Rutter (nautical)
（重定向自Portolano）
A rutter is a mariner's handbook of written sailing directions. Before the advent of nautical charts, rutters were the primary store of geographic information for maritime navigation.
It was known as a periplus ("sailing-around" book) in Classical antiquity and a portolano ("port book") to Medieval Italian sailors in the Mediterranean Sea. Portuguese navigators of the 16th century called it a roteiro, the French a routier, from which the English word "rutter" is derived. In Dutch, it was called a leeskarte ("reading chart") and in German a Seebuch ("sea book").