boat captain disembark dock ferry harbour hull marina passenger sea Torquay water embark gangway Jetty passage port railing route transport travel adjustable aerobridge air jetty airbridge aircraft door airport angle board boarding bridge cab connected connecting connection disconnect disconnected disembarking enclosed extend extendable exterior gate gate attendant gateway height high interior jet bridge jetway loading bridge movable movable connector passenger boarding bridge passenger walkway passengers portal retractable retractable tunnel retracted retracting safety security slope sloping terminal walkway