You are tasked to take a 120 GT survey vessel up a tidal river on a rising tide. The air draft of the vessel is 6.5m. There is a fixed bridge in the passage with a charted clearance of 5.8m at MHWS. What do you need to do before transiting under the bridge?

A. Bridge clearance calculation: charted bridge clearance is referenced to MHWS (Mean High Water Springs) — the highest regular astronomical tidal level, NOT LAT. This means at MHWS, the clearance is 5.8m. On a rising tide, the water level may be approaching MHWS — which means the clearance is REDUCING as the tide rises, and at MHWS the clearance is at the charted minimum 5.8m. Your air draft is 6.5m — the vessel will NOT fit under the bridge at MHWS (5.8m clearance vs 6.5m air draft). To transit safely: you must pass under the bridge at a sufficient time BEFORE high water, when the tidal height is LOW enough that the actual clearance exceeds your air draft plus a safety margin. Calculate: required clearance = 6.5m + margin (e.g., 0.5m safety) = 7.0m. Required water level reduction = 7.0 − 5.8 = 1.2m below MHWS. Find the time when tidal height is 1.2m below the day's MHWS height — this defines your transit window.

B. Charted clearances are always at LAT. Add the tidal height to the charted clearance to get the actual clearance at the time of transit.

C. On a rising tide the water level is increasing, so the clearance is also increasing. Transit under the bridge on the rising tide for maximum clearance.

D. Bridge clearances are fixed physical measurements. Tidal height does not affect the bridge clearance — only the water depth below the vessel changes with the tide.

A. STCW Regulation II/3 OOW Near-Coastal certificate permits: watchkeeping officer duties on ships of less than 500 GT engaged on near-coastal voyages only. Near-coastal: defined by the flag state — in the UK (MCA), near-coastal means voyages within the sea area defined in Merchant Shipping Notice MSN 1861 (MCA-defined near-coastal waters including UK coastal waters, and areas agreed with specific flag states). Limitations: (1) The certificate is NOT valid for unlimited oceans voyages; (2) NOT valid on ships 500 GT or above; (3) The holder cannot act as OOW on international voyages beyond the near-coastal limit without holding STCW II/1 (OOW Unlimited); (4) Near-coastal OOW in STCW covers the STCW II/3 competencies which are the same functional areas as II/1 but assessed at the operational level appropriate to near-coastal operations and vessels under 500 GT.

B. An OOW < 500 GT Near-Coastal certificate permits watchkeeping on any vessel under 500 GT in any sea area worldwide, including oceanic passages.

C. The near-coastal certificate is valid for all vessels where the Master holds an unlimited Master certificate. The OOW certificate limitations are overridden by the Master's qualifications.

D. STCW II/3 applies only in territorial waters (12nm). Beyond 12nm, an OOW NC certificate is not valid and a full STCW II/1 certificate is required.

A. Tidal stream planning: (1) Extract tidal stream data from the relevant tidal stream atlas or chart tables — timing referenced to HW at the nearest standard port; (2) Calculate the tidal stream vectors for each hour of the passage (direction and rate vary through the tidal cycle); (3) Vector triangle method: plot course to steer (CTS) to achieve the desired track made good — add own ship speed vector and tidal vector to calculate the heading required to maintain the track; (4) At 3.5 knots tidal stream vs 9 knots own speed, the cross-tide component at 90° would require approximately 23° of course correction; (5) Calculate ETAs using speed made good along track (not ship speed); (6) Identify timing of fair vs foul tide — plan departure to favour the fair tide for the main channel crossing; (7) Check for minimum depth at tidal gates — arrive at the gate when sufficient water depth exists.

B. Apply the tidal stream as a compass correction. Add 3.5 knots to own speed when the tide is following, subtract when the tide is foul.

C. Tidal streams only matter in the last mile of a channel approach. Plan the open sea passage on the gyro course and apply tidal correction manually on final approach.

D. At 9 knots, tidal streams below 4 knots have negligible effect on track. No tidal correction is required until tidal stream exceeds own ship speed.