Your vessel drafts 9.8m and is entering a channel with a charted depth of 11.5m. Speed over ground is 12 knots. Your examiner asks you to explain squat and calculate whether your underkeel clearance is adequate.

A. UKC = charted depth minus draft = 11.5 - 9.8 = 1.7m. No further calculation is required — squat is already accounted for in ECDIS safety contour settings.

B. Squat is the rolling motion of a vessel caused by beam waves. It does not affect underkeel clearance. The available UKC is 11.5 - 9.8 = 1.7m which is adequate at any speed.

C. Squat only occurs in channels narrower than 3 ship-beam widths. In this open channel at 11.5m depth there is no squat effect.

D. Squat is the bodily sinkage and change of trim a vessel experiences when underway in shallow water due to the Bernoulli effect. Using Barras formula for open water: squat = Cb x V squared / 100 (in metres), where Cb is block coefficient and V is speed in knots. At 12 knots with Cb approx 0.75: squat = 0.75 x 144 / 100 = 1.08m. Available depth = 11.5m. Draft + squat = 9.8 + 1.08 = 10.88m. UKC = 11.5 - 10.88 = 0.62m. This is marginal — most companies require 10-15% of draft UKC minimum (0.98-1.47m). Speed should be reduced.

A. SOLAS V Reg 34 requires a passage plan only for voyages exceeding 200 nautical miles. For shorter voyages a verbal brief to the OOW is sufficient.

B. 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).

C. SOLAS V Reg 34 requires the Chief Officer to produce the passage plan and present it to the master for signature. The OOW has no planning responsibility.

D. The four stages are: depart, transit, arrive, anchor. SOLAS V Reg 34 specifies that plans must be filed with the port authority before departure.

A. A 6.5m shoal with 7.2m draft has 0.7m of clearance. This is within MCA-approved underkeel clearance limits and no special marking is required.

B. Check the tide tables — if the tide adds 1m of water at the time of passing, the available depth is 7.5m which exceeds your draft of 7.2m with 0.3m to spare. Mark this as a tidal gate in the plan and proceed.

C. 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.

D. Report the discrepancy to the chart agent as a possible chart error and proceed on the original route pending correction.