Question 1723Navigation General

The correct answer is B) 2100, 24 January. When a vessel crosses the International Date Line (IDL) heading eastbound, the date changes back by one day. Since the vessel is steaming in east longitude, crossing the IDL at 0900 zone time means it is now 24 January at Greenwich (0 degrees longitude) when the vessel crosses the line. Therefore, the date and time at Greenwich is 2100, 24 January. The other options are incorrect because: A) 0900, 24 January is too early, as the vessel has already crossed the IDL. C) 2100, 25 January is too late, as the vessel has already crossed the IDL and the date is now 24 January at Greenwich. D) 0900, 26 January is incorrect because the date should be 24 January at Greenwich.