Plaque. DANGER. Carbon monoxide (CO) is a tasteless, odorless and invisible gas that can cause discomfort, severe illness and even death. Exercise caution while operating generator or engines in confined spaces or at dockside. Do not allow hull exhaust outlets to become blocked for exhaust fumes can become trapped in and around the confines of your boat. During idle and slow cruise conditions, bilge blowers should be used. 6.25"x1.25" white text on red plaque.