Bluebird K7
The plan for the world record attempt was for Bluebird to stop at the far end of the lake and refuel from another boat that had been put there for that purpose.  Taking time to refuel would also give the lake, which had been disturbed by the first run, time to settle down again.  On the actual record attempt, Campbell decided not to refuel and instead started on his second run immediately.  Why he did this is unknown.