Question 1

Your vessel arrives at Immingham with a draught of 12.6m. The port authority states the minimum available depth is 13.8m at High Water Springs (MHWS). The tidal range is 4.8m. Calculate when you can enter.

Accepted Answer

TIDAL WINDOW CALCULATION — IMMINGHAM: VESSEL DRAUGHT AND UKC REQUIREMENT: Draught = 12.6m. Company UKC policy: 10% of draught = 1.26m. Minimum required depth = 12.6 + 1.26 = 13.86m, rounded to 13.9m. AVAILABLE DEPTH: the port states 13.8m at MHWS (Mean High Water Springs). The MHWS is the average of the highest spring tides. TIDAL RANGE AND LEVELS: if MHWS = 13.8m (from chart datum) and MLWS = 13.8 - 4.8 = 9.0m (Mean Low Water Springs). In tidal calculations, we need the depth at a specific time, not just MHWS. MORE ACCURATELY: The tidal height prediction for the specific day of arrival determines available depth: Available depth = Chart datum depth + Tidal height at time T. Required depth = 12.6 + 1.26 = 13.86m. Chart datum depth (from Admiralty Tide Tables / EasyTide): let us say chart datum depth at the approach channel = 9.2m. Then required tidal height = 13.86 - 9.2 = 4.66m. Check the tidal predictions for the day — at what time does the tidal height reach 4.66m on the rising tide? Subtract the transit time through the approach channel. RESULT: only certain times near high water will give sufficient depth. Calculate based on the specific day's tide predictions from Admiralty Tide Tables or the UK Hydrographic Office EasyTide website. VESSEL TRIM: also consider trim — the deepest draught point. If the vessel is 0.3m by the stern, the stern draught is 12.75m, requiring additional tidal height. UKC policy application: the company's UKC policy specifies the minimum clearance below the keel. Simply having 1.2m physical clearance (13.8 - 12.6 = 1.2m) is not sufficient if the UKC policy requires 1.26m (10% of 12.6m). The policy requirement takes precedence over the physical minimum. Tidal height varies: MHWS is a MEAN (average) — the actual spring high water on a given day may be higher or lower than the MHWS. In apogean springs (when the moon is at apogee), the spring range is lower. In perigean springs (moon at perigee), the spring range is higher. Use the actual day's predictions from Admiralty Tide Tables, not just MHWS. Transit time: the tidal window is not just about the arrival depth — the vessel must have adequate depth throughout the approach channel transit. If the approach takes 2 hours, the vessel must have adequate depth for the entire 2 hours. Calculate the tidal window as: (time of adequate depth commencement) + (transit time margin). Trim effect: for a vessel with stern trim, the deepest point is the stern. UKC calculations must use the MAXIMUM draught — not the mean draught. If the vessel is trimmed 0.3m by stern with a mean draught of 12.6m, the stern draught may be 12.75-12.80m. This increases the tidal height requirement. The port authority role: while port authorities provide guidance on tidal windows, the final navigation safety decision (including whether the UKC policy is met) remains the master's responsibility. The port authority's advice is guidance — the master must independently verify using the vessel's draught and UKC policy.

Question 2

As Chief Mate, you are responsible for preparing the passage plan for a voyage from Rotterdam to New York. Describe the APEM framework you use and what the master must approve.

Accepted Answer

PASSAGE PLANNING APEM FRAMEWORK: IMO Resolution A.893(21) — Voyage Planning Guidelines. The APEM framework has four stages: (A) APPRAISAL: gather all relevant information before planning: (1) Nautical charts — identify correct editions, apply NtM corrections. Use largest scale available for all coastal sections; (2) Nautical publications — Sailing Directions (NP27 Bay of Biscay, NP69 North Atlantic, US East Coast Pilot), Light Lists, Tide Tables, Tidal Stream Atlas; (3) Weather routing service — seasonal North Atlantic winter storm track, pilot charts showing prevailing winds, currents, ice limits; (4) Notices to Mariners — weekly, check latest edition NTMs for all charts to be used; (5) Ship's draught and UKC requirements at departure and arrival; (6) Vessel characteristics — manoeuvring data card, stopping distances; (P) PLANNING: using the appraisal information, plan the complete voyage: (1) Berth-to-berth — departure berth Rotterdam, arrival berth New York including pilot boarding ground; (2) Waypoints with clearing bearings/distances from dangers; (3) No-go areas — shoals, traffic separation zones, exclusion areas, offshore installations; (4) Abort points — last point to turn back to Rotterdam safely; (5) UKC calculations at critical shallow sections; (6) Speed calculations for pilot station arrival time and tidal window; (E) EXECUTION: monitoring the voyage against the plan; (M) MONITORING: comparing actual position against planned track throughout. MASTER APPROVAL: the Master must sign the plan before departure — SOLAS V/34 legal obligation. APEM standard — universal application: APEM applies to ALL voyages including ocean passages. The depth of each stage varies with voyage complexity, but an ocean Atlantic crossing requires: (a) seasonal weather routing consideration (North Atlantic in winter — Genco/Maersk weather routing service); (b) ice limit consideration (Grand Banks area — seasonal icebergs from March to August); (c) North Atlantic shipping lanes (SOLAS Regulation for routeing); (d) GMDSS provision for the sea areas (A1/A2/A3 coverage). Chief mate's role in passage planning: in practice, the chief mate prepares the voyage plan and presents it to the master for approval. This is standard industry practice reflected in STCW competence requirements for STCW II/2 (Chief Mate). The STCW Chief Mate Certificate of Competency examination includes passage planning as a key competency. Master sign-off requirement: the master is ultimately legally responsible under SOLAS V/34 for ensuring the voyage is properly planned. In practice, the master reviews and approves the plan — but the chief mate prepares it. The master's approval signature has legal significance in any investigation. Great circle only (option C): while great circle routing is the default for ocean passages, the passage plan must still consider: (a) ice limits in the Great Circle track area; (b) Traffic Separation Schemes; (c) pilot boarding grounds; (d) UKC at port approaches. A bare great circle with no additional planning is not a complete passage plan for a SOLAS V/34 purpose.

Question 3

As Chief Mate, it is your responsibility to maintain the vessel's ECDIS and charts. Describe your procedure for ensuring all charts are up to date for a voyage.

Accepted Answer

ECDIS AND CHART MANAGEMENT — CHIEF MATE'S PROCEDURE: ECDIS CHART MANAGEMENT: (1) ENC SOURCE: Electronic Navigational Charts (ENCs) are sourced through an authorised distributor — AVCS (Admiralty Vector Chart Service), PRIMAR, or equivalent national chart authority. The subscription must be current; (2) WEEKLY UPDATES: AVCS provides weekly ENC updates. The chief mate must: (a) connect the ECDIS to the update service weekly; (b) download and apply all updates to ENCs covering the upcoming voyage; (c) verify update application — some ECDIS systems show "cells updated" count; (3) NtM CHECK: for paper charts (on ECDIS backup charts or paper chart primary systems) — weekly Notices to Mariners (NtM) must be applied. UK Hydrographic Office NtMs are published weekly. Each NtM specifies the chart number and correction. Mark each chart in the NtM index with the correction number applied; (4) CORRECTION LOG: maintain a Chart Correction Log recording: chart number, edition, NtMs applied, date of correction. This is a statutory record; (5) CHART CATALOGUE: the Admiralty Chart Catalogue specifies which charts are required for the planned voyage. Ensure all charts are: (a) latest edition; (b) all NtMs up to the current week applied; (6) NEW EDITIONS: when a chart is re-issued (new edition), all previous corrections on the old edition become incorporated. Order the new edition and apply subsequent NtMs from the new edition date; (7) T&P NOTICES: Temporary and Preliminary Notices to Mariners (T&Ps) apply to ENCs as Cell Update information — check these separately from permanent corrections. Frequency of NtM updates: the UK Hydrographic Office (and other hydrographic offices) publish corrections weekly. The MAIB has investigated groundings where the cause was an uncorrected chart — the most common pattern is a temporary or preliminary notice that changed a depth, moved a buoy, or added a new hazard. Investigations routinely check when the last NtM update was applied. SOLAS standard: SOLAS V/27 requires ships to carry adequate and up-to-date charts. "Up to date" means NtMs applied to the current week. Outdated charts are a PSC deficiency. The MCA's Concentrated Inspection Campaign on navigational equipment in recent years specifically targeted NtM compliance. Automatic ECDIS updates (option C): ECDIS does NOT automatically update charts without action. The chief mate must: (a) have an active subscription to AVCS or equivalent; (b) download updates from the update server; (c) apply them to the ECDIS. The process is not automatic — many ECDIS groundings have involved failure to update ENCs. Chart Correction Log requirement: the requirement for a Chart Correction Log is implied by SOLAS V/27 ("adequate and up-to-date charts") and MCA MGN guidance. The Log is not explicitly required by a single SOLAS regulation but is standard practice and expected by PSC. In any grounding investigation — the chart correction log will be examined to verify the chart was current at the time of the incident.