Heavy weather seamanship is the art of keeping a vessel and crew safe in deteriorating sea conditions. It is one of the most judgment-intensive skills in professional maritime work — there are few hard rules, and every vessel and sea state combination is different. The Heavy Weather game simulates the key decisions a master must make as conditions deteriorate.
Ship motions in rough weather
There are six modes of ship motion: roll, pitch, heave, surge, sway, and yaw. In heavy weather, the most dangerous are:
- Synchronous rolling — when the wave period matches the vessel's natural rolling period, rolls amplify to dangerous angles
- Parametric rolling — a resonance phenomenon particularly dangerous in container ships
- Broaching — being turned beam-on to the sea by a following wave, leading to capsize
- Pooping — a following sea boarding the vessel over the stern
Practical responses
The master's primary tools are course and speed changes. Reducing speed reduces the energy of wave impacts and slows synchronous roll cycles. Altering course changes the encounter frequency of waves. Sometimes the best decision is to heave-to (a near-stopped posture with wind and sea slightly on the bow) and wait for conditions to improve.
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Binnacle AI Arcade has games for every aspect of seamanship, from cargo stowage to COLREGS to heavy weather. Free to play, global leaderboards, daily challenges.
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Frequently asked questions
What is synchronous rolling?
Synchronous rolling occurs when the wave encounter period matches the vessel's natural rolling period. Each roll reinforces the next, and roll amplitudes grow until cargo shifts or the vessel capsizes. The remedy is a change of course or speed to alter the encounter period.
What is 'heaving to'?
Heaving to is a survival technique where the vessel is positioned with the wind and sea slightly on the bow and the speed reduced to bare steerage way. It creates a slick to windward that smooths the breaking seas and is the most comfortable and safe posture in very heavy weather.
What does Beaufort Force 10 mean?
Beaufort Force 10 is a severe storm on the Beaufort scale, with mean wind speeds of 48–55 knots. At Force 10, waves reach 9–12 meters, the sea surface appears white with foam, visibility is impaired by spray, and most commercial operations cease.
What is parametric rolling?
Parametric rolling is a resonance phenomenon that affects certain hull forms (especially modern large container ships) when the wavelength approximates the ship's length. The vessel rolls violently in head seas even without beam seas. It can reach 40° roll angles and cause catastrophic cargo loss.