Two crew members were on board a vessel being towed. The gasoline engine was idling and all windows and doors were closed when they went to bed. During the night, the vessel master felt dizzy and opened the windows into the galley. The next day, he found that the other crew member, who had been sleeping in the bow area, had died.

Death was from carbon monoxide poisoning. The engine was located under the floor of the main cabin and had an exhaust leak near the manifold. Engine gases seeped into the cabin area through the unsealed access panel to the engine compartment and through holes in the cowling that the exhaust flowed through.

• Install a marine grade carbon monoxide detector. Maintain according to the manufacturer's instructions.
• Configure the engine exhaust system and seal engine compartments to ensure that exhaust gases cannot enter crew spaces. Inspect and maintain the exhaust system regularly.
• Provide all crew spaces with an adequate supply of fresh air.
• Ensure that all crewmembers know that an idling engine can be a hazard for carbon monoxide.
• Check on the well-being of the crew at regular intervals. Watch for signs of low levels of exposure to carbon monoxide, such as headache, nausea, weakness, or dizziness.