An outboard engine includes a steering mechanism having a pod propulsion device disposed in water outside a hull; a propulsive drive mechanism that is disposed in the hull and gives a propulsive drive force to the pod propulsion device; and a circulation cooling circuit which has an outward flow path that supplies a cooling oil to the steering mechanism and the propulsive drive mechanism, and an inward flow path which recovers the cooling oil from the steering mechanism and the propulsive drive mechanism, in which the inward flow path and the outward flow path of the circulation cooling circuit communicate with each other inside a case body of the pod propulsion device.

A port insert for a marine lower unit includes a hollow body having a first end and a second end, the second end having a first exterior thread configured to couple with a cap and one or more apertures formed in the body adjacent the first end. The port insert also includes a spring mechanism disposed within the hollow body. The port insert further includes a sealing member coupled to the spring mechanism, the sealing member being biased toward the second end in a non-use state.

Disclosed is a method of discharging lubricant oil from a BOG reliquefaction system configured to reliquefy BOG by compressing the BOG by a compressor, cooling the compressed BOG through heat exchange with non-compressed BOG by a heat exchanger, and reducing a pressure of fluid cooled through heat exchange by a pressure reducer. In the lubricant oil discharge method, the compressor comprises at least one oil-lubrication type cylinder and it is determined that it is time to discharge condensed or solidified lubricant oil, if at least one of preset conditions is satisfied.

A fluid transportation apparatus includes a first suction pipe having a first intake opening and a second suction pipe having a second intake opening. The first and second suction pipes are attached to a vessel on opposite sides to move in rolling motion. The first intake opening is disposed in a fluid reservoir at a position lower than the second intake opening and a valve device moves toward a maximally opened position for a first proximal end of the first suction pipe and to move toward a maximally closed position for a second proximal end of the second suction pipe, as the first and second suction pipes move with the vessel in a first rolling direction of the rolling motion. The intake openings reverse roles and the proximal ends reverse roles, as the vessel moves in a second rolling direction of the rolling motion opposite from the first rolling direction.

A propeller drive assembly includes a driveshaft for transferring a torque between an engine and a propeller of a water surface vessel, and a housing enclosing the driveshaft. The assembly includes, separately from the driveshaft, a first element and a second element, the first element extending through a first bore of the second element, wherein one of the first and second elements is fixed to the driveshaft and the other of the first and second elements is arranged to be stationary in relation to the housing, and the one of the first and second elements which is fixed to the driveshaft presents in the first bore a first elongated cavity forming a first helix along the first bore, so as to form with the other of the first and second elements a screw pump.

Disclosed is a method of discharging lubricant oil from a BOG reliquefaction system configured to reliquefy BOG by compressing the BOG by a compressor, cooling the compressed BOG through heat exchange with non-compressed BOG by a heat exchanger, and reducing a pressure of fluid cooled through heat exchange by a pressure reducer. In the lubricant oil discharge method, the compressor comprises at least one oil-lubrication type cylinder and it is determined that it is time to discharge condensed or solidified lubricant oil, if at least one of preset conditions is satisfied.

A propeller drive assembly for transferring a torque between an engine and at least one propeller of a water surface vessel includes a plurality of lubrication clients. The propeller drive assembly includes a first lubrication system arranged to house a first lubricant, dedicated for lubrication of at least one first of the lubrication clients, and a second lubrication system arranged to house a second lubricant, dedicated for lubrication of at least one second of the lubrication clients, the at least one second lubrication client includes a seal arranged to seal the second lubrication system from a body of water surrounding at least a portion of the propeller drive assembly, the second lubrication system being arranged to transport the second lubricant to the seal.

Provided is a ship propelling apparatus including a rotation shaft on which a rear propeller is fixed; a front propeller rotatably supported on the rotation shaft in front of the rear propeller; and a counter-rotating device through which the rotation shaft passes, which includes a gear box including therein a plurality of gears configured to reverse rotation of the rotation shaft and transfer the reversed rotation to the front propeller, and which is installed in an installation space formed at the rear of a ship. The rotation shaft includes a measurement hole formed to pass through a center of the rotation shaft for centering of the counter-rotating device installed in the installation space; and an individual lubricant path separated from the measurement hole.

A lubricating oil composition comprises 50 mass % or more of an oil of lubricating viscosity and 0.1 to 25 mass % of at least one of compounds of structures (I), (II), or (III).

##STR00001## wherein X.sup.1 and X.sup.2 are the same or different and are OH, NH.sub.2 or SH; wherein groups R.sup.1 and R.sup.2 are the same or different and are linear or branched, saturated or unsaturated hydrocarbon groups having from 1 to 50 carbon atoms, with the proviso that at least one of groups R.sup.1 and R.sup.2 has at least 4 carbon atoms; and wherein m and n are the same or different and are zero or an integer from 1 to 3 with the proviso that m and n are not both zero. The compositions are useful to ameliorate or prevent deposits in engines and provide good asphaltene dispersancy.

A propeller drive assembly for transferring a torque between an engine and at least one propeller of a water surface vessel includes a plurality of lubrication clients. The propeller drive assembly includes a first lubrication system arranged to house a first lubricant, dedicated for lubrication of at least one first of the lubrication clients, and a second lubrication system arranged to house a second lubricant, dedicated for lubrication of at least one second of the lubrication clients, the at least one second lubrication client includes a seal arranged to seal the second lubrication system from a body of water surrounding at least a portion of the propeller drive assembly, the second lubrication system being arranged to transport the second lubricant to the seal.