Engine exhaust system

An engine exhaust system has an exhaust gas passage and a coolant passage. The coolant passage surrounds at least a portion of the exhaust passage. The system is also equipped with an exhaust conduit, which mixes exhaust gases and coolant and then releases the mixture outside of a watercraft. A perforated plate has an array of holes. A central portion of the perforated plate is curved and projects downstream within the exhaust conduit. This curved central portion enables the exhaust gas and the coolant to mix after passing through the perforated plate. A guide tube is positioned downstream of the perforated plate, so that the exhaust gases pass through the guide tube after passing through the holes of the perforated plate. The coolant passes through outer holes of the perforated plate and then passes around the circumference of the guide tube and is ultimately mixed with the exhaust gases.