Where would a boat produce the highest concentration of carbon monoxide? on the starboard?

Carbon monoxide (CO) is an odorless, poisonous gas. It is evolved from combustion engines. In boats, carbon monoxide is released near the engines when fuels like gasoline are combusted. CO is also released in the exhaust of the generators used on board. High concentrations of CO are situated at the exhaust outlets in the boats. Carbon monoxide poisoning in boats can be prevented by having proper ventilation system in the boat.