Blue Bird K4

Blue Bird K4 was a powerboat commissioned in 1939 by Sir Malcolm Campbell, to rival the Americans' efforts in the fight for the world water speed record.

Conventional planing powerboats, such as Miss England or Blue Bird K3, have a single keel, with an indent or "step" projecting from the bottom of the hull.

At speed, the force on this step is enough to lift the bow upward, reducing the wetted surface area of the hull and thus also the frictional drag.

After the Second World War, Sir Malcolm unsuccessfully re-engined K4 with a de Havilland Goblin turbojet engine but did not gain any records.

Under the terms of his will, Sir Malcolm's possessions, including the record breakers, were auctioned off and Donald was forced to buy them back.