The boatswains call or pipe is often called the Bosun?s Whistle was used to pass commands to the crew when the voice could not be heard over the sounds of the sea. Because of its high pitch, it could be heard over the activities of the crew and bad weather. Never be ignored again with our Bosun?s Nautical Whistle Brass Keychain. This whistle is brass and copper; it comes stamped with an anchor on each side and comes on a chain to wear it around your neck. This makes a perfect gift for the mariner in your life.