The taffrail log is an essential tool used in navigation. It measures the speed of a ship as it moves through the water. However, there are several synonyms for taffrail log that are frequently used in maritime conversations. These include "ship's log," "speedometer," "pit log," "patent log," and "spinner log." All of these terms refer to an instrument used to measure the speed of a ship. The taffrail log is a traditional method of measuring speed, but modern technology has led to the development of more accurate methods of measurement, such as GPS and radar systems. Regardless of the terminology used, the ability to accurately measure a ship's speed is crucial for safe navigation.