A floating dock is one that can be flooded to receive the hull of a ship and then pumped dry, though in early examples like this ship would have been floated in at high tide and the dock drained on the ebb before being closed at the end with transverse timbers. It would then remain dry and float up as necessary on the next tide to continue work on the ship in it. The fairly small one shown here is probably being breamed (having the lower hull cleaned by controlled fire). The first use of such a dock was at Cronstadt, the Russian naval port, in the reign of Peter the Great where a British captain in his service used the hull of an old ship as a floating dock. In 1785 a shipbuilder and wharfinger at Rotherhithe called Christopher Watson installed such a dock there, and rapidly found himself indicted for obstructing navigation on the river by the Corporation of London in their official role as conservators of the Thames. The case, reported as a 'great cause', was held over three days before Mr Justice Gould at Kingston Assizes at the end of March 1786. The 'General Evening Post' (30 March-1 April) stated that 'Mr Mingay for the prosecution, and Mr Erskine, for the defendant, made speeches replete with wit and perspicuity for their respective clients. For many years there has not been a cause wherein scientific knowledge on the subject of navigation has been more fully entered into and more obstinately disputed.' However, after five hours deliberation the jury found Watson guilty. The consequences remain to be clarified, so it is not certain that this rather later image represents Watson's dock, though most 19th-century references assume that it does. If so it is also likely to be the one shown with the slave ship 'Sandown' in it in January 1793 in an illustrated log (LOG/M/21) by Samuel Gamble and possibly that recorded in a 1790s drawing by John Charnock, PAF2953.

Francia, who drew this image worked in England from 1790 to 1817 when he returned to his native Calais. This is one of his early plates for Cooke's 'Views on the Thames' which is normally dated 1818-22, but which contains others dated to 1829 (allowing the later ones may have been restruck) and some by Samuel Owen first published from 1809. The accompanying text simply states that there were eleven shipyards in Rotherhithe at the time and that it had this floating dock, which the view suggests was upstream (west) of St Mary's Church, shown in the background. The final contents page of the book in fact says 'near Rotherhithe' rather than 'at Rotherhithe'. [PvdM 2/12]