Doing a 360 degree spin to set compasses

[chengkp75]

Thanks very much! So would it be correct to say that a ship is required to transmit unless ...

 

1. It is under some sort of security threat

 

or a foreign flagged vessel that...

 

2. It is not departing from or destined for an American controlled port

 

3. It is in transit in American controlled waters?

 

I was wondering about this as when Independence was sailing out of Ft. Lauderdale it was almost impossible to ever find the ship anywhere whereas I could find Adventure almost all the time.

 

No. What Aqua posted are the USCG regulations (which basically only apply to US ships) that put the USCG in line with the IMO requirements.

 

IMO requires all ships of all countries above the sizes listed in the USCG file, to transmit AIS signals at all times, unless a specific security risk is present.

 

What the problem is, is that internet, public AIS vessel tracking sites are limited in their capability to receive these signals. When Grandeur left Freeport, Bahamas this week, "Marine Traffic" did not have any position, but a commercial vessel tracking site did have a position, though to get instant updates, you have to buy a subscription, otherwise, it gives a position every 24 hours. The limitations on public AIS sites was purposely made to prevent vessel position information being used for the wrong reasons.

[Ocean Boy]

No. What Aqua posted are the USCG regulations (which basically only apply to US ships) that put the USCG in line with the IMO requirements.

 

IMO requires all ships of all countries above the sizes listed in the USCG file, to transmit AIS signals at all times, unless a specific security risk is present.

 

What the problem is, is that internet, public AIS vessel tracking sites are limited in their capability to receive these signals. When Grandeur left Freeport, Bahamas this week, "Marine Traffic" did not have any position, but a commercial vessel tracking site did have a position, though to get instant updates, you have to buy a subscription, otherwise, it gives a position every 24 hours. The limitations on public AIS sites was purposely made to prevent vessel position information being used for the wrong reasons.

 

Thanks!

[chengkp75]

Back in 2004-2008, when NCL had 3 ships in Hawaii, and the volcano was co-operating by flowing into the ocean, the Captain would stop the ship and swing 360* to give everyone a good view. It seems this may have changed, as some posters on the Hawaii forum say viewing is better on one side. We did this at about 1/3 mile offshore, and we had to shut off the evaporators making fresh water due the volcanic ash in the water, and we had to watch the cooling water to the engines, and tell the Captain if he had to move a little farther away to keep the engines from overheating.

[Krin]

DH and I were on Oasis when the compass was reset. Most people had no idea this was happening. The only way you could tell it was happening was watching the wake. There was no land in sight.

[Capt_BJ]

What the problem is, is that internet, public AIS vessel tracking sites are limited in their capability to receive these signals. When Grandeur left Freeport, Bahamas this week, "Marine Traffic" did not have any position, but a commercial vessel tracking site did have a position, though to get instant updates, you have to buy a subscription, otherwise, it gives a position every 24 hours. The limitations on public AIS sites was purposely made to prevent vessel position information being used for the wrong reasons.

 

 

Well not wrong, but not right either

 

MarineTraffic.com will update positions about every 3 minutes ... just use the window to the site that opens on the POM webcam, left click a ship and a window opens, left click show track .... if you click one of the track points you'll see what the data was at that report .... here's Freedom of the Seas, leaving Port Canaveral right now. Their track from entering this the morning is still in the system

 

Here's Grand' right now ...

 

if you were to zoom out you'd see that the track begins about 15 miles off shore .... b4 that the ship was "out of reporting range"

 

The FAQ at MarineTraffic.com explains a lot about how AIS and this particular site works

http://www.marinetraffic.com/ais/faq.aspx?level1=160

 

short answer - the vessel must be within 20 miles or so of a participating receiving station . . . in some areas there are a lot of stations that play, and in others not so many. Bahamas ... not so many ..

 

Longer answer

As previously posted there ARE commercial pay as you go sites with more data. MarineTraffic.com is a 'voluntary' service and their reporting stations volunteer the information. For example the information collect by USCG operated receivers is not passed to MT.COM. And there's the rub: AIS is low power meant for information exchange from ship to ship - altho the usefulness for land collection is HIGH that was not its original purpose so not in the design. An AIS signal is intended to carry about 15 miles ship to ship. A ship that is not within 15 miles of a land station will not have its position capture by a land service (this will vary depending on the height of the two antenna involved. AIS is VHF-FM which is 'line of sight'). At the MT FAQs you can get a map of their current participating stations. Pay services may well have additional stations obviously. And certain types of vessels actually have 'closed' AIS systems so for example the position of actively patrolling military and law enforcement vessels are not reported except to each other . . .

 

{Technical stuff: The AIS comprises a transmitter (which acts like a transponder

operating in the VHF maritime band) and two receivers. At 2- to 12-second intervals on a moving vessel, the AIS broadcasts the vessel’s identification number, rate of turn, speed over ground, position, course over ground, heading, and a date/time stamp. For vessels at anchor, this same information is transmitted at 3-minute intervals. Every 6 minutes, the system broadcasts the vessel’s International Maritime Organization (IMO) number, radio call sign, name, ship type, ship dimensions, type of position-fixing device used, draft, destination, and estimated time of arrival at the destination. The AIS signal may be received and displayed on board other AIS-equipped ships or ashore at VTS centers.}

 

Today, shore stations are exploiting the 'VTS centers' aspect of the design

Edited July 14, 2013 by Capt_BJ

[Ocean Boy]

I'm glad I asked the question. The info provided has been very interesting.

[TexasRCH]

I have been on 14 cruises and have done this on one time.

[LoyalRoyal 1973]

Back in 2004-2008, when NCL had 3 ships in Hawaii, and the volcano was co-operating by flowing into the ocean, the Captain would stop the ship and swing 360* to give everyone a good view. It seems this may have changed, as some posters on the Hawaii forum say viewing is better on one side. We did this at about 1/3 mile offshore, and we had to shut off the evaporators making fresh water due the volcanic ash in the water, and we had to watch the cooling water to the engines, and tell the Captain if he had to move a little farther away to keep the engines from overheating.

 

How very cool! Insider's comments...love it.

[Suzcruz57]

I had a unique experience on a recent cruise with my sister. We went to the Viking Crown Lounge as we were leaving port in St. Thomas at sunset. We got to see everything as we left and sailed away, right at sunset, as the lights then began to come on back across the island. That experience was amazingly beautiful enough, but then we had an unexpected bonus. The captian came on the PA to tell us all that we were about to pause and do a 360 degree turn in place to set our compasses. We sailed far enough from port to get an amazing view, but were still close to shore with the lights twinkling on land. We stopped in place and the ship turned to the four points of the compass and paused at each of the four points for a couple of minutes. We got a 360 view with pauses and it was awesome. Then, we cranked up and sailed onward. The captain said they just have to do this function rarely. I wish I knew how to know what dates a cruise ship was carrying this function!!!! I would book for that experience again. It seems like a "rare in a lifetime" unexpected event on a large cruise ship. :) Anyone else ever experience such? Stories? I know they try to spin in the Alaska bays when visiting glaciers - I have experienced that, but never a complete circle with pauses like the St. Thomas night. In the glacier bays my memory was they went in, spun 180, and then went out.

We're doing it right now on the Silhouette 2/14/2018. , leaving St Thomas with Capt Peppas. At first we thought there is something wrong, as engines seemed to stop and start, we'd drift a bit, then restart. The Captain came over the PA system to explain what he was doing. Funny guy said " no I'm not crazy." Neat experience 👍🏻

[Pellaz]

What a fascinating thread. THIS is the reason why I love Cruise Critic. (Besides yakking about dress codes in the MDR :) )

 

So now, when we talk to the Captain during the meet'n'greet, we can ask him archly "Soooo....are we gonna do a compass reset during this sailing? Pretty-please, with sugar on top?" :D