Abstract: Various embodiments of an apparatus and method for achieving and maintaining a desired depth of a submersible vessel are disclosed. The submersible vessel has both a ballast control system designed to alter a buoyancy of the submersible vessel and one or more vertical marine thrusters, designed to position the submersible vessel at a desired depth. Using the combination of the ballast control system and one or more thrusters, a desired depth may be achieved and maintained more quickly, more quietly and more accurately than vessels using only a ballast control system or one or more thrusters, respectively, alone.

Abstract: A self-righting sailing vessel is described. The self-righting sailing vessel may determine the occurrence of several predetermined events, such as the self-righting sailing vessel capsizing, present or imminent inclement weather, and/or a present or imminent vessel or large marine animal. Upon detection of one of these events, the self-righting sailing vessel causes at least it's hull to become partially or completely submerged beneath the water. The self-righting sailing vessel is configured such that its rig is more buoyant than the rest of the vessel when the vessel is completely submerged beneath the water, causing the vessel to move towards an upright position while underwater. When the vessel is pointing towards an upright position, the vessel may begin ascending until it surfaces and is ready to continue sailing on top of the water.

Abstract: Various embodiments of a submerged submersible sailing vessel are disclosed. Such a submerged sailing vessel may comprise a submersible hull assembly, a keel coupled to and extending upwards from hull assembly towards a water surface, and a wind-catching assembly coupled to and extending upwards into the air from the keel for propelling the submerged sailing vessel. The hull assembly and the keel are submerged below the water surface as the vessel is propelled by the wind-catching assembly above the water surface.