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.

A multi-purpose personal watercraft for deployment in different configurations as desired by a user. The multi-purpose personal watercraft comprises a base frame which forms a watercraft base which includes side extensions, an aft floor board, and a bow portion, as well as two opposing mirror image side floats with which the base frame is selectively integrated. When in place, the opposing side floats form the multi-purpose personal watercraft's U shaped hull and enable the selective attachment of a rudder assembly behind the multi-purpose personal watercraft's stern. With respect to propulsion, base frame is configured to enable the selective deployment of pedal propellers, a user's legs, or a trolling motor. A dual steering system enables the control of up to two discrete steering mechanisms from a single position on the watercraft.

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.

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.

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.

A digital twin computation section collects a speed of an own ship, a position of the own ship, and a heading of the own ship in real time, and reproduces an actual hull motion of the own ship realized at a current steering angle on a navigational electronic marine chart. A simulation computation section displays, on the navigational electronic marine chart, an assumed hull motion of the own ship determined by calculation that assumes that a force acting on the hull is a driving force at the current steering angle. A resultant force of external forces computation section calculates an acting direction and a magnitude of a resultant force of external forces acting on the hull based on a ship speed difference, ship position difference, and heading difference between the actual hull motion and the assumed hull motion.

Techniques are disclosed for systems and methods to provide accurate positioning for a hydraulic steering system without a need for a steering reference transducer. A hydraulic steering system may include a logic device in communication with an autopilot pump controller. Control and sensor signals provided by the pump controller are used to determine a linear or uncompensated steering actuator speed and an estimate of the hydraulic elasticity of the steering system, which can be modeled as an estimate of the air volume trapped within the steering system. The hydraulic elasticity/air volume estimate is used to determine a corrected or compensated steering actuator speed, and the corrected steering actuator speed is used to accurately control the steering system.

Techniques are disclosed for systems and methods to provide accurate positioning for a hydraulic steering system without a need for a steering reference transducer. A hydraulic steering system may include a logic device in communication with an autopilot pump controller. Control and sensor signals provided by the pump controller are used to determine a linear or uncompensated steering actuator speed and an estimate of the hydraulic elasticity of the steering system, which can be modeled as an estimate of the air volume trapped within the steering system. The hydraulic elasticity/air volume estimate is used to determine a corrected or compensated steering actuator speed, and the corrected steering actuator speed is used to accurately control the steering system.