You need a 16-hour weather window for a passage. The forecast shows a 20-hour gap between systems. Should you go?

A. Window duration only matters for blue-water passages — coastal passages do not need a weather window

B. Yes — a 4-hour margin is ample and all forecasts are reliable to 48 hours

C. Assess with caution: a 20h window vs 16h passage leaves only 4h margin. Consider: forecast confidence at 48h+ is reduced; if departure is delayed by 2h, the margin halves; if speed is reduced by 20%, the window evaporates. A good rule is: passage time × 1.5 = minimum required window

D. No — never depart unless the window is at least double the passage time

A. Barometric tendency only matters above Force 6 — below that, pressure changes have no predictive value

B. A fall of 6 hPa in 3h is insignificant — barometric changes only matter over 24h

C. A rapid fall (>6 hPa in 3h is defined as "very rapid" in MET Office guidance) indicates an approaching vigorous depression — imminent deterioration. Seek shelter, shorten sail, check position and proximity to lee shores, and reassess the passage plan immediately

D. This indicates a high pressure system building — expect improving conditions

A. Formed when a cold front catches a warm front — the warm sector is lifted off the surface. An occlusion brings a prolonged period of disturbed weather with cloud, rain, and variable winds; the warm sector advantages (relatively settled weather) are lost

B. An occlusion only forms in tropical waters — not relevant to UK sailing

C. Occluded fronts always bring fog and light winds

D. An occluded front is a front that has weakened and no longer has significant weather