Navigation: A.I.S
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Category: Maritime Knowledgebase
Forum Name: Navigation
Forum Discription: All discussions related to Navigation Equipments, aids and developments can be discussed here.
Printed Date: 21 Jul 2024 at 4:11am
Software Version: Web Wiz Forums 8.02 -

Topic: A.I.S
Posted By: Biplab Ray
Subject: A.I.S
Date Posted: 06 Mar 2003 at 3:22pm

Posted By: Sriram Rajagopal
Date Posted: 12 May 2003 at 7:02am
the AIS consists of a display unit (like the GPS) connected to 2 receiver and 1 transmitter antennae. It transceives on VHF (ch.88B and 87 B - info transmiteed includes vsl csign, IMO no, MMSI, co, spd, type, navigational status, ROT, GPS posn, and more info as per IMO res. 893 (21) - you can do a google search for this imo res and download all of it. The display shows vessels as targets like on a radar PPI (though this is much smaller, about 4 inches x 6 inches). each target has nothing more than the MMSI displayed. On clicking on a particular target, its further details are displayed. There is a popular misconception that the AIS has to be shown on an electronic chart. The AIS MAY be connected to ecdis and radar, but the primary display remains the AIS display unit. It receives inputs from GPS, gyro, log, etc. It is to be always switched on, tested min once a month / voyage, works on TDMA - time division multiple access (like CDMA for mobile phones). If you do a google image search for automatic identification systems, or go to the uscg ais page, you can see what it looks like. The dates of fitting have been advanced due to security concerns - new ships already have it, psngr and tankers must be fitted with it by july 2003 (this year) and all other vessels >300 GT by july 2004, or the next saf-equip survey, but definitely by dec 2004. US federal regs require it to be fitted on all vsls more than 20 m long. The IMTC - International maritime training center in powai ( has a security course which we shippies will have to do (SSO shipboard security officer) by the isps implementation dates (july 2004) - it has a lot of info on AIS.

Posted By: Sameer Singh
Date Posted: 14 Sep 2003 at 5:43pm
A lot of misinformation here, I believe, as the data is probably too theoritical. i have worked on a vessel with AIS, and it is not like how it has been described. The details about the display etc are Maker specific. Different makers have different models. The one I worked with, a Furuno model had only 1 gps internal receiver, not any external one. There were a couple of different displays that the user could select, either like a radar PPI, or a list sorted out as per range of each vessel. The main prblem lies in the navigating officers not checking that own ship data is correctly fed. I had Jahare Viking pass a few miles off, and it was showing that it is "Sailing"...not that I saw any sails on it. Then again some of the officers forget to correctly input the Nav status, and are showing Constrained by Draught in + 2500m of water. It will be some time before the officers become familiar with this new equipment. The latest supplement o the Mariner's Handbook regarding this is quite an interesting read, and all navigating officers worth their salt must go through it at the first oppurtunity.

Posted By: Mohit Kapoor
Date Posted: 15 Sep 2003 at 2:42pm
Guys AIS is a common sense system. There is basically an antenna which radiates info of own vessel & at the same time receives info from AIS antenna of other ships. This info includes GPS data which is inbuilt plus a lot more add ons. AIS display on bridge shows the details which are received by the antenna. If the radar is interfaced with AIS then all the info can be seen on the screen. So no more "Ship On My Dead Ahead ..........." Ha ha ha!

Posted By: Anonymous
Date Posted: 20 Oct 2003 at 3:51pm
Since you had put up your query for AIS . I had an AIS fitted on my last ship and was closely associated with the installation and operation of the AIS. We had a JRC AIS fitted on board. The AIS as the name suggests is for auotmatic identifiaction of the ships present in range. Once it is operation it automatically provides information on the other ship. The information include the name, MMSI number, IMO number, navigational staus, type of ship, number of crew, and the position. Same way it transmits own ship data to other vessels in vicinity. For this it is imperative that you keep on updating own ship data as per voyage. This includes whether you are navigating or at anchor or at berth, whether the ship is loaded or in ballast and the ships draft. The AIS has provision of communicating with any of the vessels in its range and message can be sent form its menu.It has provision of entering the waypoints for the voyage is also optional. There is gyro feed to the AIS and it also gives the range and bearing of the vessels in range. That can be compared with radar to get an overall picture. AIS operation is certified by the class and there is a certification issued for correct operation of the sysytem in par with the SRT. If you have any more queries you can contact me at Yours sincerly Anindam Mandal

Posted By: Hamid
Date Posted: 27 Oct 2003 at 8:33pm
As have been mentioned above by many contributors, the major problem in the AIS system which needs to be addressed is the fact that the Voyage Data is not updated by the officers onboard at the commencement of every voyage. During my recent contract on a VLCC, a majority of the times I have found that either the Navigation Status or the ETA and Next Port details of the passing vessels have not been updated. In many cases it was so out of date that probably it was never updated after its installation. One way to avoid this kind of situation , which we are following, is to incorporate this task (of updating the AIS) in the checklist for the Pre-Departure controls tests.

Posted By: sapnish
Date Posted: 01 Jan 2004 at 1:02pm
I guess we are living in the information age, that does not necessarily mean that we have to bottleneck ourselves with unnecessary infos. basic idea of A.I.S is collision avoidance,as long as vsl id is fed in that's all is reqd to identify the target vessel that is of,just take it easy.

Posted By: Anonymous
Date Posted: 28 Mar 2004 at 2:15am
AIS may not give a correct picture of the traffic due to AIS malfunction, AIS switched off, No requirement etc. Therefore AIS is not an equipment that is included as part of the collision regulatiuons in other than "by all means". Please don't use AIS blindly for collision avoidance. AIS is to improve the quality of info to the OOW to improve the situation awareness. The vessel and dynamic info from an AIS is automatic therefore will always be correct. Only the voyage info needs to be updated. SO if some vessel has not updated its voyage info - don't worry - its not important. In times to come I see it as a replacement for our good old RADAR. But for the time being it has some drawbacks.

Posted By: shoaib muneer
Date Posted: 12 May 2004 at 4:46am
Good idea to point out problum to each other. I am marine communication/Navigation engineer since last 30 years, still I am facing problum with new technoligy as 30 th year before. Pls call me if you have any problum. shoaib muneer (Karachi-Pakistan.)

Posted By: Jabberwocky
Date Posted: 01 Dec 2005 at 12:25pm
AIS is a good support to the radar, as long as it works. Sadly, it's implementation has been hurried (Without rigorous operational tests by manufacturers) and one finds innumerable vessels at sea who 'claim' to be sailing, moored, still bound for their previous port, going on a reciprocal course, or simply having the name "Nauticast". Unfortunately, most ship owners / managers will never upgrade to a better model and there are gonna be lots of ppl stuck up with AIS sets which confuse others rather than being of use}!

Posted By: Arya Pattanaik
Date Posted: 28 Mar 2006 at 4:21pm
Please be informed that recently there was a case where it was found that the OOW of the ship was busy with the AIS sending message to the other ship where he should have been taking action instead and which resulted in a collision between both the ship.As there are so many companies where typing message is a time taking and complicated thing.So be careful when using AIS it can be only a AID, Also as stated above due to so many job and paper work on shipu forget to update the navigational information. Please remember this is a part of ISPS and to be used with caution while navigating, as now a days the traffic density is increasing at enourmous rate so we have to be very careful all the time while navigating.AIS certainly a good thing but always to be used with caution.

Posted By: sydney bellet
Date Posted: 08 Jul 2011 at 10:27pm
Guys its just an Aid to Navigation, 2 modes static n dynamic, ships info relayed to ships in and around its range, its the duty of the oow to double check the status on the AIS as its a must, after 9/11 americans wanted to know whats happening in and arnd their waters so what did they do AIS... genius only things is they already had a way of tracking whats in their waters for over a 100miles so the questions is why did the AIS come in to force ?????

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