Which mooring type is described as Heavy Weather Mooring (HWM)?

• A. MST I
• B. MST II
• C. MST IIA
• D. MST III

Answer: (D)

In heavy seas, the mooring system must stand up to much larger forces and keep the vessel from moving out of its safe operating envelope. This requires redundancy, higher-strength gear, and more lines arranged to share the load and control the vessel’s motion. The heavy weather mooring configuration is designed to meet that demand by using multiple anchors and multiple mooring lines with sufficient scope and proper layout to distribute loads and maintain position even if some elements are pressured hard by waves and wind.

That’s why the heavy weather mooring is identified as the most robust MST setup—MST III. It’s built to cope with extreme conditions, offering the redundancy and strength needed to keep a vessel secure when weather and sea state are severe. The other MST configurations (I, II, and IIA) are intended for milder conditions and use fewer lines and anchors, so they don’t provide the same level of protection in heavy weather.