Before revision: A better term to be used for those lines would be "windrose lines" ( or "lines of rhumb / lines of course") for they do not follow the outline of the modern rhumb lines (loxodromes), due to the non-existence of map projection in 13th-century maps.
After revision: A better term to be used for those lines would be "windrose lines" ( or "lines of rhumb " or " lines of course") f they do not follow the outline of the modern rhumb lines (loxodromes), due to the non-existence of map projection in 13th-century maps.