Modern cargo ships are huge, slow machines that ply the world’s oceans, delivering fuel, raw materials, and products to power the economy.
Sailing the seas is dangerous. Thanks to safer ships and weather forecasting, it’s not as dangerous as it used to be, but rough seas can sink a modern ship, as we saw when the freighter El Faro sank during an Atlantic storm in October 2015, killing all 33 seafarers aboard.
This September, Irma has been beating its way across the Atlantic Ocean toward the edge of the Caribbean Sea. And cargo ships have been powering away from a broad swath of ocean to avoid the storm. In this case, many ships are seeking shelter on the west side of the islands that mark the eastern boundary of the Caribbean. Their specific routes are chosen by captains with the aid of company headquarters, usually relying on specialized forecasters who work with shippers.
MarineTraffic is a service that tracks the movement of ships using Automatic Identification System (AIS) beacons on board. They sent me images of ship positions from early on September 4th through September 5th. I was able to roughly match those frames with wind-track data provided by the National Hurricane Center, so you can see what it is that the ships are avoiding.