Cobb returned to
Bonneville salt flats again in 1947, where on 16 September he beat his own standing 1939 World Land Speed Record by reaching (on one of the two runs he was clocked at having reached ), earning him the press moniker "The Fastest Man Alive". This record remained in place until 1963, when it was surpassed by the American
Craig Breedlove. After the 1947 achievement, Cobb turned his mind to becoming on water what he now was on land and went after the simultaneous World
Water Speed Record. He commissioned from
Vospers the jet-engine powered speedboat
Crusader and selected the long water loch of
Loch Ness in Scotland for the speed trial. On 29 September 1952 he was killed at the age of 52 whilst attempting to break the world Water Speed Record at Loch Ness whilst piloting
Crusader at a speed in excess of . During the run the boat lost stability and disintegrated about Cobb. After extensively studying footage of the crash,
Reid Railton, the designer of the boat, concluded the crash was caused by an undamped oscillation which caused a loss of control authority. Cobb's body, which had been thrown beyond the wreckage, was recovered from the loch, and subsequently conveyed back to his home county of Surrey, where it was buried in the graveyard of Christ Church, Esher. A memorial was subsequently erected on the Loch Ness shore to his memory by the townsfolk of
Glenurquhart. In 2002 the remains of the jet engine speedboat
Crusader were located on the bed of Loch Ness at a depth of and the site was designated as a
scheduled monument in 2005. The wreck was filmed by a research team from
National Geographic in 2019. ==Personal life==