Advanced Scenario Check: Gate Failure and Easier Divert

At 0830 in this fictional exercise, the yacht has made 8.0 NM in two hours and now has 16.0 NM remaining to an entrance that must be reached by 1130. The wind is increasing against the stream, one experienced crew member has not slept, and the observed speed made good is 4.0 kn. The easier harbour is 7.5 NM away, is expected to make 5.0 kn on its route and has a fictional latest controlled-entry time of 1030.

Separate the evidence. The gate time and exercise distances are fixed inputs; 4.0 kn is monitored progress; 5.0 kn towards the fallback is an estimate; the wind and crew state increase workload and uncertainty. None of those facts can be repaired by keeping the original planned speed in the passage card.

Test the destination: 16.0 NM at 4.0 kn takes four hours, giving 1230 — one hour after the 1130 gate before any manoeuvring or contingency. The destination plan is closed on the monitored case.

Test the fallback: 7.5 NM at 5.0 kn takes one hour thirty minutes, giving 1000 and only thirty minutes before its fictional 1030 limit. Waiting until 0900 would consume that entire nominal margin before allowing for speed error, entry or manoeuvring. The easier decision exists now, not indefinitely.

Brief the divert, immediate course and sail plan, navigation and lookout roles, support for the unrested crew member, the next position and weather review, plus the condition for further change. Record why the destination closed and the calculations used. This lesson rehearses written judgement; it is not a live route, harbour or weather recommendation.