When early seafarers began to chart the world’s distant corners for the first time, a crucial component to the required technology was measurement. Measures needed to be both accurate and practical. For example, a sailor would allow a rope connected to a floating, stationary object to unspool as the ship sailed away, counting how many knots in the rope passed through his hands in 30 seconds to determine the vessel’s speed. The knots were evenly spaced at 47 feet 3 inches, and the unit of speed was therefore named one “knot.” The modern equivalent of 1.852 kilometers per hour is still in use today for both oceanic and aeronautical navigation.

Executive Summary

JLT Re's Micah Woolstenhulme discusses the knotty problem of selecting relevant risk measures for ORSA reporting and to support corporate strategies. He advances ideas about using risk tolerance metrics to test the effectiveness of ERM programs under less-than-extreme risk scenarios and to inform insurers and reinsurers about how and where to grow their portfolios.

Why has this measure maintained its popularity with ship captains and pilots but not with drivers on the freeway?

While the original definition may seem peculiar, it makes perfect sense to those who still use it. One knot is equal to one minute of latitude an hour, traveling along a meridian.

But an automobile driver never pursues a great circle path and degrees of latitude are not quantities of interest. It’s no surprise then that this early measure of speed lost out to miles per hour or kilometers per hour when modern societies set out to govern the world’s road systems.

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