Find Spot MPM2074 - Mushroom anchor, Portsmouth Harbour

Mushroom anchor recovered by a crane barge in Portsmouth Harbour while investigating an anomaly during the Queen Elizabeth Class Capital Dredge Project. Made from forged iron or steel. The anchor had a hemispherical crown, complex tapering stock, counterweight and d-shaped shackle ring. It was approximately 1.9m tall and about 1.0m square at the four-sided crown. The crown was concave on the underside, with a lifting/tripping ring set into it. Counterweight measured 0.3m wide by 0.3m long and 0.16m thick. Shackle ring 0.13m long by 0.1m wide.

The anchor was recovered from the channel just north of the harbour mouth and due its location was thought to have probably been lost or abandoned rather than deliberately placed. This appeared to be an isolated find but may have been associated with a wire/cable.

As mushroom anchors are known to have been used to secure the boom defence across Portsmouth Harbour during the Second World War it is possible this anchor may have been used for this purpose during either the First or Second World War. It may also have been a submarine anchor as the find spot was close to the site of the former HM Submarine base at Gosport.

UID: BWL1_0021 in Queen Elizabeth Class Capital Dredge Project report.

Wessex Archaeology, 2018, Queen Elizabeth Class Capital Dredge Project Her Majesty's Naval Base, Portsmouth: Archaeological Assessment Report (Unpublished document). SPM646.