Why did the lusitania sink so quickly?

Answer 1

While the blame for the sinking of the RMS Lusitania sits squarely on the shoulders of Germany during the First World War and U-20 Kapitan Walter Schweiger, the cause of the rapid sinking has always been debated. Schweiger, intercepted German communications at the time of the sinking and even the British Admiralty concede only one torpedo was fired. Under most circumstances, a ship of 32,500 tonnes would be significantly damaged with one torpedo, but either survive to limp back to port or sink rather slowly. Indeed, the Lusitania was carrying some ammunitions and magazine rounds, but the cargo hold in which they were stored was found to be intact by maritime explorer Robert Ballard and others. The second explosion that most survivors heard was hypothesised to be either the ammunition, a coal dust explosion or a boiler or steamline explosion, the lattermost of which is the most likely candidate. However, even with a steam explosion, the ship would not necessarily have been damaged further by this.

Historians, explorers and authors all seem to ignore the biggest smoking guns of all. Why did the RMS Lusitania sink so quickly? First, we need to look at four things, three of which were salvaged from the ship in 1982 - her four propellors and the great speed at which they drove Lusitania. The Lusitania and her sister ship, RMS Mauretania, were the two fastest ships on the Atlantic since 1907. In fact, Mauretania held the Blue Riband speed record for the fastest North Atlantic crossing from 1907 to 1929 - an unprecedented span of time. Lusitania was only a hair shy of that record and even held it for the first two years sporadically. While Boiler Room 4 had been shut down to conserve coal, Lusitania was still travelling at 18 knots when she was hit. Why does this matter? Contrary to Kapitan Schwieger's log indicating the "ship stops immediately and heels to starboard," she didn't stop. The torpedo damaged the steamlines controlling the propellors and Captain Turner was unable to stop the ship or turn the ship's rudder to try and beach her on the nearby Irish coast. Her speed was forcing water into the hull. For her height and size, Lusitania had a very deep draught. With her turbines unable to be shut down, the ship, with the giant hole opened by the torpedo, was acting like a giant scoop and forcing water into the hull, possibly causing the bulkheads to fail and collapse. Open portholes would not have helped the matter. In fact, the lifeboats could not be lowered for the first 10 minutes of the ship sinking, as they would have flipped on launch upon hitting the water. This left less than eight minutes to launch 48 lifeboats, with a man on each side at the davits controlling the falls, standing precariously on a deck pitching forward and downward, listing to starboard beyond 15 degrees, and palpably sinking in jerking motions. This contributed to crewmen losing their grip and many of the lifeboats capsizing on launch on the starboard side or crashing against deckhouses on the port side. In fact, only six lifeboats stayed afloat.

Secondly, the torpedo also happened to hit at a weak spot in the ship - where the longitudinal bulkheads could not be curved with the narrowing taper of the bow, but rather "stepped in," as indicated in the remarkable book by J. Kent Layton, "Lusitania: Ship of Splendour." Hitting at this spot was where a number of bulkhead met, thereby meaning that more than two compartments were ruptured. Combine this with the speed and the inability to stop the ship, and you have the disastrous outcome that took place.

As an interesting final note, Cunard's RMS Aquitania, built in 1914 as a larger running mate and near-sister ship to Lusitania and Mauretania, John Brown on the Clyde designed her to withstand flooding with all six of her longitudinal bulkheads ruptured, resulting in a list of 23 degrees with still positive metacentric height. However, with Lusitania and Mauretania, if three side compartments flooded, the list would exceed 22 degrees and their metacentric height would become negative, meaning that the ships were in danger of capsizing.

Lusitania's continuing propulsion in the water after the torpedoing and the inability to stop the ships powerful turbines forced water into the giant hole at a phenomenal rate that may not have been as rapid had she been stopped. Combined with the torpedo strike occurring at perhaps the most vulnerable part of the ship and the design structure of the bulkheads, these were the main contributing factors in her rapid sinking, after having ruled out a second torpedo strike, a coal dust explosion, additional damage from the steam explosion, or the detonation of ammunition aboard.
The Lusitania sunk quickly because of where she was hit by the torpedo. The captain of U-20 (the U-boat that sunk Lusitania said "Torpedo hits starboard side right behind the bridge. An unusually heavy detonation takes place with a very strong explosive cloud. The explosion of the torpedo must have been followed by a second one [boiler or coal or powder?]... The ship stops immediately and heels over to starboard very quickly, immersing simultaneously at the bow"

Another reason she sank so fast was the way her watertight bulkheads were designed. Like most other ships she had transverse bulkheads but Lusitania also had longitudinal bulkheads running from the back to the front. This meant that when she was torpedoed only one side filled with water so it listed very quickly.