Complex sentence: The move to Upnor occurred in 1933, when the Arethusa was broken up and replaced a steel hulled nitrates clipper, the Pekin, which was renamed the Arethusa and was refitted in Chatham Dockyard.
Split into simpler sentences: The move to Upnor occurred in 1933, when the Arethusa was broken up and replaced a steel-hulled nitrates clipper, the Peking. It was renamed the Arethusa, and was refitted in Chatham Dockyard.