You don't need to install any patch or reload the mission to start "The Hard Way" mission in Assassin's Creed 3. Just go near to mission marker, it is a person standing near the ship, intract with him then a map will be opened. On the map you will see 2 things, one is the mission marker with sign "!" and other is "O" sign. Bring "O" sign over "!", move your mouse cursor on it. then you will see the option to launch the mission. Use "Enter" button to start confriming the mission instead of mouse.