An artist's impression released today reveals a stately craft covered in gold and royal livery.
Her Maj, 85, will take part in a spectacular River Thames pageant to mark 60 years on the throne when a 1,000-strong flotilla will recreate scenes on June 3 not seen on the Thames for centuries.
The 210ft design is based on the lavishly decorated royal barges of the 17th and 18th Centuries and will boast the Queen's cipher - EIIR ? on the bow.
The Queen will sit alongside Prince Philip on the top deck in ornate chairs under a gold canopy surrounded by other royals.
Flowers from the Queen's gardens will provide decoration on the cruiser Spirit of Chartwell which has been donated for the event by owner Philip Morrell, founder of the Magna Carta Steamship company.
Pageant master Adrian Evans said: "The royal barge must be a jewel - the most magnificent vessel in the flotilla."