[1]
Background
Technology has been central in the development of new tools
for the ship’s navigator and RADAR, the
fourth in this series of articles, is a classic example. However it had one
major advantage over the earlier tools, it did not require visibility for the
navigator to see and identify objects. It could see in the dark and in dense
fog, a major benefit for the navigator. It is also one of the newer tools in the navigators toolbox
having been developed in the late 19th. century.[2]
Radio Detection and Ranging (RADAR) was first used for ship detection in the
early part of the 20th. century. Its ability to detect metal objects
by returned radio waves from the object was the basis of the modern marine
radar.
In the early 1960’s I was a newly qualified third officer
responsible for the 8-12 watch on the bridge and had a brand new Radar
Observers Certificate. The scenario was one that is stressful for a navigator,
to say the least!
Friday night in the Dover Strait in summer with thick fog and
a moderate gale! Could not be worse as in addition to the usual commercial
traffic there would be recreational boats probably caught by the weather.
This was the time to demonstrate my prowess at radar
plotting. We had lookouts on the wings of the bridge, and we were at reduced
speed and the foghorn on with the Captain on the bridge.
The visibility was about a hundred yards,
and we relied on fog signals to narrow down where a likely ship would come
from. For recreational boats we just hoped they had metal radar reflectors on
board that might be picked up by our radar.
The Radar was on the port side of the bridge with a small
table forward of it.
[3][4]So out came a blank radar plotting sheet and I went to the radar. In the 1960’s marine radar was quite basic. The screen was protected by a rubber hood that you must peer through to see the screen and the screen was green with a rotating line showing the rotation of the antenna. One of the challenges was to identify proper ship and small craft echoes from what is called “clutter”, radar echoes from waves and other objects. The problem was that clutter was most dense, hiding real echoes closest the screens centre, i.e. our ship and therefore the most dangerous area relative to the ships position.
There you were constantly adjusting the cluster control seeking clearer radar images. The radar screen was aligned with the ships head so all “hits” were going to be plotted relative to the ships course, a relative bearing and most important a distance from the ship using the radar range circles on the screen. The range of the radars horizon could be adjusted and for close water work as we had that day, 3, 5 and 10 nautical miles were the most obvious ranges to monitor.
Once a radar image is identified on the screen its relative
bearing and range was measured and transferred to the plotting sheet. You then
needed to wait some minutes before plotting the image once again. This gave you
some important information. The line joining the two plots is the relative
motion of the target and it indicates how close and what direction the target
will close your own ship. No change in the relative bearing indicates you have
a potential collision situating and the relative collision regulations need to
be applied when necessary. If the relative bearing is increasing or reducing it
indicates how the target will pass you and you can calculate the nearest approach
from this plot.
Now image multiple plots needing to be assessed and you have
a heavy workload. Improper plotting and/or too much reliance on the information
from the radar can lead to what has become called “radar assisted collisions
and that of the collision of the “Stockholm”
and “Andrea Doria” in 1956 is considered
the first of its kind.[5]
The basic rule is to use the COLREGS in sufficient time with
sufficient effect that can be observed by the other vessel.
So back to the Dover Strait and my radar plotting. I duly
reported the situation from my radar plots to the captain to be sternly
reprimanded. “Third mate, get your binoculars and keep a watch on the wing of
the bridge and stop using that new fangled instrument”! Duly chastised I
followed orders.
There is a moral to this story that new technology can be
implemented relatively quicky but us humans take time to adjust to them.
Thankfully, marine radar has advanced enormously since those
times and as ARPA (Automatic Radar Plotting Aid) is now an integral part of
electronic navigation.
References
Clipper. Français :
Feuille de Plotting Radar Au Format A3. 19 September 2017. Own work.
https://commons.wikimedia.org/wiki/File:Radar_plotting_sheet_A3.pdf.
‘Collision of the Liner Stockholm and the
Andrea Doria on 25 July 1956 In heavy Fog’. Accessed 3 May 2025.
https://www.splashmaritime.com.au/Marops/data/less/Colreg/Casualties/Stockholm%20and%20Andria%20Doria.htm.
‘History of Radar’. In Wikipedia,
21 April 2025.
https://en.wikipedia.org/w/index.php?title=History_of_radar&oldid=1286767003.
‘Poster Ship Radar Screen or Military
Sonar Digital Display with Vector Targets and Submarine Traffic Tracks,
Nautical Navigation Technology – Veggbilde | Europosters’. Accessed 27 April
2025. https://www.europosters.no/ship-radar-screen-or-military-sonar-digital-display-with-vector-targets-and-submarine-traffic-tracks-nautical-navigation-technology-f534014831.
‘These Three Pieces of Marine Electronics
Forever Changed the Course of Boating. | Yachting’, 4 September 2015.
https://www.yachtingmagazine.com/big-three/.
[1] ‘Poster Ship Radar Screen or Military Sonar
Digital Display with Vector Targets and Submarine Traffic Tracks, Nautical
Navigation Technology – Veggbilde | Europosters’.
[2] ‘History of Radar’.
[3] ‘These Three Pieces of Marine Electronics Forever
Changed the Course of Boating. | Yachting’.
[4] Clipper, Français.
[5] ‘Collision of the Liner Stockholm and the Andrea
Doria on 25 July 1956 In heavy Fog’.
