RIO DE JANEIRO — Brazil's navy was deciding Tuesday how to raise its biggest and oldest submarine, the diesel-powered Tonelero, from Rio de Janeiro's scenic Guanabara bay after it sank at its mooring on Christmas Eve.
Navy officials said divers were constantly checking on the state of the 2,410-ton British-built sub, which lay on an inclined seabed just 30 feet below the surface with its nose upward. The crew abandoned the ship before it sank.
Officials said they hoped to lift the Oberon-class sub soon, possibly by injecting compressed air into its water-filled compartments. The S-21 Tonelero was used mainly for training and had only four disarmed torpedoes aboard.
Navy officials said a valve malfunction in the hydraulic system apparently sank the nearly 30-year-old submarine. It had been undergoing hydraulic system repairs at the Arsenal base near the center of Rio de Janeiro.
On Sunday night, the nine-man crew on board noticed heavy flooding of some compartments and tried to make emergency repairs, but they had to leave an hour later as the submarine continued to submerge.
"There was no problem with the evacuation. The sub was moored just a meter (3 feet) from the pier," the officer said.
Brazil has a fleet of five military submarines, all of them diesel-powered, including one German-made boat and three Brazilian-made T-class subs.
Bought in 1972 for $125 million, Tonelero can carry 22 torpedoes and a crew of 70. It has a life expectancy of between 30 and 40 years.