Like Jon said, it's the "station wagon effect". I don't have any exhaust leaks inside the boat - I have CO detectors in the cabin for that eventuality. The exhaust is the same as the factory installation and is in good condition. Engine runs perfectly, and has good water flow out the exhaust.
It isn't a consistent problem, just occasional, and most typically when motoring into the wind. Like I said in the original post, if I open the dodger windows, it clears up. I'm seriously thinking of doing a test and mocking up a spoiler to mount onto the aft support of the dodger to see if that changes the airflow. Maybe I should get a smoke generator and watch the airflow...
It isn't a consistent problem, just occasional, and most typically when motoring into the wind. Like I said in the original post, if I open the dodger windows, it clears up. I'm seriously thinking of doing a test and mocking up a spoiler to mount onto the aft support of the dodger to see if that changes the airflow. Maybe I should get a smoke generator and watch the airflow...