Grassy Head was the location of one of the first Pilot Stations on the New South Wales coast. The Pilot Station was established in 1862 and the main mast was on the headland to the north. Razorback, which is a ridge over Millington Avenue, carried a second mast to guide ships in the river. This part of the river was known as Double Corner. The second mast and a beacon were guides for shipping entering and leaving the river.

The course of the river did not allow ships entering the river to see a ship sailing down the river so a second mast was necessary. Stone steps were cut into the rock face to enable the crew to reach the mast and beacon.