A propulsion system for a marine vessel has a transom bracket to be connected with a transom of the marine vessel. A drive unit is rotatably connected with the transom bracket so as to be pivotable from a lowered position into a raised position, or vice versa, around a pivot joint. An actuator is configured to move the drive unit around the pivot joint, wherein a brake device is arranged in connection with the pivot joint. The brake device is configured to maintain the drive unit in position independently of a state of the actuator.

Passenger restraint systems are provided. The restraint systems can include: a passenger seat supported by a frame; a restraint bar pivotably attached to the frame; and at least one piston operably engaged between the restraint bar and the frame. Restraint system pistons are provided. The pistons can include: a central chamber housing a piston head and rod; a fluid reservoir in fluid communication with the central chamber; and at least one electromechanical valve operable between an open and a closed position. Methods for restraining a passenger within a seat are also provided. Manually operable piston assemblies are provided that can include a piston head within a cylinder, the piston head separating fluid in the cylinder to define rod-side fluid and head-side fluid. The piston assembly can be configured to operate in at least six positions, including but not limited to a first position of locking retract static; a second position of locking retract extend flow; a third position of locking retract flow; a fourth position of locking extend static; a fifth position of locking extend retract flow; and a sixth position of locking extend flow. Manually operable piston assemblies are also provided that can include a piston head within a cylinder, with the piston head separating fluid in the cylinder to define rod-side fluid and head-side fluid. The manually operable piston assembly can further be configured to operate in at least six positions that include a first position of locking extend static; a second position of extend movement flow; a third position of manual override retract flow; a fourth position of manual override extend flow; a fifth position of locking retract static; and a sixth position of retract movement flow. Methods for operating a manually operable piston are also provided. The methods can include applying pressure to retract the piston rod and allow head-side fluid to pass through piston head passageway and mix with rod-side fluid. Methods for operating a manually operable piston can also include applying pressure to extend or retract the piston rod and allow head-side fluid to pass through at least one valve and mix with rod-side fluid.

Systems and methods disclosed herein are directed reusable hold down mechanisms. A locking material, such as a low melting point metal, can be used to hold an actuating rod in place while the locking material is below the melting point. A heater can be used to increase the temperature of the locking material to at least the melting point, causing the locking material to no longer hold the actuating rod in place. A biasing element, such as a spring, can then cause the released pin to move in a specific direction, which can then contact a physical element or component to actuate a physical device. The actuating rod can be reset while the locking material is in a liquid, viscous, or similar state, allowing the hold down mechanism to be reused without removal or the need for specialized tooling.

A hydraulic system for a passenger restraint device includes a hydraulic pump and a hydraulic section. The hydraulic section includes a hydraulic accumulator, a valve arrangement and a hydraulic cylinder unit with a piston. The valve arrangement is connected to the hydraulic pump, the hydraulic accumulator and the hydraulic cylinder unit. The piston can be moved between an open position and a first closed position. The hydraulic pump can pressurize the hydraulic cylinder unit so that the piston moves from the first closed position to the open position. The hydraulic accumulator is configured so that the piston moves from the open position to the first closed position. The hydraulic cylinder unit can be pressurized in a first switching position of the valve arrangement with a first pressure stage and in a second switching position of the valve arrangement with a second pressure stage lower than the first pressure stage.