Lost at Sea
Longitude
At noon, your watch says 12pm as you would expect.
If your watch was set on Greenwich Mean Time (GMT) it would read 1:00 am at noon in the position your ship is currently in.
Calculate how many hours ahead of GMT you are.
You manage to find a website that describes how you could calculate your longitude.
Use this website to find your longitude and hence your position to notify your rescuers.