JETFOIL FOR BELGIUM—The first of two Boeing Jetfoil hydrofoils for Regie voor Maritiem Transport (RMT), the state-owned ferry company of Belgium, was launched recently by Boeing Marine Systems in Seattle, Wash. The 316-seat hydrofoil, Princesse Clementine, will enter commercial service on May 31 between Dover, England, and Ostend, Belgium. Operating under the name "Sealink," RMT will provide up to six trips a day on the 62-nautical-mile route when the second Jetfoil, Prinses Stafanie, is added to the service this summer. Direct train connections will enable travelers to make the trip between Ostend and London in just three and one-half hours at approximately $43 one-way fare. RMT presently operates regular car-carrying vessels between Ostend and Dover/Folkestone.