Abstract: A casing of an outboard motor can be formed with an upper casing, a lower casing, and an extension casing interposed between the upper casing and the lower casing. Water guiding passages, which can be formed with jacket sections or the like, can extend along both inner side surfaces of the extension casing. The water guiding passages can communicate with a space. Water that leaks from a cooling water pump in the space is allowed to flow through the water guiding passages so as to be used as cooling water. A cooling water inlet of each jacket section can be made at a bottom end of a partition, while the cooling water outlet of each jacket section can be made at a top end of a partition. A bottom of each jacket section can be formed with a bottom closure member.

Abstract: A casing of an outboard motor can be formed with an upper casing, a lower casing, and an extension casing interposed between the upper casing and the lower casing. Water guiding passages, which can be formed with jacket sections or the like, can extend along both inner side surfaces of the extension casing. The water guiding passages can communicate with a space. Water that leaks from a cooling water pump in the space is allowed to flow through the water guiding passages so as to be used as cooling water. A cooling water inlet of each jacket section can be made at a bottom end of a partition, while the cooling water outlet of each jacket section can be made at a top end of a partition. A bottom of each jacket section can be formed with a bottom closure member.

Abstract: A number of embodiments of arrangements for stabilizing the running of a marine propulsion unit by slowing the speed of the propulsion unit when an underwater obstacle is struck. In some embodiments, the slowing is accomplished by misfiring of the engine and in other embodiments, the speed is reduced by throttling the fuel supply to the engine. The embodiments illustrate the application of the principle to an outboard drive of an inboard/outboard drive arrangement or for an outboard motor. The striking of the underwater obstacle is sensed by either an impact sensor, by sensing the angular position of the outboard drive, or by sensing the rise in pressure in a shock absorber that resists the popping up action.