What is a tidal gate and how should a passage plan account for one?

A. A point on the passage (headland, strait, harbour bar) that can only be safely transited within a specific tidal window — the departure time and speed must be calculated backwards from the tidal gate time to ensure arrival within the window

B. Tidal gates only apply to vessels over 20 metres in length

C. A tidal gate is another term for a tidal stream atlas symbol on the chart

D. A lock gate at a tidal harbour — only relevant to inland waterways

A. The passage plan need only identify the destination — diversion decisions are made in real time

B. A port of refuge provides a safe haven if conditions deteriorate. Suitability factors: accessible in the expected conditions (depth, bar, height of tide); distance from passage track; available facilities (fuel, medical, communications); whether it can be entered at night; holding ground if anchoring is the only option

C. Any port on the chart is automatically suitable as a refuge regardless of conditions

D. Ports of refuge only matter for vessels without an engine — sailing yachts can always divert

A. Night passages are not permitted for vessels without radar — navigation is impossible

B. Only the watch system differs — all navigational aspects are identical at night

C. Night passages require no additional planning — use the same plan as daytime

D. Light identification (lighthouse characteristics, lit buoys); watch system and crew rest schedule; approach to destination in the dark (lights, leading lines, transit); traffic density in the area at night; vessel lighting check; crew experience of night sailing