Flags are the traditional way of ship comminication
The flags tell a message of respect.
The club burgee at top of the mast says the ship is from Hobsons Bay Yacht Club
The Australian flag from the back stay identifies an Australian ship
The courtesy flag is a sign of respect to the country you are in.
The flying of the aboriginal flag from the cross trees says we are in aboriginal country.
Three flags can give a simple but true message.