FOS maneuver at sea - normal or strange?

[gcvt]

I was tracking FOS as it sailed from St. Thomas to St. Maarten today and something caught my eye. Assuming this image is accurate, can anyone explain why they would make this maneuver? :confused:

 

[boop3]

Hi!

Having been a 'lurker' on Cruise Critic over the years- I have read several post about ships practicing different maneuvers while at sea. Especially when the water is calm and they are in no real rush to get to the next port.

 

Perhaps they took the ship off auto pilot to do manual steering? Or the auto pilot went bonkers? :D. Several years ago when I was on a Princess cruise we did lazy figure 8s one day at sea.

 

Thanks for posting that site. It is very cool!

 

Nora

[Thanna63]

I have no idea but wanted to ask what website or software you were using to track the ship?

If its a website, you can give me a good google search so as to not break any board rules.

 

TIA

[mo&fran]

It is a website sponsered by a University in Greece called marinetraffic.com. No CC isues with that.

[will773]

Seems to me like that would be a glitch in the software or website that you are using. The bottom looks like an angle, not a turn.

[BillOh]

In pure speculation mode, GPS is a wonderful technology, but not perfect. At certain times of the day and in certain locations weird things could happen. They may not have actually done this course. It looks like this is a shallow area? Maybe they were avoiding high peaks, or wanted to keep their engines up to speed, but didn't want to arrive in St Maarten early? I remember Navigator making some strange turns leaving Belize.

[EVALUATOR]

I remember Navigator making some strange turns leaving Belize.

 

When the ships go to Belize, they have to follow the channel approaching and leaving the area where they anchor and tender.

 

You should be able to see the channel on these Google Earth photos.

 

In the photo (use the zoom in/out ) you can see a few cruise ships anchored north of the "M" shaped river channel , and a stream of tenders heading to the port northwest of the ships.

[Eng23]

There was probably road construction going on and they had to go around the barricades that were set up. ;):D Truthfully though it's hard to say what the reason was for this manuever, there could have been some kind of hazard to navigation or like others have said a GPS malfunction or website error.

[Loyal2RCCL]

I ws on the Freedom's Oct. 23rd cruise and the Capt. made an announcement that after leaving St. Thomas they would be making 2 full 360 degree turns to re-calibrate the ships magnetic compass. He said this is done once a year. Perhaps this manuver was for a similar reason :confused:

[will773]

I ws on the Freedom's Oct. 23rd cruise and the Capt. made an announcement that after leaving St. Thomas they would be making 2 full 360 degree turns to re-calibrate the ships magnetic compass. He said this is done once a year. Perhaps this manuver was for a similar reason :confused:

 

That's interesting. I've never heard of that before.

[Pomperaugrr]

The two islands are so close together, RCI often stops the ship and drifts for few hours. I have noticed this at least three times on our recent cruises, where there is no wake and we are just drifting. It usually happens around 9:00 until about 1:00, in my experience. I'm sure if the the conditions are good, it is less expensive than cruising in circles to kill time.

 

Eric

[rwdnj]

It's just the captain teaching his teenage daughter how to steer.:D

[g8rmomx2]

I ws on the Freedom's Oct. 23rd cruise and the Capt. made an announcement that after leaving St. Thomas they would be making 2 full 360 degree turns to re-calibrate the ships magnetic compass. He said this is done once a year. Perhaps this manuver was for a similar reason :confused:

We were on the Freedom a couple of years ago, and the Captain made the same announcement and performed the same manuever after we left Cozumel one evening. It was already dark, and we all went out on deck and watched the lights of Mexico and Cozumel "spin." :)

[TonyFred]

I ws on the Freedom's Oct. 23rd cruise and the Capt. made an announcement that after leaving St. Thomas they would be making 2 full 360 degree turns to re-calibrate the ships magnetic compass. He said this is done once a year. Perhaps this manuver was for a similar reason :confused:

 

I was on the same cruise. We sat in Chops and watched the lights of St Thomas come into view...a couple of times. Kind of neat. The maneuver took a couple of hours. Of course the Freedom is a very big vessel to make two complete circles.

[Sequim88]

they would be making 2 full 360 degree turns to re-calibrate the ships magnetic compass.

 

Hmmmm. I have to do this on my car once in awhile when I go too far west and the magnetic declination adjustment gets off. Here in MN it is almost zero (straight south of magnetic pole) but when we drive to Seattle it gets way off. But I would think that would not be automatic and coordinated with the GPS system.

 

I think I like the drift theory. Especially the straight lines and what look like small corrections before resuming original heading. Wind from NE perhaps?

[snaebyllej]

Hmmmm. I have to do this on my car once in awhile when I go too far west and the magnetic declination adjustment gets off. Here in MN it is almost zero (straight south of magnetic pole) but when we drive to Seattle it gets way off. But I would think that would not be automatic and coordinated with the GPS system.

 

I think I like the drift theory. Especially the straight lines and what look like small corrections before resuming original heading. Wind from NE perhaps?

 

It's not done to adjust to external differences in the magnetic field, but changes in the field of the ship itself. I've been on 2 cruises where they did this, most recently last year on the Westerdam immediately after dry dock (where she had been degaussed).

 

I was going to guess that they were picking up or dropping off a pilot, but it looks too far from shore for that.

[Sequim88]

Whoa. Degausing a ship must be interesting. Bet the IT person loves thinking about all the drives getting wiped. :eek: But seriously, I suppose there would indeed be issues making magnetic compass reliable when onboard a huge pile of steel.

[jcl410]

If you click on each of the ship icons it brings up the data for that AIS report (i.e.; time/speed/course) In this case, the ship appears to be drifting from about 1:20am to 3am mostly at less than one knot.

 

(Note the scale in the picture; the ship only moved about 2 miles in 90 minutes.)

 

At 3am the ship resumed a course of 106 and around 1.5 knots.

 

Aloha,

 

John