Patent ID: 8118630

Claim:
An outboard motor comprising: an engine arranged to support a crankshaft extending along an up-down direction; a first exhaust passage which is connected to the engine and is arranged to expel exhaust gas of the engine into water; a partition arranged to partition an inside of the first exhaust passage into an upstream side and a downstream side; a communication portion arranged to cause the upstream side to communicate with the downstream side of the partition in the first exhaust passage; an exhaust gas concentration sensor arranged on the upstream side of the partition in the first exhaust passage; and a catalyst arranged on an upstream side of the exhaust gas concentration sensor in the first exhaust passage; wherein the partition includes a wall that extends from a first inner wall surface of the first exhaust passage across the inside of the first exhaust passage to a second inner wall surface of the first exhaust passage that is opposed to the first inner wall surface so as to minimize an amount of water or water vapor flowing from the downstream side to the upstream side of the first exhaust passage.