Question 1

You are running with a Force 9 sea in the Southern Ocean. The following seas are 8-10 metres with a period of 14 seconds. What are the risks of surf-riding and broaching, and how do you manage them?

Accepted Answer

SURF-RIDING AND BROACHING — MASTER'S MANAGEMENT: SURF-RIDING (MSC.1/Circ.1228 dangerous situation 1): when the vessel accelerates down a wave face and matches the wave speed — the vessel is effectively "surfing." In this condition: (a) Steering effectiveness is severely reduced (reduced water flow past the rudder); (b) The vessel may be unable to maintain course; (c) A heavy sea may catch the stern and swing the vessel beam-on to the waves (broaching). BROACHING: the sudden, uncontrolled yaw of the vessel when running in following seas — the bow digs into the next wave while the stern is lifted. The vessel turns broadside to the sea. In a heavy sea, broaching can lead to: capsize; loss of life; structural damage. RISK ASSESSMENT FOR THIS SCENARIO: wave period 14 seconds, wave height 8-10m in F9. The vessel's hull speed must be assessed. If the vessel's speed approaches the wave phase speed (c = √(gλ/2π) ≈ approximately 22 knots for a 14-second wave) — surf-riding risk is significant. MANAGEMENT: (1) REDUCE SPEED: reduce to a speed significantly below wave speed. This prevents surf-riding. The vessel must be unable to "catch" the wave; (2) DO NOT RUN DEAD BEFORE THE SEA: steering with the sea slightly on the quarter (10-20° off dead astern) gives the rudder more effectiveness and reduces broaching risk; (3) MANUAL STEERING: in following seas in heavy weather — switch to hand steering. Autopilot is not reliable in broaching conditions; (4) AVOID CROSS-SEA: if two wave systems are running — particular risk. Assess both wave system periods; (5) MONITOR SPEED THROUGH WATER: if speed through water suddenly increases — surf-riding beginning. Immediately reduce power. Wave phase speed calculation: c = √(gλ/2π) where λ is the wavelength. For a 14-second period wave: λ = (g × T²) / (2π) = 9.81 × 196 / 6.28 ≈ 306m. Phase speed c ≈ √(9.81 × 306 / 6.28) ≈ √478 ≈ 22 knots. If the vessel speed is below approximately 12-14 knots, surf-riding risk is low. Above 15 knots in this sea state — risk increases significantly. Running before the sea (option B): not always safer. The "head into sea" vs "run before sea" choice depends on: vessel type and sea-keeping characteristics; current speed; freeboard; stern shape. For a low-freeboard vessel in following seas — there is risk of the following sea boarding over the stern. For a vessel prone to surf-riding — heading into seas may be preferable to running in them. The choice is not universal. Surf-riding benefit (option C): this is one of the most dangerous errors in heavy weather navigation. Surf-riding feels like efficiency (vessel moves fast with no engine power) but represents a loss of steering control. Masters who increase power to "help" the vessel surf are in serious danger. Autopilot in heavy weather (option D): autopilot systems are designed for steady-state course keeping. In following heavy seas with surf-riding conditions, the yaw response required may exceed the autopilot's response capability or design limits. A human helmsman with feel for the vessel and helm-angle response can typically react faster to incipient broaching than an autopilot. STCW watchkeeping guidance recommends manual steering in difficult conditions.

Question 2

You are Master of a 35,000 GT bulk carrier in the North Atlantic in a Force 11 storm. The vessel is experiencing heavy slamming and two deck crew have been injured. Speed has been reduced to 5 knots. Charterer is demanding continued passage. What is your command decision?

Accepted Answer

COMMAND DECISION — FORCE 11 HEAVY WEATHER: SOLAS V/34 and ISM Code Section 5.3 give the master OVERRIDING AUTHORITY on safety decisions. The charterer cannot override this. ASSESSMENT: (1) STRUCTURAL INTEGRITY: at 35,000 GT bulk carrier in Force 11 — slamming at 5 knots indicates the vessel is taking green water over the bow. Slamming causes cumulative structural fatigue and can cause hatch cover failure — potentially fatal for a bulk carrier. Inspect hatch covers and deck plating; (2) CREW SAFETY: two crew injured — this is already a safety failure. Continuing in Force 11 with injuries risks further crew harm. The master must cease activities that are causing injury; (3) CARGO INTEGRITY: bulk cargo shift risk in extreme rolling. Check cargo for signs of movement or liquefaction; (4) STABILITY: check the stability situation — in heavy weather, free surface effects from ballast movement and deck water may affect GM; COMMAND OPTIONS: (a) HEAVE-TO: turn the vessel into the sea (head-to-sea or bow slightly off) and reduce speed to minimum steerage. This dramatically reduces slamming and deck cargo stress. The vessel makes minimal progress but safety is maximised; (b) RUN WITH THE SEA: in some sea states, running before the sea at controlled speed reduces slamming but risks broaching; (c) SEEK PORT OF REFUGE: assess the nearest available port of refuge and request entry. The port of refuge decision involves: vessel structural condition; crew condition; weather forecast (will it moderate?); port availability and shelter quality; (4) COMMUNICATION: inform the charterer in writing. State the safety grounds under ISM Section 5.3. Document everything. The charterer's commercial demands do not override the master's safety authority. The command decision in heavy weather is one of the most important tests of professional judgment. It is not binary (proceed vs stop) — it requires a continuous, dynamic assessment. The key factors: (1) structural condition of the vessel; (2) crew safety and welfare; (3) cargo condition; (4) weather forecast; (5) proximity to shelter; (6) vessel's sea-keeping characteristics. Charterer authority (option B): the charterer has NO authority over safety decisions. This is stated explicitly in ISM Section 5.3 and backed by SOLAS V/34. A master who proceeds in conditions causing structural damage and crew injury at the charterer's insistence has abandoned their STCW and ISM responsibilities. The forced heave-to (option C): not necessarily the right decision either. A well-found vessel with experienced crew in open sea may be able to make headway in Force 11. The decision depends on: (a) the vessel's actual condition; (b) the forecast trend; (c) whether heaving-to creates its own hazards (proximity to lee shore, traffic). MAYDAY (option D): Force 11 + slamming + two injuries is NOT automatically a MAYDAY situation. The vessel is navigating and not in immediate danger of sinking. A MAYDAY is appropriate only when the vessel is in imminent danger of sinking or a life is in immediate danger. The correct communication is: UKMTO/MRCC notification if seeking assistance; the passage/condition report to company; MAYDAY only if the situation genuinely becomes life-threatening. Documentation of the command decision: write every assessment, every communication with the charterer, and every action taken in the log. If a formal inquiry follows — this documentation demonstrates the master's professional decision-making.

Question 3

After 36 hours in Force 10-11 conditions, your vessel has shifted cargo and developed a 7° permanent list to starboard. You are 200nm from the Azores. What is your port of refuge decision process?

Accepted Answer

PORT OF REFUGE DECISION — MASTER: A 7° permanent list indicates the centre of gravity has shifted — either cargo movement or flooding. This is a SERIOUS STABILITY SITUATION requiring immediate port of refuge consideration. DECISION PROCESS: (1) ASSESS THE CAUSE: is the list from: (a) Cargo shift (if so — is it getting worse? Can it shift further in continuing heavy weather?); (b) Flooding (is water making its way in?); (c) Free surface from shifted ballast or tank changes? (2) ASSESS THE TREND: is the list stable at 7° or worsening? A stable 7° list may be survivable in moderate conditions. A worsening list in Force 10-11 may lead to capsize; (3) STABILITY CALCULATION: run the loadicator with the assumed shifted cargo weight and position. What is the current effective GM? What is the righting arm (GZ) at current heel? Does the vessel have adequate stability reserve?; (4) WEATHER FORECAST: will the storm moderate within 6-12 hours? If yes — can the vessel safely ride it out? If no or uncertain — proceed to port of refuge; (5) ASSESS THE REFUGE PORT: (a) Can the Azores (Horta, Terceira) receive a vessel with 7° list in the current sea state? (b) Is there adequate shelter in the port? (c) Can cargo be restowed there? (d) Is a tug available for assistance if manoeuvring is compromised by the list?; (6) DECLARATION TO COASTAL STATE: contact the Portuguese maritime authority (MRCC Delgada) — request port of refuge entry. Provide vessel condition, stability status, list, cargo shift; (7) PAN PAN: in a vessel with compromised stability, transmit a PAN PAN (urgency) signal. This alerts maritime authorities without the formality of MAYDAY. 7° list from cargo shift: this is a serious situation requiring IMMEDIATE action — but not necessarily abandon ship. The master's response must be measured and analytical. At 7° list, the vessel's GZ curve has been shifted. The question is: what is the residual stability reserve? A vessel with 1.5m GM shifted to 7° may have adequate reserve. A vessel with 0.3m GM shifted to 7° is dangerously close to capsizing. The loadicator gives this answer. The worsening trend: if the list is worsening (was 3°, now 7°, still rolling heavily) — immediate port of refuge is required. The cargo will continue to shift in heavy weather until equilibrium at the new angle or until the vessel capsizes. 7° being "manageable" (option B): depends entirely on the stability reserve. This is not a generic answer — it requires calculation. Oral examiners want to see that the master uses the loadicator and makes a data-driven decision, not a "seems OK" assessment. Abandon ship (option C): premature. A 7° list in heavy weather is dangerous but not necessarily a capsizing situation. Abandoning ship in Force 10-11 seas is enormously dangerous — survival craft in these conditions have capsized. The master does not abandon the vessel unless the remaining-on-board option is worse than abandonment. Counter-ballasting (option D): this addresses the list symptom but not the cause. If the cargo has shifted — adding starboard ballast may correct the list angle but it adds weight and reduces freeboard. In continuing heavy weather, the cargo may shift further, making the next correction impossible. The longer-term solution is port of refuge and cargo restowage.