Peel Ports have commissioned Beckett Rankine to design refurbishment works for the four sliding caisson gates to the two tidal locks which provide access to Chatham’s Commercial Docks. The locks and their operating machinery were constructed for the Royal Navy in the 1870s although the current caisson gates are replacements dating from the 1960s. Our work includes diving surveys of the gate cills and recesses to identify repair works required while the caissons are removed for their refurbishment. As there is no nearby operational dry dock that can accommodate the gates we are investigating the reinstatement of an old abandoned dry dock facility for the purpose. Throughout the refurbishment the commercial docks are to remain operational.