Blue Water

The Maritime Safety Committee of the International Maritime Organization (IMO) has voted to establish new international regulations that will eventually require most cargo and passenger ships to be equipped with an approved Electronic Chart Display and Information System (ECDIS).

The new regulations are embodied in amendments to the international Safety of Life at Sea (SOLAS) Treaty and will enter into force January 1, 2011. ECDIS will be mandatory on any new ship whose keel is laid after that date, and the carriage requirement will be extended to cover existing ships on a phased schedule over the next seven years, starting with passenger ships, tankers and very large cargo ships. By 2018, all passenger ships over 500 gross tons (gt), all tankers over 3,000 gt and all other cargo ships over 10,000 gt will be fitted with ECDIS.

ECDIS products have been on the market for quite some time and are currently in use on hundreds of ships, often interfaced with radars and Automatic Identification Systems (AIS) for a composite picture that shows radar targets and ID information superimposed on the electronic chart display. Some advanced fleets have gone so far as to eliminate the use of paper charts altogether, shifting to ECDIS for route planning, navigation and piloting (this is permitted under current IMO regulations only if the ship is equipped with two independent approved ECDIS systems for built-in redundancy).

The performance standards and technical specifications for ECDIS are lengthy and detailed. All ECDIS products will have to be type-approved by an organization recognized by the IMO as a certification body (e.g., the U.S. Coast Guard).

Now that the IMO carriage requirements, standards and deadlines have been established, marine electronic manufacturers are making plans to bring new products to market in time to meet the mandatory dates. At the same time, international hydrographic offices are rushing to complete their database of Electronic Navigation Chart (ENC) coverage over the world’s major shipping routes and ports. Meanwhile, the shipping industry is coming to grips with the need to establish formal training requirements, standards and courses for seafarers to operate these increasingly complex pieces of computerized equipment.

If you’d like to know more, you can download a brief guide to the IMO ECDIS regulations here: (IMO ECDIS regulations).

In the Navy, we had an expression “gundeck,” which referred to falsifying logbooks and records after the fact. We used it as a verb – as in “to gundeck.”

As Quartermaster of the Watch, I had to maintain a number of different logbooks and records, in addition to maintaining the navigation plot on the chart. The Quartermaster’s Log contained a minute-by-minute record of everything that happened on the ship, including every change in course or speed. I also had to keep a magnetic log comparing the gyro-compass and magnetic compass at least every 30 minutes and after every course change, and detailed weather observations every hour. Sometimes, especially during high-tempo operations (for instance, when at General Quarters), I might fail to record log entries immediately as required. At the end of my watch, before being relieved, I might “gundeck the log” by adding entries after the fact. This was of course against regulations, but probably relatively benign in most cases. There’s a big difference, however, between gundecking and deliberately falsifying the ship’s records after an incident to escape culpability.

Here’s a case in point, as reported in Safety at Sea International (www.safetyatsea.net).

The MS Atlantic Eagle, a 74,086 dead-weight ton bulk carrier loaded with wheat, struck Maude Reef off Western Australia in July 2008, seriously damaging its hull, rudder and steering gear. The Australian Transport Safety Bureau (ATSB) investigators determined that for more than 40 minutes prior to the grounding the ship’s position was not charted by the bridge team. The investigators said the second mate “… had little appreciation of where the ship was or would be with respect to navigational dangers ahead.”

Now the mischief begins. The ATSB found that entries in the ship’s bridge log book had been made in pencil and included erasures, while the official deck log was completed in pen by the master at a later time. Positions on the chart were falsified. “Log books and records were then completed in a manner aimed at ensuring consistency with the chart rather than being accurate, factual and indisputable as required,” said the report.

In the future, it will be a lot harder for a watch officer to gundeck or falsify logs, as manual record-keeping is replaced by electronic logbooks. Most merchant ships today are required to carry a Voyage Data Recorder (VDR), which is similar to an aircraft’s “black box.” The VDR interfaces with the ship’s navigation and control sensors, as well as microphones on the bridge and VHF radio, and stores this data in a hardened waterproof and fireproof capsule for later retrieval to be analyzed after an incident at sea. You can download a helpful guidebook explaining VDR technology at Sperry Marine’s website (VDR technology guidebook).

If this subject interests you, I suggest you visit the Confidential Hazardous Incident Reporting Programme (CHIRP) website at www.chirp.co.uk. The aim of CHIRP is to contribute to the enhancement of maritime safety in the UK, by providing a totally independent confidential (not anonymous) reporting system for all individuals employed in or associated with all types of marine craft. CHIRP’s quarterly newsletters are filled with frank reports and commentary on collisions, near-collisions, accidents and other incidents at sea. Many of them involve the interaction of small pleasure craft with large cargo ships. 

There’s no doubt he made a series of errors, and I am sure he deserved his sentence – if for no other reason than that he lied on his license renewal forms. Still, I can easily envision myself on the bridge of a large merchant ship, unable to see my familiar visual piloting aids in the dense fog, surrounded by officers who don’t understand my language, struggling with radar and ECDIS screens that don’t seem to make sense to me and feeling awfully, awfully lonely and exposed. The sea, alas, is an unforgiving master. So are federal courts, especially when it comes to spoiled. 

Yikes! 

 

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In the interest of full disclosure, I must tell you that Sperry Marine is one of my PR clients, and I helped to write the press release on this occasion.
 
http://www.sperrymarine.northropgrumman.com/CustomPages/News/news-and-press-releases_details.aspx?id=252

http://www.sperrymarine.northropgrumman.com/CustomPages/News/news-and-press-releases_details.aspx?id=252

Nonetheless, it is very gratifying for an old salt like me to play a part in honoring one of the new generation of up-and-coming navigators, and I wish him “fair winds and following seas” as he goes from the classroom to the fleet.  

 

If you are interested in the subject, I highly recommend Dava Sobel’s best selling book on Harrison’s famous chronometer.  The book, “Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time,” was published in the mid 1990s and is still in print. You can order a copy from www.amazon.com for less than $7.00. It’s a fascinating story and well told by Ms. Sobel. 

You can read about the awards and the winners at www.marinenewswire.com. 

If you’re interested in keeping up with the latest piracy news, you can find a wealth of information at The International Maritime Bureau’s Piracy Reporting Center (www.icc-ccs.org).   

When I went to sea in the early 1970s, the state-of-the-art for maritime navigation on the open ocean was to make imprecise estimates of a ship's position through celestial observations of the sun, moon, stars and planets. Using a sextant, we would measure the angle of a celestial body above the horizon and then laboriously work through complicated trigonometric functions to translate those measurements into lines of position on a plotting sheet — often an hour or more after the sight was taken. Between celestial fixes (which could be several days) we used dead reckoning to estimate our position.

I got a thrill out of pacing the bridge wing at dawn and dusk with a sextant, stop watch and starfinder, trying to pick out Sirius, Kochab or Alpheratz. I felt an almost mystical bond with the ancient Arab astronomers and mathematicians who first figured it all out back in the Middle Ages.

Now, of course, we still look to the skies for guidance. But instead of the stars, we use radio signals from satellites to fix our position on the earth's surface. While I still feel a certain level of nostalgia for the "bad old days" of celestial navigation and dead reckoning, it's undeniable that marine electronic GPS has made a tremendous difference in maritime navigation and an inestimable contribution to safety at sea. Electronic GPS provides a real-time, constantly updated, highly accurate ship's position, liberating the navigator from the need to plot fixes and dead reckoning tracks onto paper navigation charts. Electronic GPS is the fundamental enabling technology that permits us to navigate on C-Map electronic charts.

So how does GPS work? I hope you won't mind if I oversimplify what is actually a very complicated process. Basically, a GPS receiver calculates its position through triangulation — that is to say, by crossing three or more lines of position. Each GPS satellite transmits a radio message that contains both its position in space and a super-precise time signal. The satellite signal is transmitted in a form known as a pseudorandom code and a GPS receiver generates an identical pseudorandom code. By matching the received code with its own generated code, the GPS receiver is able to determine the distance to each satellite. It does this by measuring the elapsed time it takes the signal to transit from satellite to receiver. (The radio-wave signal travels at roughly the speed of light — 186,000 miles per second.) With three satellites, you can thus determine your position in two dimensions, which is fine for surface navigation. With four or more satellites, you can compute a three-dimensional fix. (The fourth signal yields altitude.)

In my next blog, we'll look at GPS errors and how they can be minimized through differential techniques.

In the meantime, you can read a good tutorial on basic principles of GPS on the Trimble website at www.trimble.com/gps/howgps.shtml. Trimble was originally a pioneer in electronic navigation instruments, but has since given up its marine navigation business in favor of highly precise GPS-based surveying technology.

You are the officer of the watch. It's a dark night. You are tracking a dozen or more targets on your marine radar system. One of the blips on the radar screen seems to be turning to its right. You pick up the VHF microphone and check to see that it is set for the correct hailing channel.

"Vessel on my starboard bow, this is MV Eversail. It appears you may be making a turn to starboard. Do you intend to cross my bow? Over."

"Eversail, this is MV Seafarer. Are you the ship in the inbound lane near buoy 23? Over."

"Seafarer, this is Eversail. That's a negative. I am at the junction buoy near Deadman's Reef. Over."

"This is Seafarer. Roger out."

Silence...

"Eversail, this is MV Oceanbreeze. I think I am the vessel off your starboard bow. I am outbound in the auxiliary channel from the tanker berth. I am slowing to disembark the pilot. Over."

"Oceanbreeze, this is Eversail. I have you on my radar. You are not the ship I was calling. Over."

Silence...

"Vessel five miles off my starboard bow, this is MV Eversail in the outbound channel passing Deadman's Reef Junction Buoy. What are your intentions? Over."

"Eversail, this is MV John Brown. I think I am the vessel off your starboard bow. Over."

"John Brown, this is MV Seafarer. I believe I am astern of you. Are you the ship that's just passing Buoy 23? Over."

And so forth...

Radio exchanges like these are a common occurrence on ships at sea, especially when transiting a busy shipping lane. All ocean-going ships are required to carry collision-avoidance marine radar systems that automatically plot course and speed vectors for targets being tracked. The weak link, however, is the inability to identify any given radar target on the screen when multiple contacts are being tracked. This is especially true at night or in reduced visibility when it is impossible to verify a ship's identity visually.

Which blip belongs to which ship? This is one of the most confusing areas of sailing navigation. And this inevitable confusion is a contributing factor in many collisions and near-collisions at sea.

A new technology called Automatic Identification Systems (AIS) helps to resolve this difficulty by providing a means for ships to exchange ID, position, course, speed and other vital data with all nearby ships and shore stations through a standardized data transponder.

The AIS concept derives from the pioneering work of Swedish inventor Hakan Lans, who developed a scheme called Self-Organizing Time Division Multiple Access (STDMA). This scheme permits a large number of transmitters to send data bursts over a single narrowband radio channel by synchronizing their data transmissions to a precise timing standard. In the case of AIS, the timing signal derives from GPS.

The Safety of Life at Sea (SOLAS) treaty requires ships over 300 gross tons, that are on international voyages, to be equipped with an approved AIS transponder. In addition to ship-to-ship reporting, AIS can be used for ship-to-shore and shore-to-ship transmissions. A number of nations in the European Union are constructing inland AIS-based infrastructure to monitor movements of vessels on rivers and canals. Many coastal nations also are establishing automated AIS networks of shore stations for surveillance of ships sailing through their coastal waters.

A new standard called AIS-B recently has been developed for voluntary installation on smaller vessels that are not subject to the SOLAS carriage requirements. AIS-B is designed for private fishing boats, pleasure boats and the like.

The new generation of marine radar systems frequently has built-in capability to overlay AIS data on the radar picture. Thus, the vessel's ID, course, speed and other data are shown as a tag or in a separate window for each AIS target.

If you're interested in learning more about AIS, you can find a great deal of useful information at the U.S. Coast Guard Navigation Center. www.navcen.uscg.gov/enav/AIS/default.htm  Another good resource is Saab Transponder Tech, the company that did much of the pioneering work in AIS technology in the late 1990s. In 2008 Saab was one of the first companies to introduce an approved AIS-B transponder for smaller craft. www.saabgroup.com/en/AboutSaab/Organisation/SaabTransponderTech/News.htm 

Let me tell you how I learned about datums.

But first, to all the sharp-eyed Latin scholars out there, yes, I did say "datums" and not "data." For some unknown reason when talking about cartography, the plural of datum is datums.

I was keeping the navigation plot on the morning watch as my ship steamed from one set of islands to another in the Caribbean. Our route plan called for us to arrive off the sea buoy just about daybreak. There was a thick morning mist across the water. As we made our approach using radar, I shifted our plot onto a larger-scale chart. Suddenly our dead-reckoning position appeared to jump a quarter mile on the new navigation chart. I discovered that the entrance buoy was on our starboard bow instead of our port bow. We reversed engines and narrowly escaped running aground.

That's when a red-faced captain explained datums to me in extremely colorful language that could only be described as "salty" and I learned an important lesson.

So what happened? The two navigational charts used different datums and the error between the two added up to more than 500 yards!

Let me explain. The datum defines the frame of reference used to create a navigation chart's coordinate grid.

The latitude and longitude coordinates of charted objects are based on hydrographic surveys. A survey starts with a control point — sometimes referred to by surveyors as the "point of beginning" or POB. Once the control point is established, the surveyors can plot the coordinates of other charted objects relative to the POB. (When I first went to sea, we did this using horizontal sextant angles and a three-arm protractor. Now it is done with highly accurate differential GPS.)

The mathematical models that the cartographer uses to depict the irregular ellipsoidal 3-D shape of the earth's surface on a 2-D surface also determine the local datum of a navigational chart. There are hundreds of local and national datums. They have names such as the North American Datum of 1927 (NAD27), the Australian Geodetic Datum of 1966 (AGD66) and so on.

When sailing in local waters, the navigational charts of the region normally use the same datum, making them consistent with one another. But as I discovered the hard way, errors can occur when shifting charts. That is why when navigators switch from one navigational chart to another, they do not simply re-plot the latitude and longitude coordinates; they re-plot the last fix using the actual compass bearings or radar ranges.

The advent of marine GPS made it possible for the first time to establish a worldwide frame of reference for reconciling local navigational chart datums. GPS positions are computed in the World Geodetic System of 1984 (WGS84) datum. When plotting GPS coordinates on paper navigtional charts, it is imperative to verify the navigational chart's datum. If it is not WGS84, you may need to apply conversion factors. Most modern GPS receivers are able to perform the conversion automatically through a datum-selection function.

Jeppesen Marine bases its electronic charts on a vector database calibrated to WGS84, but some raster charts and vector charts that were created by digitizing paper navigational charts may still be based on the local datum. So it is a good idea to check the datum on your navigational charts, just to be sure.

To learn more about datums, visit the datum home page of the U.S. National Geospatial Intelligence Agency at www.ga.gov.au/geodesy/datums/aboutdatums.jsp

When I first went to sea some 40 years ago as a young petty officer in the U.S. Navy, one of my primary responsibilities was to keep the ship’s navigational charts and nautical publications up to date. The navigation charts encompassed a portfolio of several hundred paper charts while the nautical publications included a bookshelf crammed with navigation guidebooks like International Sailing Directions and U.S. Coast Pilots. The corrections to these were made by pen-and-ink, using information derived from the weekly Notice to Mariners. I had to maintain a card file that recorded which changes had been made to which charts — a tedious and time-consuming job! 

Keeping navigational charts up to date is a never-ending process. Every week around the world hundreds of buoys, lights and daymarkers are created, destroyed, moved, renumbered and altered. Channels are dredged and sometimes rerouted. Underwater reefs and shoals are identified. New wrecks are discovered. To keep maritime navigation safe, all of these corrections must be marked on the appropriate navigation charts.

Thanks to scientific advances, many ocean-going ships are equipped with modern electronic charts display and information systems (ECDIS). However, the international Safety of Life at Sea (SOLAS) regulations still require these ships to carry a complete portfolio of up-to-date paper charts covering their shipping routes and ports of call. National Coast Guards vigorously enforce these regulations. Under some circumstances, ships equipped with dual redundant ECDIS may be allowed to go “paperless,” but only a handful of ships meet this requirement. 

ECDIS offers mariners the advantage of being able to download data from the Notice to Mariners through a satellite link directly into the ship’s ECDIS computer. All changes required to navigation charts are incorporated automatically into the ship’s database for display on the screen. Ease and accuracy are two significant benefits of this process. Still, every week second mates on commercial ships have to sit down in the chartroom and correct paper nautical charts with pen and ink to meet international requirements and ensure their ships’ safety.

The need for up-to-date marine maps certainly is not limited to naval and commercial ships. It applies to vessels of all sizes and types, including those of the weekend sailor, powerboat cruiser and sport fisherman. Navigating on out-of-date navigational charts poses a significant danger for every vessel and its crew. It is akin to driving blind.

Bottom line? The wise sailor makes sure that he or she has the latest and most advanced electronic charts on the water. One smart solution is marine cartography from Jeppesen Marine. The company releases new cartography twice a year for its light marine products, providing the most current, accurate navigational charts available for sailing, cruising and fishing ocean or inland waters.

For more information on how charts are updated, visit the NOAA website at http://www.nauticalcharts.noaa.gov/mcd/learn_chartupdate.html