Fastest circumnavigation of Great Britain by powerboat

The fastest circumnavigation of mainland Britain (not including Ireland) took 27 hr 10 min at an average speed of 53.5 knots (99.1 km/h or 61.6 mph) and was accomplished by Neil McGrigor, Tony Jenvey, Jeremy Watts and John Guille (all UK) in Bradstone Challenger a Bladerunner 51 powerboat. The 1,469 nautical mile (2,721 km or 1,691 mile) journey started in Southampton on 11 August 2005 and finished there the following day.

Official UIM record (see www.roundbritainrecord.com
for more info).