The remains of the Louisa were given Scheduled Ancient Monument status on 27 December 2001. The scheduled area is a rectangle centred on the wreck at ST18147402 and measuring 60m along the shore and extending 40m out into the River Taff.

The vessel represents a transitional period in shipbuilding between timber and iron, and survives largely intact up to the hanging iron knees for the lower deck beams for almost half the original length of the vessel and two thirds of the length at the keel. The system of planking used for the vessel includes skins of both diagonal and horizontal strakes. The interior of the vessel is filled with mud. The offshore end of the vessel has been washed away. Since the impoundment of Cardiff Bay, the site is submerged at all times.

Event and Historical Information:
The Louisa was built on Prince Edward Island, Nova Scotia, Canada in 1851 by James Yeo for family member, William Yeo, of Appledore, Devon. It is likely that the square-rigged Louisa was used originally used in the transatlantic timber trade bringing Canadian timber to Bristol and Bideford. Lloyd's Register describes the Louisa as measuring 147ft long by 30ft beam and 21ft depth. Louisa last appears in the Lloyd's Register in 1902 when owned by Joseph Rees of Aberaeron. The hulk was investigated by survey and excavation by the University of Sheffield in 1998. The investigation was funded by the Cardiff Bay Development Corporation.

Sources include:
CADW SAM Site Description December 2001
Photographs taken by the RCAHMW in 1999

Maritime Officer, 10 July 2007.