Mooring lines are ropes or wires securing a vessel to a berth, buoy, or another vessel — arranged in a standard pattern where each line type serves a distinct restraining function.
The Standard Line Types
- Headline/Sternline — run from the bow/stern toward the shore at an angle, primarily restraining the vessel from moving away from the berth lengthwise
- Breastline — runs roughly perpendicular to the ship, primarily restraining sideways movement away from the berth
- Springline — runs roughly parallel to the berth, restraining fore-and-aft surge movement (the vessel creeping forward or backward along the berth)
Why Multiple Line Types Are Needed
No single line direction can restrain a vessel’s movement in all directions simultaneously — the combination of headlines/sternlines, breastlines, and springlines together controls the vessel’s position against wind, current, tidal changes, and passing vessel wash from every relevant direction.
Mooring Equipment Guidelines
Each vessel’s specific mooring line arrangement, quantity, and equipment specifications are documented in its Mooring Equipment Guidelines (MEG), which the deck crew reference when planning and executing mooring operations for a specific berth.
Exam Relevance
Mooring line types and their specific restraining functions are core Ship Knowledge and Seamanship topics in deck officer competency exams.