Navigation and Passage Planning
The Navigation and Passage Planning domain examines whether you can take a ship from berth to berth on a route that is planned, monitored and auditable, and defend each decision in that plan under examination pressure. Administrations expect the IMO framework in Resolution A.893(21) to be visible in your answers and in the ship's actual plan.
The four stages
- Appraisal: gather everything relevant - charts and ENCs with their CATZOC, sailing directions, notices to mariners, tide and current data, weather, traffic, port requirements, the ship's manoeuvring data and the company's ISM procedures.
- Planning: produce the plan itself - tracks with cross-track limits, no-go areas, wheel-over points and radii, abort points, contingency anchorages, the UKC policy, look-out and reporting requirements, and every position where the plan changes.
- Execution: conduct the passage with the plan in force; a plan is a working document, not a suggestion.
- Monitoring: fix position by more than one method and compare the ship with the plan continuously, not at the end of the watch.
Under-keel clearance
UKC = charted depth + height of tide − draught − squat − allowances for swell, heel, density and chart accuracy. Company policy commonly sets the minimum near 10 per cent of draught with an absolute floor. Squat grows in shallow water and with speed, and differs between even keel and trimmed conditions, so use the ship's own squat table rather than a rule of thumb.
ECDIS discipline
Set the safety contour and safety depth deliberately, run the route check, confirm alarms are not silenced, and keep an independent check by visual bearings, radar or parallel index. Know and be able to state your backup arrangement.
Worked example
Draught 12.5 m; charted depth 15.0 m in a CATZOC A1 area; height of tide 2.3 m; predicted squat 0.6 m; no swell allowance. Net UKC = 15.0 + 2.3 − 12.5 − 0.6 = 4.2 m. Required UKC at 10 per cent of draught is 1.25 m, so the transit is acceptable with 2.95 m in hand - provided the tide is confirmed by observation and the vessel holds the planned speed and track.
Traps that cost marks
Treating chart datum as real depth; applying a tidal height without checking the time of high water and the stand of the tide; ignoring squat or using a single rule of thumb; describing the ECDIS safety contour as if it were a physical barrier; giving no abort point or contingency; and quoting a plan with no monitoring method attached.