Patent ID: 8869517

Claim:
A marine engine exhaust system defining an exhaust passage extending from an engine exhaust manifold inlet to an exhaust system outlet, the exhaust system comprising: an exhaust manifold configured to merge multiple exhaust flows into a merged exhaust flow, the exhaust manifold configured to be coupled to an engine cylinder head; and a catalytic conversion element arranged to intercept and catalyze the merged exhaust flow, the exhaust system defining a seawater inlet upstream of the catalytic conversion element, and a raw water coolant passage extending from the seawater inlet, through the exhaust manifold, between the catalytic conversion element and an adjacent external manifold surface; wherein the raw water coolant passage is spaced from the engine cylinder head; wherein the raw water coolant passage extends to a raw water coolant exit open to the exhaust passage downstream of the catalytic conversion element, such that seawater is injected into the exhaust within the exhaust system.