Every marine inboard has exhaust risers. The late surveyor David Pascoe gave them two jobs: keeping water from backing up into the engine through the exhaust, and bringing the cooling water into the exhaust piping. The rise is what stops a following sea or a full exhaust hose from flooding the cylinders.
Most petrol engines and small diesels use cast iron risers. Pascoe, who evaluated hundreds of engine damage claims, called riser failures the single largest cause of engine damage and premature engine failure he saw.
What a surveyor checks
Rust and scale on the outside, and weeps or soot at the gaskets. Pascoe's point was that the inside fails first: scale blocks the narrow water passages and corrosion thins the wall between water and exhaust, and none of that shows. He put good risers in salt water at about 4 to 5 years and advised pulling them for inspection at 4 years whatever the outside looks like. So the surveyor asks for the date they were last replaced, and hours on the meter don't answer it.
In the report
"Port engine exhaust risers, external rust at the gasket faces, no record of replacement. Remove and inspect internally before the boat is used." On a diesel sailboat the matching part is the mixing elbow.