A duct arrangement for an internal combustion engine comprises an exhaust duct, an inlet duct and a cooling air duct. The exhaust duct is contained within the cooling air duct for substantially its whole length and the cooling air duct is contained within the inlet duct for substantially its whole length, so that in use the cooling air duct provides a barrier to limit heat transfer between gas flowing in the exhaust duct and gas flowing in the inlet duct. The invention avoids the need for separate inlet and exhaust ducts with their attendant disadvantages. The separation of the inlet and exhaust ducts by the cooling air duct allows the inlet air to be kept as cool as possible, as is necessary for efficient engine operation.

A duct arrangement for an internal combustion engine comprises an exhaust duct, an inlet duct and a cooling air duct. The exhaust duct is contained within the cooling air duct for substantially its whole length and the cooling air duct is contained within the inlet duct for substantially its whole length, so that in use the cooling air duct provides a barrier to limit heat transfer between gas flowing in the exhaust duct and gas flowing in the inlet duct. The invention avoids the need for separate inlet and exhaust ducts with their attendant disadvantages. The separation of the inlet and exhaust ducts by the cooling air duct allows the inlet air to be kept as cool as possible, as is necessary for efficient engine operation.

A vessel hybrid combined cycle power and propulsion system includes a steam turbine, a gas turbine, an auxiliary generator, an electric propulsion drive system, and an energy storage system, each connected to an AC bus. The system further includes a source of steam for the steam turbine, a control system for controlling operation of the steam turbine, gas turbine, auxiliary generators, electric drive propulsion system and energy storage system. The primary source of steam for the steam turbine is exhaust gas from the gas turbine. The primary source of gas for the gas turbine is boil off gas from the cargo hold. The AC bus includes a plurality of sections of AC bus coupled together by bus ties closed in normal operation forming a closed ring AC bus. The electric propulsion drive system includes a variable speed drive, driving an electric motor coupled through a drive shaft to a propeller.

A marine vessel comprising a command module, first and second buoyant tubular foils, and first and second struts for connecting the first and second buoyant tubular foils to the command module, respectively, wherein the first and second buoyant tubular foils provide substantially all buoyancy required for the marine vessel, and wherein the marine vessel further comprises first and second engines enclosed within the first and second buoyant tubular foils, respectively, and first and second propulsion units connected to the first and second engines, respectively, for moving the marine vessel through water, and means for reducing drag on the vessel as the vessel moves through water.

A vessel for transporting cargo by water comprises one or more propulsion devices with at least one air-breathing engine from the one or more propulsion devices disposed entirely above a surface of the water in a high-speed mode of operation. The least one air-breathing engine is configured to bleed airflow into a fluid circuit. The fluid circuit routes the bleed airflow to one or more fluid outlets disposed entirely below the surface of the water in the high-speed mode of operation. At least some of the one or more fluid outlets release the bleed airflow in the high-speed mode of operation generate a boundary layer along at least a portion of a hull of the vessel to reduce a skin friction drag thereof.

A vessel for transporting cargo by water comprises one or more propulsion devices with at least one air-breathing engine from the one or more propulsion devices disposed entirely above a surface of the water in a high-speed mode of operation. The least one air-breathing engine is configured to bleed airflow into a fluid circuit. The fluid circuit routes the bleed airflow to one or more fluid outlets disposed entirely below the surface of the water in the high-speed mode of operation. At least some of the one or more fluid outlets release the bleed airflow in the high-speed mode of operation generate a boundary layer along at least a portion of a hull of the vessel to reduce a skin friction drag thereof.