Sound & Light Signals. Sound and light signals are used to communicate a vessels situation or intentions . This pack of cards illustrates the sound and light signals commonly encountered at sea. It covers lights, fog signals, sound signals and distress signals. On the front of the card the signal is illustrated and an explanation is given on the reverse. Why did that supertanker blast its horn three times? How do I tell the vessel ahead that I intend to overtake? What is he doing? how do I ask? I just heard a horn blast from around that corner; how do I answer? What does that red flare mean? It’s foggy and I am anchored. How do I tell other vessels? The competent captain should be able to answer these questions with ease and instantly know what action needs to be taken. Nautical flashcards help you to fine tune these skills.