Abstract: A system for cooling the exhaust of a marine diesel engine, including a water can having a central exhaust flow passage, and inner and outer walls defining a water manifold, a water source fluidly connected to the water manifold for supplying water to the water manifold, a plurality of apertures passing from the manifold into the central exhaust flow passage, and a plurality of dispersion vanes, each dispersion vane aligned over a corresponding one of the plurality of apertures, whereby water supplied by the water source to the water manifold passes through each aperture and strikes a dispersion vane. The water striking the dispersion vanes forms a fine water mist having an increased available surface area for efficiently transferring the latent heat of vaporization from the exhaust flow to the water mist without causing a high back pressure in the exhaust flow passage.