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.

Provided is a radar and communications enhanced sail for a sailboat, sail ship, or sail drone. The sail includes a first sail section comprising an active communication system, a second sail section comprising a passive communication system, or a combination thereof. The active communication system includes an antenna array (transceiver) and a software-defined radio (SDR), while the passive communication system comprises a reflective panel or sections and/or array of reflector panels or sections. The active system utilizes its SDR and transceiver to communicate back and forth with an onshore SDR and transceiver to provide information as necessary. The passive system receives a radar signal via the reflective material on the sail and reflects the signal back at the radar, which produces a radar cross section indicating that there is an object (in this case the sailboat) in the ocean.

A fin for use on a surfboard, the fin comprising: a leading edge, a trailing edge, and a base, the base comprising at least one mount for mounting the fin onto a surfboard; a first and a second outer fin surface which meet along the leading edge and the trailing edge and abut the base; and a first ridge protruding laterally from the first outer fin surface, and/or a second ridge protruding laterally from the second outer fin surface; wherein the shape and configuration of the fin creates an area of lower water pressure around and in front of the fin, as well as disrupting and/or reducing the size of trailing vortices, resulting in additional forward thrust for the board on which the fin is mounted.

Various embodiments of a submerged 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 keel are submerged below the water surface as the vessel is propelled by the wind-catching assembly above the water surface.

A traction system for a watercraft, including a sail and a fixed station that includes a mast and a winch which is connected to the sail by a traction cable, the system further including a bottom part that is supported by the traction cable, and fold lines, each of which has an end that is attached to a leading edge of the sail, and another end that is supported by the bottom part. The fixed station includes a base that accommodates the bottom element when the sail is retracted by the winch; and structure for grasping each fold line and pulling same towards the mast so as to retract the leading edge against the mast and fold the sail once the winch has retracted same close to the station.

A stress detection system includes a flexible two-dimensional structure, at least one electrically conductive textile filament, and an apparatus for generating and detecting an electric signal. The filament extends over a predetermined length in a portion of the flexible structure and has at least two points rigidly constrained to the structure. The apparatus is connected to the ends of the filament. The deformability of the filament is substantially equal to or greater than the deformability of the portion of the structure to which the filament is constrained.

In a marine propulsion apparatus that transmits power of at least one of an internal combustion engine (ICE) and a generator motor (GM) mounted on a ship to a propeller via a forward reverse switching mechanism, the marine propulsion apparatus can be downsized as a whole. The marine propulsion apparatus includes a connection switching mechanism capable of selectively connecting the GM to an upstream side and a downstream side of the power transmission from the ICE in the forward reverse switching mechanism. Then, the forward reverse switching mechanism is interposed between the ICE and the connection switching mechanism, and a large torque from the ICE is not directly transmitted to the connection switching mechanism. As a result, it is not necessary to increase the capacity of the connection switching mechanism, and the connection switching mechanism and thus the marine propulsion apparatus can be downsized.

In a conventional vessel anti-rolling apparatus, because a large memory capacity and a high-speed high-function computing processing unit are required, the cost of the vessel anti-rolling apparatus is caused to rise. A vessel anti-rolling control apparatus and an anti-rolling control method according to the present disclosure includes an azimuth controller that outputs a first steering-angle command value for making the vessel turn to an azimuth to which the vessel should travel, based on an azimuth command signal and a yaw-angle signal, an anti-rolling controller that outputs a second steering-angle command value for reducing rolling of the vessel, based on a rolling-angle signal, a rolling-angular-velocity signal, and a vessel-speed signal, and a steering-angle controller that controls a steering angle, based on the first steering-angle command value and the second steering-angle command value.

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.

Embodiments described herein relate generally to a sailing vessel that can substantially obviate the heeling problem experienced by classical sailboats. During navigation, the sailing vessel is driven forward by an aerodynamic force exerted by wind on the sail, and balanced by a hydrodynamic force exerted by water on a float on the stern of the sailing vessel, the aerodynamic force and the hydrodynamic force being parallel or substantially parallel to a longitudinal axis of the sailing vessel.