Advantages of Automatic Chart Corrections


Correcting charts manually is a monotonous affair and prone to errors. Automatic updates remove a major source of human error.

Labour and time saving

The number of charts required to be corrected depends on the size of portfolio carried by a ship. ISM requires all charts on board be kept updated. A ship could carry up to 5000 paper charts. Automatic updating of charts saves thousands of man hours otherwise spent on manual chart corrections. This job carried out by the navigating officer is repetitive, tedious and downright boring especially when there are hundreds of charts to be corrected every week.


Master gets the corrections when he wants like before entering a busy harbour or transiting through a tricky narrow channel. He doesn’t have to wait for the NtM packs to reach by post. 

Cost effectiveness

Chart service providers normally incorporate cost of corrections at the time of buying the ENCs. This is a yearly cost recovered at the time of renewal of licenses. The logistical cost ofupdates is minimum as they are disseminated through the net. As far as the end-user is concerned there is no separate charge for the updates. One year updates are paid for at the time of annual subscription. An important advantage of automatic updates is if you do not receive the previous update DVDs the chain of corrections is not broken. Whereas if you miss an in-between NtM booklet you will have to order it again. In the ship’s bridge you will find many drawers are filled with old NtM packs. Since it is very difficult to correct all charts on receipt of the NtMs, the mariners save old NtM packs to be used later like when there is a change of route and different charts are required. At that time the uncorrected charts are taken out from the drawers and corrected from the old NtM packs stored in the drawers.

Ships generally do not have a policy for preserving the old NtM packs. When she runs out of storage space old packs are disposed off. Sometimes Masters do not trust corrections of old charts carried out diligently and order for new ones even if they are not superseded.

Reduced carbon footprint

Transport those heavy NtM packs around the world adds to the carbon footprint.

Marine Incidents

An uncorrected chart is a threat to the safety of a vessel. If you knew that there would be an incident every time you sailed with bad charts then you would be more careful. It is because people get away with uncorrected charts very often that you are tempted to take chart updating lightly.

When you consider the cost of a vessel and its cargo, the accuracy of the chart becomes paramount. Even a single incident can cost millions.

How often does an incident occur? This is a difficult question to answer. If we go by the pyramid philosophy then for every reported incident there are 100 more which were never reported. For those who are interested to know about marine accidents look in the IMO's GISIS database. Or take a look at MAIB, BSU, ATSB, NTSB, TSB Canada, Marshall Islands and Isle of Man reports online. You might see if the Nautical Institute's MARS database has something and the Confidential Hazard Incident Reporting Programme.

There are quite a few incidents caused due to charts. Examples for not updated charts are Joshua Slocum and Globtik Sun, inaccurate/old charts (Pacific Challenger, Sanko Harvest, Rocknes, Octopus, Sea Diamond), use of inappropriate chart scale, wrong charts entirely. Sometimes it happens.

There is an interesting site ‘Centre for Tankship Excellence’ created by a naval architect, Jack Devanney. He is a career tankerman and has spent a lifetime in the tanker industry. He started this portal because he felt the oil tanker industry has lost its way. It is a very well researched web site for those in the tanker industry. Here there is a database of tanker casualties that is openly available to the public. If we check this compendium of large tanker casualties and spills we can get a fair idea of marine incidents caused due to navigation errors listed under NC. Shortening this list further to only those primarily caused due to bad charts meaning either ship did not update the charts or did not carry the appropriate charts, here is the list:

Date - Ship - Name - Dead - Volume - Comments

1975-08-15 globtik sun 61110000 hit platform off Galveston, bad charts, bad plotting

1984-10-01 aguila azteca grounded off Bermuda, chart inadequate, reef not shown, no spill

1991-02-14 sanko harvest N 750000 chart not uptodate, hit poorly surveyed shoal, sank

At 0130 on August 15, 1975, M/V Globtik Sun struck an unmanned Chevron Oil Company oil production platform approximately 100 miles from Galveston while en route from Aruba to Baytown, Texas. …..Apparently, the ship was on autopilot with the radar turned off when the watch was relieved at midnight. The charts that were in use were not up-to-date and showed no fixed structures on the ship's trackline. When the radar was turned at 0030, nothing was visible. At 0045, the radar revealed an object approximately 9 miles away on the starboard side of the vessel. The Captain of the vessel claimed that he saw no navigational lights on the platform even though a Chevron spokesman said they were functioning properly. The mate failed to plot the object. At 0130, the port bow of the vessel struck the eastern side of the platform, opening up a gash 2 feet wide by the length of the bow tank….. The Globtik Sun was later sold for scrap.

Sanko Harvest was approaching Esperance at the end of a voyage from Florida loaded with fertilizer. She had to pass thru the incompletely surveyed Recherche Archipelago. She struck on a shoal that was uncharted, but the Australians had issued a correction which noted this shallow area without giving the depth. This correction had not been entered on the Sanko Harvest's charts.

There are some other websites such as Marine Accident Incident Board (MAIB) which maintain similar databases.

In the MAIB there is no separate list of accidents caused due to charts. Here I found an interesting incident. The ship Pride of Canterbury ran over a wreck which the navigators on board probably misunderstood the symbol on the ECDIS. The ship had a fully approved ECDIS. But apart from the Master the other deck officers were not trained on this subject. In an ECDIS the symbol of a wreck can be totally changed based upon the user’s choice of settings. The traditional ….. symbol of a wreck can become a screw-head ……. If the user changes the safety depth settings. This is not an INT1/NP5011/INP5020 symbol but an S52 symbol.

Masters Dream Come True

Automatic updating is a boon to the Master and for this feature alone every Master should insist upon electronic charts. It removes the weakest link in the chain of chart correction. Corrections issued from the HO can be directly applied without bringing an error-prone human in the loop.

Next to accuracy is the speed of applying the corrections. In this age of reduced manning Master can utilize the second mate for other equally important tasks on the ship.

Chart corrections usually took hours on the chart table. It can be now completed within a few minutes with the click of a button and relieve the second mate for cargo work in the port or concentrate on safe navigation at sea.

Automatic updating has helped the Master to update his charts before entering the harbour or before transiting through difficult patches at sea such as narrow straits, heavy traffic sea lanes and congested anchorages where it is critical to have the latest information. Information about a sunken vessel, a buoy adrift or dysfunctional radio beacon needs to be immediately applied on the chart.