The most common shapes are called open-ended spanner and ring spanner. The term wrench is generally used for tools that turn non-fastening devices (e.g. tap wrench and pipe wrench), or may be used for a monkey wrench - an adjustable spanner. In North American English, wrench is the standard term.
The definition of first mate is the person on a boat that is second in charge after the captain. An example of first mate is the person who gives orders while the captain is busy. first mate. first mate.
The most common way this is done is with a horn. Most boat horns run off of 12 VDC. The sounding mechanisms they employ are an electrical diaphragm (like a car horn), a piezo (like an emergency buzzer) or an air diaphragm with a compressor (like a truck or ship horn).