The new ship will give youngsters from all walks of life the chance to go to sea as part of youth development programmes.
The naming, approved by the Prince of Wales, continues a link between youth training and the Royal Family. For the vessel, a traditional tall ship, has been built for the Sail Training Association (STA) - whose patron is Prince Philip. The Prince William will replace the Sail Training Association's tall ship, the schooner, Sir Winston Churchill.
Sir Robin Knox-Johnston, the first man to sail solo non-stop around the globe, is the STA's President. He said this morning, "This royal endorsement of our work is a unique accolade for the STA. It recognises our heritage and world leadership in personal development sail training for young people from all backgrounds."
The Prince William and her sister brig each accommodate 48 young trainees with a small professional crew. The STA's famous schooners Sir Winston Churchill and Malcolm Miller have now been retired.. Between them, they took 60,000 young people to sea and sailed over 1.5 million nautical miles since they were launched in the mid-1960s.
The ship was built largely through a grant from the Sport England Lottery Fund, corporate and individual donations. Along with her sister ship, the Stavros S Niarchos, which came into service last year, the Prince William will continue the STA's tradition dedicated to the personal development of young people through the sail training experience on tall ships.