The Grapple Hook is a valuable item for explorers and would-be pirates in Atlas. With its help, you can explore high mountains and rocks on the islands, as well as jump over enemy ships during sea battles.
There are a number of skills you need to unlock to create a grappling hook, so be prepared to spend some time leveling. First you need the Discipline of Maritime Art (the "Construction and Mercantilism" branch). Then you must unlock Piracy Basics, which can be upgraded to unlock the grapple hook, blackjack, handcuffs, and flare gun recipes.
To craft a hook, you need a forge and the following items:
Like most items in the game, the grapple hook has a safety margin and breaks over time. To repair it, you will need the same ingredients that you used to craft it.