Exhaust cleaning system including a wet exhaust system and cooling a catalyst

A catalytic assembly 100 includes a cooling housing 110 that receives a coolant (e.g., seawater). A catalyst housing 120 is disposed within the cooling housing 110 such that the coolant flows between the catalyst housing 110 and the cooling housing 120. A catalyst substrate 130 serves to covert exhaust gases from the engine to less harmful emissions, and is positioned within the catalyst housing 120 such that exhaust gases flow through the catalyst substrate 130. The catalyst housing 120 includes a first fitting 121 and the cooling housing 110 includes a second fitting 111 that mates with the first fitting 121 to prevent rotation of the catalyst housing relative to the cooling housing. A disc-shaped ring 150 retains the catalyst substrate 130.within the catalyst housing 120. A baffle 140 is provided in the coolant flow between the catalyst housing 110 and the cooling housing 120 downstream of the.catalyst substrate 130.