Heavy vibrations as a by-product of the four steam turbines on "Lusitania" and "Mauretania" would plague both ships throughout their voyages. When "Lusitania" sailed at top speed the resultant vibrations were so severe that second- and third-class sections of the ship could become uninhabitable. In contrast, the "Olympic"-class liners utilised two traditional reciprocating engines and only one turbine for the central propeller, which greatly reduced vibration. Because of their greater tonnage and wider beam, the "Olympic"-class liners were also more stable at sea and less prone to rolling. "Lusitania" and "Mauretania" both featured straight prows in contrast to the angled prows of the "Olympic"-class. Designed so that the ships could plunge through a wave rather than crest it, the unforeseen consequence was that the Cunard liners would pitch forward alarmingly, even in calm weather, allowing huge waves to splash the bow and forward part of the superstructure. This would be a major factor in damage that "Lusitania" suffered at the hands of a rogue wave in January 1910.