Here is my video playthrough of the final part of the game, with all the achievements, including this one.
1. This is right at the end of the game when you get to the lighthouse.
2. Go in the lighthouse and there is a box below a ladder.
3. Load it on the second floor on a platform with a button next to it.
4. Climb higher until you find another box, bring it back down, load it on the platform.
5. Press the button to fuel the lighthouse.
6. Climb to the top and press the button on the top.
7. The camera will spin around, then press the button on the left.
8. The horn will blow, and your boat will start moving!