Question 1

You are navigating a coastal passage using ECDIS. Your examiner asks: "What are the key limitations of ECDIS that an OOW must be aware of?" Name at least 5.

Accepted Answer

Key ECDIS limitations: (1) ENC data quality varies — some cells are based on old surveys with poor depth accuracy; (2) chart datum may differ from GPS datum causing position offsets; (3) anti-grounding alarms require correct safety depth/contour settings — poorly configured alarms give false security; (4) display scale can create generalisation errors; (5) software/data update failures may mean the ENC is not current; (6) ECDIS failures (power, software) require immediate switch to backup; (7) over-reliance can reduce situational awareness and lookout effectiveness. ECDIS limitations are a core OOW oral topic, particularly since multiple MAIB and AAIB investigations (MV Ovit, MV Westerdam) identified ECDIS over-reliance as a causal factor. The MSC-FAL.1/Circ.3 (2017) "Guidance on the safe and integrated use of bridge systems" specifically addresses over-reliance. Critical points: (i) IHO data quality indicators (ZOC A1 to U) must be understood — ZOC U/D areas have unknown/unreliable depths; (ii) safety depth and safety contour settings must be correctly configured for each vessel and voyage — a safety contour set to 5m on a 7m draft vessel gives no protection; (iii) GPS/chart datum mismatch — the GPS gives WGS84 positions but older charts may use local datums with offsets of hundreds of metres. An OOW must actively cross-check ECDIS against radar, visual fixes, and depth sounder.

Question 2

Your examiner asks: "What does SOLAS Chapter V Regulation 34 require regarding passage planning, and what are the four stages of passage planning?" Give a complete OOW answer.

Accepted Answer

SOLAS V Reg 34 requires that before proceeding to sea, the master shall ensure that the intended voyage has been planned using adequate and up-to-date charts and nautical publications. The four stages are: APPRAISAL (gather all relevant information); PLANNING (lay the plan on charts from berth to berth); EXECUTION (monitor progress against the plan); MONITORING (cross-check position continuously throughout the voyage). SOLAS V Reg 34 (Voyage planning) requires passage planning for ALL voyages — there is no distance threshold. IMO Res. A.893(21) "Guidelines for Voyage Planning" expands on the four stages. APPRAISAL: collect charts, publications, NOTAMs, weather, port information, draft restrictions, tidal windows. PLANNING: no-go areas, waypoints, abort points, contingency anchorages, speed profiles. EXECUTION: confirm plan implemented at departure and each watch handover. MONITORING: continuous position fixing, comparison with plan, CPA checks on all traffic. "Berth to berth" is the key phrase — the plan must cover the vessel from the departure berth to the arrival berth, including port approaches.

Question 3

During passage appraisal, you identify a shoal with 6.5m charted depth on your route. Your vessel drafts 7.2m. Describe how you would handle this in the passage plan.

Accepted Answer

The shoal is a no-go area. You would draw a no-go zone on the chart with a safety margin added for squat, wave response, tidal variation, and chart accuracy. A clearing bearing or limiting danger line would be drawn to keep the vessel safely clear. The passage plan waypoints must route the vessel outside this zone. The abort point where you could no longer safely turn back or divert must also be marked. A charted depth of 6.5m with a draft of 7.2m means zero underkeel clearance — the area is a no-go zone regardless of tidal height. Tidal heights add water but introduce uncertainty (sounding datum, tidal prediction errors, storm surge/set-down). The safety margin for no-go areas must account for: squat (speed-induced sinkage); heel; tidal prediction error; chart datum uncertainty; wave response; and sea state. A clearing bearing is a compass bearing drawn on the chart: as long as the bearing to a landmark or buoy is greater/less than the charted value, the vessel is safe. Limiting danger lines run parallel to the track at the minimum safe passing distance from the hazard. Both are standard passage planning tools examined at OOW level.