One of the more popular theories as to why Titanic's first funnel collapsed was due to base compression from the water pressure difference during the beginning of the plunge. I know that the funnels were made of a relatively thin metal, almost the same thickness as a thick cardboard. However, when we look at the sinking of the Lusitania, none of her funnels buckled in on themselves and went down intact. In fact, many of her survivors said that they could see all four of them go down virtually horizontally. Is this simply because of the design and materials used, or perhaps did something else occur in Titanic's case?