A reader of cruise expert Professor Ross Klein’s website raised an interesting question why a AIS chart of the Thomson Dream cruise ship (via marinetraffic.com) showed the ship sailing in a weird pattern.

The experts I have discussed this with don’t think that the pattern resembles one to be taken if the ship were conducting a man-overboard search. Another thought was that the cruise ship may have been responding to another vessel in distress perhaps, although this seems unlikely too. An practice exercise is also a possibility, although nothing in particular comes to mind. 

No ship would take this course as a part of its normal itinerary considering the fuel that would be wasted.

Assuming the AIS positioning is accurate, what was going on?  I don’t know. Can anyone on the Thomson Dream explain the ship’s maneuvering? 

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Thomson Dream AIS

  • xyz

    Not sure what ports it was sailing from/to. The ships now sail at considerably slow speeds to save fuel. There are more seadays now so that people spend time on board and buy drinks,spend money onboard. So while the distance between two ports is the same the ship now has more time to reach the two ports. So the ships speed is reduced according to ETA. This slow speed irritates some passengers and they rush to complain to senior management on board/reception. That is why speed is increased and ship move in circles. I know a UK liners stop at sea because it had 38 hours to reach St. Peters port from Southampton. Distance between Southampton and St. Peters Port is 97 nautical miles. 97/38 = 2.57 Knots/Hour. So at 2.57Knots/hour it will reach st.peters port from Southampton. While normal cruise speed is around 20Knots/hour

  • Ian Moores

    Jim, looks to me like she arrived at the port entrance too early, or the port or pilot were not ready for her. She has arrived at her “decision point” to continue and at that stage has taken a couple of round turns until the port were ready for them. Pretty standard practice and the safe option rather than approach too close to the port and then attempt to back and fill at a late stage when there is less sea room.