The last major Dumbarton shipyard was William Denny and Brothers which closed in 1963, and the remaining smaller yards followed over the next few decades. Until recently, the old Denny's shipyard tender "The Second Snark" was still in use on the Firth of Clyde as a passenger ferry and cruise boat. Denny's was an innovative company that had a reputation for research and development; high-pressure turbines and hull stabilisation were two areas where they were highly respected. They even built an early design of helicopter in 1909 and in their final years they were involved in hovercraft development in the form of the Denny D2 Hoverbus. A film clip of this vessel on its maiden trip to Oban exists in the Scottish Film Archive.