LONDON (AP) — Prime Minister Boris Johnson wants to build a national flagship to travel the world’s oceans promoting British trade and investment. But critics are suggesting it is he who is at sea. Johnson announced his plans over the weekend, saying the vessel would be the first of its kind and reflect the U.K.’s “status as a great, independent maritime trading nation.’’ The project harkens back to a previous golden age, where the royal yacht projected the majesty of Empire and when Britannia ruled the waves. That’s precisely the problem, according to Peter Ricketts, a retired diplomat and independent member of the House of Lords. Ricketts says it doesn’t present the high tech face of Britain to the world