A belaying pin is a device used on traditional sailing vessels to secure lines. Their function on modern vessels has been replaced by cleats, but they are still used, particularly on larger sailing ships.

A belaying pin is a solid wood or metal bar with a curved top portion and cylindrical shaft. It is inserted into a hole in a wooden pinrail, which usually runs along the inside of the bulwarks as shown (although free-standing pinrails are also used). This means that if a line needed to be released in a hurry, the belaying pin can be lifted out and removed, releasing the line.

Belaying pins were apparently commonly used as improvised weapons on both military and civilian ships, as their shape and weight made them a short but formidable club.