A submersible vessel having wing and keel assemblies that are extendable for wind-powered surface operation and retractable to reduce drag for submerged operation or to place the vessel in a more compact configuration. A deployment mechanism including an actuator and linkage pivots the wing and keel assemblies simultaneously between the deployed and retracted configuration. The vessel may have first and second pressure hulls flanking the wing and keel assemblies. A drive mechanism including a motor and a gear train employing pulley-and-cable assemblies rotates either the wing and flap together such that the flap angle relative to the wing is constant, or to change the flap angle relative to the wing with the wing angle of incidence held constant. The invention also provides a retractable wind-powered propulsion apparatus that is mountable to the hull assembly of a submersible or non-submersible vessel.