Some 50 fire fighters, according to the BBC worked to extinguish the blaze, which started among acetylene cylinders along the outside of a warehouse.
Of 240 cylinders on site, many of which are empty, it is believed there were between 30 and 40 cylinders either on fire or at risk of being ignited. Witnesses reported hearing 'massive explosions,' according to the BBC, which also quoted a spokesman for Cornwall Fire and Rescue Service as saying that the fire had reached a "stable state."
Elaborating on the statement, Kevin Thomas of Cornwall Fire and Rescue Service said, "But that's not to say things won't get worse again."
Emergency crews are expected to remain on site for 24 hours to monitor the fire.
The dockyard, which is capable of handling ships up to 230 metres in length, also has facilities for repairing ships. Most cruise ships, however, anchor in the bay and ferry passengers ashore by tender.
There's no cruise ship in port today but Silversea's Silver Cloud is due in Sunday, June 26, and Swan Hellenic's Minerva on July 4. A spokeswoman for Silversea Cruises in the U.K. told Cruise Critic that the line was 'monitoring the situation'.
--by Sue Bryant, Cruise Critic Contributing Editor