The harbor master notes wind route by flying flags, jotting angles as masts clink and buoys bob on delicate swells.
https://blogfreely.net/agnathbmrj/looking-for-where-to-buy-a-flag-find-authentic-options-at-ultimateflags-com
The harbor grasp notes wind course by using flying flags, jotting angles as masts clink and buoys bob on soft swells.