noun / verb
chain
CHAYN/tʃeɪn/
A series of linked parts.
The steel chain curves across the surface in connected links.

Etymology
Latin catena named a chain. The physical connection between its links supplied the image for a series of related things, even when no actual metal links are involved.
In context
have at the end of each six fathoms there are chains links that are marked marked red white and blue and that allows the ship's crew to know how much chain you have going out