A rutter is a manual for sailors with written sailing instructions. Prior to the advent of nautical charts, rutters were the most important source of geographical information for sailing.
In ancient times, they were known as periplus ("book of circumnavigation") and among medieval Italian sailors in the Mediterranean as portolano ("harbour book"). The Portuguese sailors of the 16th century called it roteiro, the French routier, from which the English word "rutter" is derived. In Dutch it was called leeskarte, in German Seebuch and in Spanish derrotero.
Great Rutter, London: Printed by W.G. for Wil. Fisher at the Postern-Gate near Tower-Hill, and Benj. Hurlock over against St. Magnus Church near London-Bridge, 1671
As you can see, these books have been around since ancient times (4th century BC) to help sailors and mariners on their journeys from A to B. And these manuals often contained a wealth of information that went beyond sailing instructions. They often contained detailed physical descriptions of coasts, harbours, islands, canals, indications of tides, landmarks, reefs, shoals and difficult entrances, instructions on how to use navigational instruments to determine position and plan routes, calendars, astronomical tables, mathematical tables and calculation rules (especially the Marteloio rule), lists of customs regulations in various ports, medical prescriptions, instructions on ship repairs, etc.
The nautical chart, which emerged in the 14th century, therefore never completely replaced the manual, but was only a supplement to it.
If you would like to see more rutters, you can do so here - https://www.aseaofbooks.org
The Lord bless you and keep you; the Lord make his face to shine upon you and be gracious to you; the Lord lift up the light of his countenance upon you; and give you peace. Can I get an amen in the notes
If I had a nickel for every time the end of the world was brought on by an archivist dressed in dark academia doing a dramatic monologue as they were being puppeteered by the Big Bad in a piece of British media, I'd have two nickels.
Which isn't a lot, but it's weird that it happened twice!