wooden landing stage itself became known as a "dolphin". The towers were joined above the eventual waterline by a steel platform deck upon which other structures could be added; this became a gun deck, on which an upper deck and a central tower unit were constructed. QF 3.7 inch anti-aircraft guns were positioned at each end of this main deck, with a further two Bofors 40 mm anti-aircraft guns and the central tower radar installations atop a central living area that contained a galley, medical, and officers quarters. The design of these concrete structures is equal to a military grade bunker, due to the ends of the stilts, (under water) that are solidly locked into the ground. Many species of fish live near the forts because the forts create cover. They have provided landmark references for shipping. They were laid down in dry dock and assembled as complete units. They were then fitted out—the crews going on board at the same time for familiarization—before being towed out and sunk onto their sand bank positions in 1942. The naval fort design was the latest of several that Maunsell had devised in response to Admiralty inquiries. Early ideas had considered forts in the English Channel able to take on enemy vessels. During World War II, the Thames estuary Navy forts destroyed one German E-Boat. Rough Sands Fort (U1) Rough Sands fort was built to protect the ports of Felixstowe, Harwich and the town of Ipswich from aerial and sea attack. It is situated on Rough Sands, a sandbar located approximately from the coast of Suffolk and from the coast of Essex. Fort Roughs or the "Rough Towers" was "the first of originally four naval forts designed by G. Maunsell to protect the Thames Estuary." The artificial sea fort was constructed in dry dock at Red Lion Wharf, Gravesend, and was commissioned "H.M. Fort Roughs" on 8 February 1942. After an eventful journey it was grounded under the supervision of Maunsell at 16:45 on 11 February 1942. With "almost 100 men" having earlier embarked at Tilbury docks, the fort entered into service immediately. In 1966 Paddy Roy Bates, who operated Radio Essex, and Ronan O'Rahilly, who operated Radio Caroline, landed on Fort Roughs and occupied it. However, after disagreements, Roy Bates seized the tower as his own. O'Rahilly attempted to storm the fort in 1967, but Roy Bates defended the fort with guns