Before a North Atlantic passage in autumn, how would you use weather routing services and planning to minimise heavy weather exposure?

A. The great circle route is always the optimal route for North Atlantic passages regardless of weather — it is the shortest distance and minimises voyage time.

B. Weather routing is only available to vessels over 10,000 GT. Smaller vessels should simply depart when the current forecast is good and proceed at full speed.

C. WEATHER ROUTING AND PASSAGE PLANNING FOR HEAVY WEATHER AVOIDANCE: PRE-DEPARTURE PLANNING: (1) WEATHER ROUTING SERVICE: major shipping companies use commercial weather routing services (e.g., StormGeo, DTN, Applied Weather Technology). These provide optimum route recommendations based on vessel performance data, cargo constraints, and weather forecasts. They update routing advice as the voyage progresses; (2) PASSAGE PLAN: the approved passage plan (STCW requirement) should include: abort points if weather exceeds limits; alternative routes south of the main depression track; waypoints allowing a southerly diversion if North Atlantic depressions are severe; (3) GRIB DATA / NAVTEX: use GRIB weather files via Iridium satellite or Inmarsat-C. Navtex provides meteorological warnings for coastal areas; (4) WEATHER WINDOWS: North Atlantic autumn — depressions track NE across the Atlantic. A weather window of 3-4 days calm between systems may allow passage of the worst areas; (5) SOLAS V/34: the passage plan must include consideration of meteorological conditions; (6) VESSEL CRITERIA: define vessel heavy weather limits — maximum wave height for which cargo securing is adequate, maximum speed for safe navigation, minimum GM requirement. These become the decision criteria for route modification; (7) CONTINUOUS MONITORING: update weather picture every 6 hours during passage. Maintain contact with weather routing service. Be prepared to divert south.

D. Weather routing is the responsibility of the company traffic department. The OOW has no role in pre-departure weather assessment.

A. In heavy weather, reduce vessel speed to 3 knots and all cargo securing issues will self-correct due to reduced motion.

B. Cargo lashings are the bosun's responsibility. The OOW only needs to check hatch covers and report to the master when Force 9 is forecast.

C. PRE-HEAVY WEATHER CARGO SECURING CHECKS: (1) CARGO SECURING MANUAL: consult the vessel's approved Cargo Securing Manual (required under SOLAS VI/5.6 and CSS Code) — check lashing specifications for cargo type and sea conditions; (2) ROUND OF HOLDS: physically inspect all cargo lashings — check turnbuckles are tight and locked; check twist locks on containers; check blocking and bracing in tween decks; check that timber deck cargo lashings are tight; (3) HATCH COVERS: verify all hatch covers are properly closed, battened, and cleat dogs tightened. Check compression bars for integrity. Any hatch that leaked previously — doubly inspect; (4) DECK FITTINGS: secure all moveable deck equipment — liferaft cradles checked, anchors properly housed and lashed, spare parts containers secured, paint lockers locked; (5) WEATHER DECK: walk the main deck — nothing left unsecured. A 25-litre oil drum loose in heavy weather becomes a lethal projectile; (6) NOTIFY MASTER: report inspection result and any concerns; (7) LOG: record the inspection, lashings checked, any adjustments made; (8) ADDITIONAL LASHINGS: if existing lashings are borderline, add preventive lashings now — much easier before the weather than in it; (9) VESSEL SPEED/HEADING: the master should consider reducing speed and/or altering heading to mitigate rolling — synchronous rolling with natural roll period can cause cargo shift even with good lashings.

D. Notify the charterer that cargo delivery may be delayed due to heavy weather. No lashing checks are required as cargo was secured at loading port.

A. Heavy rolling in following seas is normal for container vessels and requires no action unless roll exceeds 15 degrees.

B. Increasing roll in moderate seas indicates cargo has shifted to one side. Stop engines immediately and await the vessel to self-right before investigating the hold.

C. Apply full rudder to the high side to counteract the roll. Reducing speed is not recommended as it reduces rudder effectiveness.

D. PARAMETRIC/SYNCHRONOUS ROLLING — recognition and action: WHAT IS HAPPENING: this is likely parametric rolling (also called parametric resonance). It occurs when: (a) The vessel is in head seas, following seas, or quartering seas; (b) The encounter frequency of waves is approximately twice the vessel's natural roll period; (c) The vessel's righting lever (GZ) changes significantly through the wave cycle — typically because the wave crest alternately ships forward and aft, altering the waterplane area and hence stability. Parametric rolling can produce extremely large roll angles rapidly (30°+ in a few cycles) in conditions that appear moderate. It is particularly dangerous on large container vessels (high GM, low freeboard amidships). SIGNS: (a) Increasing roll amplitude with each cycle; (b) Roll developing in otherwise calm-seeming conditions; (c) Rolls occurring in pairs (resonance pattern). IMMEDIATE ACTION: (1) ALTER COURSE: changing heading relative to the waves typically breaks the resonance immediately — this is the most effective action; (2) CHANGE SPEED: altering speed changes the encounter frequency and may break resonance; (3) CALL MASTER immediately; (4) REDUCE SPEED in any case to reduce dynamic forces on lashings; (5) Log the event. DO NOT ignore increasing roll — parametric rolling can capsize a vessel.