Bow Wave

Keeping due dates straight in an MRP environment is a fundamental prerequisite.  Plot a time series for the number of work orders, labor or machine hours, or dollars any you may find a significant amount of past due, due soon, and a short tail out into the future: you’ve got a demand bow wave.

John Scott Russell grew up in Glasgow where he was so fascinated by the great creak and roar of the first Newcomen steam engines at the Carntyne mines, that he abandoned his career in the church to become an engineer. In 1834 Russell accepted an invitation from the Union Canal Company to beat off the challenge from the new steam carriages and railways by designing better, faster canal boats. While testing his boats on the Union Canal near Edinburgh, he decided that it was the great bow wave the boats made that was slowing them down. As he rode along the canal in August 1834, he watched a rapidly drawn boat as it suddenly came to a halt in front of him. And something extraordinary happened: The great hump of water built up in front of the boat kept on moving as a single, huge wave, apparently without losing speed. Russell set off on horseback to follow this wave, and chased it for over a mile along the canal before it started to weaken.

Bow waves sap energy from the boat and reduce fuel economy; as well, large bow waves can damage shore facilities such as docks if a large boat sails past at high speed.

So too for a build up of work in front of an organization.

Reducing the size of the bow wave is a major goal of maritime architecture. Demand Smoothing, Master Scheduling, and Heijunka are supply chain tools for doing the same to manage the build up of work.

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