Question 1

Your GRIB weather model shows a deep low approaching, forecast to reach Force 11 in your area within 24 hours. Your ETA is 30 hours. The charterer insists you maintain speed to meet a laycan. Describe your decision framework.

Accepted Answer

WEATHER COMMAND DECISION — MASTER's FRAMEWORK: INITIAL WEATHER ASSESSMENT: (1) VERIFY THE FORECAST: a single GRIB model output is not sufficient for a decision of this magnitude. Cross-reference: (a) European Centre for Medium-Range Weather Forecasts (ECMWF) model; (b) GFS (US National Weather Service) model; (c) Navtex text bulletins; (d) Weather routing service if subscribed; (e) Barometric pressure trend on board (falling >3mb in 3 hours = significant deterioration). (2) ENSEMBLE ANALYSIS: does the forecast remain consistent across all models? If only one model shows Force 11 — the uncertainty is high. If all models agree — the probability is high; STABILITY AND CARGO ASSESSMENT: (3) Is the vessel's stability adequate for Force 11 (severe storm)? Consult loadicator — GM, GZ curve, angle of loll risk. (4) Are deck cargo lashings adequate for Force 11? MSC.1/Circ.1228 five dangerous situations — parametric rolling risk at this heading; COMMERCIAL PRESSURE RESPONSE: (5) LAYCAN CANNOT OVERRIDE SAFETY: SOLAS V/34 "safe speed" and "due regard to weather" — commercial pressure to maintain speed into known severe weather is a SOLAS breach if it results in unseamanlike navigation. ISM Code 5.3 — master's overriding authority. (6) FORMAL RESPONSE TO CHARTERER: write to the charterer (via owner) citing: (a) forecast severity; (b) specific safety grounds; (c) SOLAS V/34 obligation; (d) intention to reduce speed or heave-to. Copy all communications to OLB; (7) DECISION OPTIONS: (a) Reduce speed — arrive late but safely; (b) Divert to shelter; (c) Heave-to and await improvement; (d) Continue at reduced speed monitoring conditions. Proactive vs reactive weather management: one of the most important professional distinctions in seamanship. Waiting until Force 11 actually arrives (option B) means the vessel is already in severe conditions before action is taken. A 24-hour lead time is an ADVANTAGE — use it to assess options while the vessel still has freedom of manoeuvre. Multi-model verification: the MAIB has criticised masters who acted on a single GRIB model output. Professional standard is to cross-reference at least two independent models before making major command decisions based on weather forecasts. Ensemble models (showing the spread of outcomes from multiple model runs) give the best indication of forecast uncertainty. SOLAS V/34 "safe speed": Rule 6 of COLREGs and SOLAS V/34 together require vessels to proceed at a safe speed that allows stopping or altering course in the available distance. Deliberately maintaining high speed into forecast severe weather to meet a commercial deadline — and then suffering damage — is a SOLAS breach. The charterer's laycan (option C): charterparties typically include weather exceptions ("WWD" — weather working days) and force majeure provisions. A master who prudently reduces speed or shelters from severe forecast conditions has a strong case that any laytime / demurrage consequences are covered by the weather exception. The master who maintains speed into severe weather, damages the vessel and cargo, and injures crew — faces: (a) MAIB investigation; (b) MCA inquiry; (c) CoC suspension proceedings; (d) personal criminal liability. The commercial argument for maintaining speed is weak against these risks. Coastguard warning dependency (option D): HMCG and national meteorological services issue gale and storm warnings — but these are general regional warnings. The master uses the specific vessel forecast from the weather routing service and multi-model comparison. The absence of a formal storm warning does not mean the weather is safe.

Question 2

Your chief officer presents a completed passage plan for a transatlantic voyage. As Master, describe your approval process and your legal obligations under SOLAS V/34.

Accepted Answer

PASSAGE PLAN APPROVAL — MASTER'S SOLAS V/34 OBLIGATIONS: SOLAS V/34 LEGAL REQUIREMENT: "Prior to proceeding to sea, the master shall ensure that the intended voyage has been planned using an appropriate chart and appropriate nautical publications for the area concerned, taking into account the guidelines and recommendations developed by the IMO." This is an absolute obligation on THE MASTER — not the chief officer. The master cannot delegate this legal responsibility. WHAT THE MASTER MUST VERIFY IN THE PASSAGE PLAN: (1) APPRAISAL: is the passage planned using the correct, up-to-date charts (latest edition, NTM corrections applied)? Have the relevant nautical publications been consulted (Sailing Directions, Light Lists, Tide Tables, NtM, Notices to Mariners)? Have weather routing service recommendations been considered?; (2) PLANNING: is the passage plan complete from berth to berth? Does it include: (a) waypoints with safe clearing bearings or distances; (b) no-go areas clearly marked; (c) abort points — where is the last point at which the vessel can safely alter to an alternative port?; (d) wheel-over positions for planned alterations?; (e) UKC calculations at minimum water depth points?; (f) speed calculations to ensure arrival at pilot station at the correct tidal window?; (3) EXECUTION CHECKS: are monitoring intervals appropriate to the waters transited? Are danger waypoint checks included?; (4) CONTINGENCY: is there a documented contingency plan for engine failure, medical emergency, severe weather forcing diversion?; (5) MASTER'S SIGN-OFF: the master must sign the passage plan, confirming approval. This signature carries legal weight. SOLAS V/34 — master-specific obligation: the explicit requirement is on "the master" — not "the ship" or "the officer." This is personal legal responsibility. The master who signs a passage plan as approved, having not reviewed it, shares liability with the preparing officer if the plan is found deficient after a casualty. MCA prosecutions and MAIB reports have repeatedly identified inadequate passage planning as a contributing cause of casualties. "Berth to berth" planning: IMO Resolution A.893(21) (Voyage Planning Guidelines) establishes the berth-to-berth principle. The passage plan should begin from the departure berth (including departure draught, UKC at the berth) and end at the arrival berth (including tidal window for berth entry, air draught under bridges). An ocean passage plan that starts "at sea" and ends "at pilot station" is incomplete. No-go areas: on ECDIS, no-go areas should be entered as electronic exclusion zones (safety depth, safety contour) so the system triggers an alarm if the vessel approaches. On paper charts — clearly hatched with red ink. Abort points: for any passage dependent on weather windows or tidal conditions, the passage plan must identify the last point at which the vessel can safely alter course to an alternative destination without committing to the original approach. After the abort point, the vessel is committed. Open-ocean exemption (option C): SOLAS V/34 applies to ALL voyages. The standard of planning may vary — an ocean passage requires less frequent position-monitoring intervals than a coastal passage — but the requirement for an approved plan, considering weather, hazards, and contingencies, applies universally.

Question 3

As Master approaching a port where tides are required for adequate depth, your UKC policy allows 10% of the vessel's draught. At a draught of 14.5m, 10% is 1.45m. The surveyed depth is 16.2m. Tidal height at arrival is 0.8m. Can you proceed?

Accepted Answer

UKC CALCULATION AND POLICY APPLICATION: BASIC UKC CALCULATION: Available water depth = Chart depth + Tidal height = 16.2 + 0.8 = 17.0m. Vessel draught = 14.5m. Static UKC = 17.0 - 14.5 = 2.5m. UKC policy requirement = 10% of draught = 1.45m. STATIC RESULT: 2.5m available vs 1.45m required — APPEARS SUFFICIENT. HOWEVER — THE MASTER MUST CONSIDER DYNAMIC UKC FACTORS: (1) SQUAT: at speed in shallow water, the vessel will "sink" relative to the water surface due to Bernoulli pressure reduction. For a vessel of this draught in 17m of water (h/d ratio = 17/14.5 = 1.17 — VERY SHALLOW), squat could be 0.5-1.0m at standard speeds. Use squat formula or company guidance; (2) HEEL ALLOWANCE: if the vessel is turning or wind-heeled, the draught at the low side increases. A 2° list or heel adds ~0.5m to draught at the side; (3) TIDE PREDICTION UNCERTAINTY: is the 0.8m tidal height taken from a standard tidal prediction? In practice, meteorological conditions can reduce tidal height significantly. A strong onshore wind can ADD height; an offshore wind can REDUCE it; (4) CHART DATUM UNCERTAINTY: is the 16.2m from a recent survey? Chart datum may differ from actual current depths in silting areas; (5) WAVE RESPONSE: in swells, the vessel pitches and the bow drops lower — "hogging/sagging" effects; DECISION: with static UKC of 2.5m against 1.45m required — the margin appears sufficient. But with squat at speed potentially 0.5-1.0m, the DYNAMIC UKC may be as low as 1.0-1.5m. If squat approaches 1.0m, the remaining dynamic UKC is 1.5m — which is at the policy limit. RECOMMENDATION: reduce speed to minimise squat, use VHF confirmation of current tidal height, arrive at the shallowest point at maximum tidal height. UKC policy — static vs dynamic: the most common error in UKC calculations is treating static clearance as the only consideration. Modern UKC policies (and class society guidelines) require consideration of: (a) squat — mandatory for any shallow water passage; (b) heel — for vessels making course alterations or with asymmetric loading; (c) wave response — in swell conditions; (d) tidal uncertainty — applying a tidal confidence margin. Squat in shallow water (h/d ratio close to 1.2): with h/d = 1.17, this is critically shallow for squat purposes. At 10 knots, the Barrass formula gives squat ≈ (Cb × V²) / 100 × Sf (where Sf is a shallow water factor approaching 2.0 for h/d