from Antwerp with a cargo of slate. The ship was described as a total wreck, and that some of her cargo was salvaged (although the hold lay underwater at low tide).


Protected area: 50 metres within 51.554842, 01.050136.

No part of the restricted area lies above the high-water mark of ordinary spring tides.

The wreck measures 38m in total, 34m from bow to sternpost. The bow lies to the south-west. It has a noticeable, but not exaggerated, rake and survives to full height with part of its bowsprit surviving in situ and possible surviving knightheads (upright members flanking and securing the bowsprit) on either side. The wooden rudder also survives in situ to almost full height, at least 3m above seabed and angled slightly to port. The head of the rudder is eroded and the stock/tiller is missing, although an upstanding structure just forward of the sternpost may be part of a tiller mechanism. The rudder is attached to the fully exposed vertical sternpost by two sets of cuprous gudgeons and pintles. The stern appears to be rounded with cant (that is, fore and aft) frames and inner and outer planking.

Much of the starboard side of the hull planking is missing, although iron knees or riders survive in situ on both sides. There is a large hold, possibly delineated by transverse bulkheads. Within this is a substantial cargo of tightly packed slates, stacked horizontally in rows across the breadth of the ship. Along the port side of the hull, outer and inner planking and frames with ferrous fastenings and fragments of iron strapping or other reinforcements are visible. Collapsed ship timbers are lying on the cargo, on the hull and on the seabed outboard.

The slate cargo indicates that the site is the wreck of a bulk cargo vessel. The presence of two masts, one amidships and one aft, suggests that a third mast was originally forward and that the wreck is of a three-masted sailing ship. Such vessels were in common use until the First World War, after which they went into rapid decline. The presence of iron knees or riders on a merchant vessel indicate that a pre-1800 date is highly unlikely and that a mid- to late 19th century date is more probable. On a balance of probability basis, the mid-19th to early 20th century is the probable date range for the construction and loss of this vessel.


Books and journals
Brown, P, Britain's Historic Ships, (2009), 56-58
MacGregor, DR, 'The Wooden Sailing Ship: Over 300 Tons' in Gardiner, R, Sail's Last Century: The Merchant Sailing Ship 1830-1930, (1993), 20-41
MacGregor, DR, 'The Wooden Sailing Ship: Under 300 Tons' in Gardiner, R, Sail's Last Century: The Merchant Sailing Ship 1830-1930, (1993), 42-51
'Merchant Shipping News' in Shipping and Mercantile Gazette and Lloyds List, , Vol. 20804, (23 May 1904), 9
'Merchant Shipping News' in Shipping and Mercantile Gazette and Lloyds List, , Vol. 20806, (25 May 1904), 8
Delabole Slate, accessed 16/03/2018 from http://www.delaboleslate.co.uk/default.asp
Description of British Slate Types, accessed 1 October 2020 from http://www.britishslateforum.co.uk/category/sources-of-slate/british-slate/
History of the British Slate Industry and Analysis of Slate Imports and Exports, accessed 1 October 2020 from http://www.slateroof.co.uk/Foreign_trade_2.html
Slate Industry of North Wales, accessed 8th January 2018 from http://whc.unesco.org/en/tentativelists/5678/
Historic England National Record of the Historic Environment (NRHE) No 897000
Port of London Authority (2016) New Obstruction Report, 25th September 2016
Unpublished informal report on the Thames Estuary Wreck slate by Delabole Quarry, April 2018
Wessex Archaeology (2017) Slate Wreck WA 08 Thames Estuary, unpublished report for Historic England, ref 108281.07


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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