Saturday, April 25, 2009

Tech Traps

Whenever I find myself in a teaching role, such as with a cadet at sea
or on a schooner full of students interested in learning navigation I
usually start the lectures off by recapping the 4 greatest advancements
in marine navigation according to myself. 

First and most importantly I discuss the marine chronometer and time
zones. A clock robust and accurate enough to be taken to sea and keep
track of time is something we easily take for granted but it was not
always so. This piece of navigational equipment is necessary to
determine where any celestial body should be at any given moment of the
day. Whether it was a J. Harrison original of yesterday or the oft tax
deducted Rolex of today, the marine chronometer and the ability to
determine longitude is a pillar of navigation.

No longer having to make an educated guess about how far one had
traversed an ocean in an easterly or westerly direction the second
advancement allowed navigators to make landfall in the middle of the
night without having to swing a lead line or wait for a cannon's echo
off some fog shrouded headland. Marine Radar provides a reflective
picture of our surroundings for dozens of miles. This not only aids the
navigator with very reliable position fixing ranges but also allows for
the assessment of collision risks with other vessels.

Third, and arguably the most extraordinary advancement was that of the
Global Positioning System made possible thanks to the 24 satellites sent
into orbit by the United States Department of Defense. This satellite
"constellation" now provides any aircraft, ship or person with a GPS
receiver to have very reliable, within a few meters, latitude, longitude
and altitude information. For the maritime user we are most concerned
with the course over ground and speed over ground our vessel is making
which the receiver gives in addition to our position. Furthermore, the
GPS also provides the universal time in hours, minutes and seconds
meaning that the lazy second mate never need worry again about
chronometer error.

The last and most recent revelation in marine navigation is that of the
Automated Identification System which now provides us with detailed
information for any vessel, shore station or buoy equipped with an AIS
transmitter. This new system gives the navigator much more information
about a target vessel than provided by navigational lights and day
shapes or radar. The true course, speed, position, call sign, cargo and
number of souls onboard are just a few things listed.

Before the advent of radar when assessing the Risk of Collision with a
nearby vessel the navigator relied on navigational lights at night and
bearing drift or visual relative motion. After the radar scope came into
the picture a ruler and grease pencil could be used to draw a plot to
determine the closest point of approach with danger targets. This
calculation performed by hand was time consuming and prone to
inaccuracy. If not done quickly and carefully, something I realized
firsthand when running the deck of a tall ship and trying to keep and
eye on students and off of the rocks, was eventually automated. The
development of ARPA or Automatic Radar Plotting Aids meant that with the
click of a button the target is tracked and the collision information of
the vessel is calculated and displayed on the radar screen.

By determining the closest point of approach and time of CPA the
navigator now can apply the International Collision Regulations early
and with accuracy. Unfortunately it was common that one vessel oblivious
to the risk of collision, such as a head on situation when both vessels
are required to alter course, would never answer the radio. Even after
repeatedly reading their true course, speed and your vessel's position
relative to theirs over the radio, or as the navy prefers, relative to
themselves (Something they have improved on)they would be inexplicably

A situation which required cooperation from an approaching vessel that
refused to pick up the VHF puts the observant navigator in a sticky
situation. With AIS the likely hood of not having bridge-to-bridge
communications has been greatly reduced. A ship is much less reluctant
to answer the radio when you are calling them by name; one of the many
pieces of information included in a Class A AIS target's expanded data.

With each development in navigational technology, and there are many
more than mentioned here, the risk of miscalculating a position or a CPA
is reduced. It makes seafaring a safer and more efficient business. But
with each advancement the convenience the equipment provides can
potentially reduce the vigilance always needed from a watch officer.

GPS is a prime example of this. Instead of having to use long trusted
methods to fix one's position in open ocean or confined waters the
navigator no longer needs to retain these skills. Instead a reliable fix
is attained by reading out the latitude and longitude from the GPS at
anytime anywhere in the world. Convenient? Sure. Accurate? Yes. But does
it generate a reluctance to identify different lighthouses as landfall
is made or locate buoys on the radar in search of a channel's entrance?

When it comes to over reliance on GPS I always think about a mate I
worked with a few years back. One very clear night when steaming
eastward in the Mediterranean he found himself in a panic after sighting
hundreds of lights popping up over the northern horizon as we were
headed for the Suez Canal. The radars were completely blank at the 24
mile range so he called the Captain after suffering much doubt. A few
minutes later the old man rushed up to the wheelhouse, cigarette in
hand, and had a look out the window and then slowly walked over to the
chart and confirmed what he already knew. He informed the third mate
that the lights he was seeing were those of Corsica and promptly retired
a little less confident in his officer's abilities.

Had the mate actually studied the chart and not just blindly put down
GPS fixes every hour than he might have realized that he was only thirty
miles off the island's coast and closing. The combined height of the
vessel's bridge and the hills of Corsica meant that the navigational
lights onshore followed by the lights of villages became increasingly
visible over the course of the watch. Ranging out on the radar would
have saved him considerable embarrassment the next morning at breakfast.
Unknowingly making landfall is one example of the complaisance
technology which does it all for you can breed.

AIS can also lead to this same issue. I recently came up to the bridge
for my watch as we were just passing through the last leg of the traffic
scheme separating England and France. The radar was full of targets as
expected but not a single target had been plotted with the ARPA. Instead
both radar, the 10 cm and the 3 cm, had the AIS target function enabled.
This provided information for ever vessel carrying AIS but no data for
the cluster of fishing just outside the scheme and intent on crossing
it. Rather than taking over the watch with a firm handle on the smaller
targets intentions I had to form my own opinion after waiting the two or
three minutes for the ARPA to calculate the target's data loosing time
to make an informed move in a crowded traffic lane.

In this case the third mate was depending on only one means of
determining risk of collision and it only applied to vessels equipped
with AIS. It also meant that the radars were completely out of tune
since he no longer needed to worry about a good picture to pick up the
smaller unequipped targets which he essentially ignored. I have yet to
see something in the standing orders where a mate is required to not
rely solely on the AIS for collision avoidance but it wouldn't hurt.

Now I'll be the first to admit that I've strayed into wonkishness yet
again but I feel compelled to relay my concerns of technology trumping
situational awareness. I hope this might serve to remind some of the
sailors out there, most importantly myself, to keep the other seldom
used tools of our profession sharp, even if you're lucky enough to have
electronic charts and a voyage management system to guide you along the

As Captain Bligh put it so long ago;

"As an officer and a Navigator I have ever looked with horror on neglect
and indolence, and have never yet crossed the Seas without that
foresight which is necessary to the well doing of the voyage..."
("Bligh", Gavin Kennedy, Duckworth 1978, p131.)


  1. i'm a big fan of rulers and lead pencils m'self. great posting deep water sailor, as usual.

  2. Here's a cautionary story along these lines, the upshot being an embarrassing grounding witnessed by hundreds of affected passengers, not to mention USCG etc., thanks to disconnected GPS antennas, followed by a voluminous NTSB report:

    "This report examines the following major safety issues: performance of the Royal Majesty’s integrated
    bridge system and the global positioning system, performance of the Royal Majesty’s watch officers,
    effects of automation on watch officers’ performance, training standards for watch officers aboard vessels equipped with electronic navigation systems and integrated bridge systems, and design,
    installation, and testing standards for integrated bridge systems."

    Well worth reading. though I suspect this incident is already famous amongst professional mariners. You'll need to be patient with the weirdly slow NTSB download speed.

  3. Thanks Doug. I actually just read a great article which used the Royal Majesty as a case study of this phenomenon. It was in Professional Mariner by an instructor at the USCG Academy named Lt. C. Allen. He makes a great point about the challenges of training new cadets to be prepared to handle the newest technologies while reinforcing the importance of traditional watch keeping skills.

    I for one know how easy it is to rely on the computer to take my ship across the ocean. I no longer need to adjust the autopilot, not even when great circling. I just dial in the waypoints and let her go for three or four thousand miles, and this is using technology developed the year before Royal Majesty missed her waypoint and grounded.

  4. Great post as always on the great technologies available to us and the dangers inherent in them.

    Cheers & smooth sailing.


  5. Good post. Powerful tools intended to aid us in obtaining situational awareness can sometimes seduce us into thinking we understand the situation when we do not.