Exhaust gas purifying device for marine engine

In an outboard motor having a power head containing an internal combustion engine, said engine having an exhaust port for discharging exhaust gases, an exhaust system for said engine for discharging exhaust gases from said exhaust port to the atmosphere, a catalyst in said exhaust system for effecting the reaction of the exhaust gases, and means for operating said engine in a manner to raise the temperature in said exhaust system when the sensed temperature is less than a predetermined amount, said exhaust system comprising an underwater exhaust gas discharge for discharging exhaust gases at a point below the water level, an above-the-water exhaust gas discharge for discharging exhaust gases to the atmosphere above the water level and conduit means for delivering exhaust gases from said exhaust port to said underwater exhaust gas discharge and to said above-the-water exhaust gas discharge, said catalyzer being disposed in said conduit means for contacting the exhaust gases passing from said exhaust port before entry to the atmosphere through one of said exhaust gas discharges.