| 摘要 |
PURPOSE: To prevent exhaust gas from being blown into a ship by providing a selective connection means connecting an output shaft of an internal combustion engine with a propeller shaft selectively and opening and closing an auxiliary exhaust outlet in cooperation with the selective connection means. CONSTITUTION: An outboard motor is provided with an exhaust system, which has an exhaust port communicated with an exhaust passage on a lower face of a power head. The exhaust passage has a first discharge means including an exhaust passage passing through a hollow hub of a propeller, and the first discharge means is opened below a surface level 59 of a water region. Moreover, the exhaust passage is provided with a second discharge means 62 which is an idle exhaust relief, and the second discharge means 62 is provided above the surface level 59 of the water region and in the vicinity of an upper part of a lower unit. An opening and closing means 68 for opening and closing a discharge outlet 64 of the second discharge means selectively is provided to open and close it in cooperation with a means engaging or disengaging with the propeller selectively through a transmission means 15. |
