According to an example aspect of the present invention, there is provided a marine propulsion system (1) comprising a first portion (4) and a second portion (5) of a set of movable foils, a movement mechanism (2) coupled to the first portion (4) and the second portion (5) of the set of movable foils and configured to simultaneously control a motion of the first portion (4) and the second portion (5) of the set of foils along a closed first trajectory (6) comprising a first direction (17) and a second direction (18) which is different than the first direction (17), and a pitch mechanism (3) coupled to the first portion (4) and the second portion (5) of the set of movable foils and configured to control a pitch angle () of the first portion (4) and the second portion (5) of the set of movable foils, and wherein the pitch angle () of at least a part of the second portion (5) of the set of foils is dependent on an incoming fluid flow (v.sub.x), the motion of the second portion (5) of the set of foils, and a flow (v.sub.ind) induced by at least a part of the first portion (4) of the set of foils.

According to an example aspect of the present invention, there is provided a marine propulsion system (1) comprising a first portion (4) and a second portion (5) of a set of movable foils, a movement mechanism (2) coupled to the first portion (4) and the second portion (5) of the set of movable foils and configured to simultaneously control a motion of the first portion (4) and the second portion (5) of the set of foils along a closed first trajectory (6) comprising a first direction (17) and a second direction (18) which is different than the first direction (17), and a pitch mechanism (3) coupled to the first portion (4) and the second portion (5) of the set of movable foils and configured to control a pitch angle () of the first portion (4) and the second portion (5) of the set of movable foils, and wherein the pitch angle () of at least a part of the second portion (5) of the set of foils is dependent on an incoming fluid flow (v.sub.x), the motion of the second portion (5) of the set of foils, and a flow (v.sub.ind) induced by at least a part of the first portion (4) of the set of foils.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platform structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platform structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platfofin structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platfofin structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platform structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platform structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platform structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.

A tracked, amphibious vehicle, comprising at least two, spaced, elongated pontoons disposed generally parallel to one another. A platform structure can be supported by and structurally connects the pontoons, the platform structure including a transom, a lowermost generally horizontally extending panel above a free clearance area under a bottom panel and between the pontoons through which terrain and debris can pass. A hydraulic drive system can propel the vehicle, said drive system including left and right hydraulic motors mounted on the pontoons. At least one series of longitudinally spaced bogie wheels for supporting said vehicle can be mounted along the bottom of the pontoons. A continuous, endless belt can encircle each pontoon and engages the bogie wheels. Ground-engaging cleats assembled on the outer surface of each belt and covering the pontoon bottom provide traction to the vehicle. Gearing interfaces the motor with the endless belts. A supplemental, marine drive assembly includes: a hydraulic motor having a rotary device, shaft, with an axis, a propeller shaft having an axis wherein the motor axis and propeller axis are aligned, a universal joint connecting the hydraulic motor to the transom, and a housing including a sleeve that contains the propeller shaft, a first vertical plate connected to the sleeve and a second vertical plate connected to the sleeve below the first plate.