The navigators toolchest- sight and sound

 Background

The Navigator possesses 2 personal traits that greatly enhance his ability to navigate. His eyes and his ears. Both require he or she have the highest medical standards for sight and hearing. Colour blindness is not an option if you are to be a deck officer as you must be able to distinguish between the major navigational colours of red, green and white.

The navigator is trained to identify conditions in his maritime environment. The sky, the horizon, sea surface and objects around him, all need to be analysed and translated into navigational decisions. He must be able to differentiate them by day or by night.

By day

During the day he normally has a focus on weather.

[1]

To start interpreting weather for navigation purposes, the navigator first turns to the barometer. The marine barometer[2] is quite special, not at all like the circular aneroid barometers seen on land. Instead it is a glass column filled with mercury. The scale on the side facilitates the reading of the top surface of the mercury. Atmospheric pressure controls the height of mercury in the tube. So a low pressure has a lower level of mercury and high pressure has a higher level.

The instrument is gimballed so the barometer stays relatively vertical during the motion of the ship.

[3]This is not the place for a technical discussion on weather systems. The navigators prime interested is how locally forecast weather will affect the ship in terms of wind, wave height and their direction. The changes in the barometer reading indicate to him the general status of local weather.

 Then he focuses on 2 prime features of the weather, the type of cloud and their height and the wind direction and its current tendency. With that information, he can make decisions to reduce bad weather affecting the ship.

This is very important when a winter storm or hurricane is near.

[4]The water surface by day also provides numerous navigational types of information. The swell and local waves help the navigator assess any danger to the ship's motion. Excessive rolling or pitching that can be a safety issue.

Changes in wind direction and strength help the navigator decide the most likely course to take.

By night

[5]The nighttime sky is a wonderful source of navigation items, the stars and the planets. They can be used to fix the ships position and give him also a relative course to steer by. First, he must identify these celestial bodies. The planets Saturn and Mars are easily identified in the northern hemisphere. Then there is the moon. The first star he searches for in the northern hemisphere is probably the Pole star.

Not very bright, but on a clear night observable. Its importance is that its altitude is also the ships latitude. A navigator can identify a range of stars useful for celestial navigation.

 The sea surface

[6]The presence of ships or land and navigational symbols are constantly monitored by the navigator. The horizon is a special case. It is where he first sees the approach of other vessels and land. At night, the loom

of the lighthouse often appears long before the light itself. Constantly sweeping horizon is a fundamental requirement of the watchkeeper.

Convention on the International Regulation for Prevention of Collisions at Sea (1972)

In addition to interpreting the natural marine environment, the navigator must be able to identify and interpret the actions of other users of the Maritime Highway.

The rules for this are embedded in the regulation for the prevention of collision at sea, colloquially called the “COLREGS”[7] He is trained to know each of the forty-one international navigational rules for conduct of vessels at sea. In addition, he must be able to identify each vessel on the sea and determine its actions. Is it a fishing boat, a ship not moving, is it anchored?

Vessels display symbols by day and lights at night to indicate their status. For example, the ship at anchor displays a black ball in the bow by day and a single white light in the same position by night.

The common set of light for all vessels are their steaming lights. They are white masthead lights, red port and green starboard lights and a white stern light. In addition there can be other lights and symbols denoting their current status.

Sound at sea

The navigator has a further sense he can use to effectively navigate. His hearing. A deck officer must have good hearing. Discerning sounds internally to the ship and externally and interpreting them is an essential safety element in navigation.

Externally, it can be one of many sound signals used to inform on the COLREGS. From changing direction, to abandoning ship or to announce your presence in reduced visibility, the ships whistle, or horn is an essential navigational tool. For example, three short blasts on the ships horn indicates the ships is running its engines astern.

Other ships announce their presence or their intentions with their horns or whistles. Light houses and buoys signify their presence in reduced visibility conditions with foghorns or bells.

All this helps the navigator fixes the ships position.

Internally the watchkeeper must be able to respond immediately to a range of sound alarms whether it be an equipment failure, presence of fire or flooding etc.

There is another sense important to the navigator and that is his sense of balance. A change in the motion the ship is instantly felt. Was it an intended action or is this something the navigator needs to address? It could be a change of course, the shifting wind or wave direction that is felt. Sometimes it is a combination of all these senses that alert the navigator to the changed status of the ship It could be changes in  engine noise or vibration or alteration of course that alerts the navigator to a change in the ships status.

The navigator must be constantly alert using all his senses.

References

‘123Capture.JPG (305×305)’. n.d. Accessed 31 August 2025. https://britastro.org/wp-content/uploads/2018/08/123Capture.JPG.

‘Don’t-Confuse-the-‘Loom’-of-the-Light-with-Its-“Dipping-Distance”.Jpg (800×377)’. n.d. Accessed 31 August 2025. https://keyassets.timeincuk.net/inspirewp/live/wp-content/uploads/sites/19/2015/08/Don%E2%80%99t-confuse-the-%E2%80%98loom%E2%80%99-of-the-light-with-its-%E2%80%98dipping-distance%E2%80%99.jpg.

in, You are not logged in-Log. ‘Kvikksølvbarometer’. Accessed 31 August 2025. https://digitaltmuseum.no/011024193297/kvikksolvbarometer.

‘Low Pressure Clouds - Google Search’. Accessed 31 August 2025. https://www.google.com/search?sca_esv=788002144cbb21b9&sxsrf=AE3TifN56Og6MJOGBUqjvHFQAA49VK-GbQ:1756647986743&udm=2&fbs=AIIjpHxU7SXXniUZfeShr2fp4giZ1Y6MJ25_tmWITc7uy4KIeqDdErwP5rACeJAty2zADJjYuUnSkczEhozYdaq1wZrEIDTyhM-aSQUsrB-ed3geL88JFzloJ36yIlLvNFOvrd4yvVOUa-6l0eI7rWgBT54Ag8yyO_tE6L9K_1dLOwaFTlEoj3BElHlxog-MP3Nt77kS6XXt&q=low+pressure+clouds&sa=X&ved=2ahUKEwjv8frZl7WPAxWLPhAIHY9wHVMQtKgLegQIExAB&biw=1136&bih=480&dpr=1.1#vhid=V-GEuVWkTcnKNM&vssid=mosaic.

‘Mariner’s Guide to Ocean Waves’. Weather Wisdom. Ocean Weather Services, 29 October 2015. https://oceanweatherservices.com/blog/2015/10/29/mariners-guide-to-ocean-waves/.

Organization, International Maritime. COLREG: Convention on the International Regulations for Preventing Collisions at Sea, 1972. IMO e-Publications, 2003. https://doi.org/10.62454/KB904E.

 

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[1] in, ‘Kvikksølvbarometer’.

[2] in, ‘Kvikksølvbarometer’.

[3] ‘Low Pressure Clouds - Google Search’.

[4] ‘Mariner’s Guide to Ocean Waves’.

[5] ‘123Capture.JPG (305×305)’.

[6] ‘Don’t-Confuse-the-‘Loom’-of-the-Light-with-Its-“Dipping-Distance”.Jpg (800×377)’.

[7] Organization, COLREG.

Summer ferry to Denmark

 

Summer Holidays are always welcome and especially when we go to Denmark.

The holiday really starts when you leave home and that requires planning because we are going to take a ferry from Norway to Denmark in the middle of summer, lots of people on the road. Lots of traffic.

Nevertheless, it is exciting as we pack all our goods and prepare to set off. The first challenge is. Shall we stop and have a cup of coffee on the way or are do we not have time? Must we press on because of delays on the road etc with good planning, that's not a problem, so we stop and have a cup of coffee. Very pleasant.

Then we set off for the ferry terminal and the queue starts about 3 kilometres from the ferry terminal and we join a queue. Everything gets exciting. We pay for our entry. They know all about us. Because they have the car registration number from the overhead camera and we booked online no problem. Straight into a parking lane with a ticket to let us into the buffet when we get on board.

Then the chaos starts. Once given the signal to drive onboard you join a line traffic until you've parked the car, You must remember where you parked the car. Quite important which deck, which side you go upstairs. And you look for the cafe entrance. Complete chaos. Not everybody likes the idea of queuing, so it is like a rugby scrum, pressing in to find the answer, the answer to who can help you with the finding a place. Finally, we get in there, sit down, sigh of relief. Just relax for a few minutes. But not everybody else, no, they are running round, filling their plates with food, sitting down and talking, talking, talking. Time to observe people around us. There is all sorts of people. There are groups going to music festivals, there are groups going on holiday, there are young families, there are old, there are lorry drivers. All are interested in one thing, food.

It appears something takes over when they word buffet is mentioned instead of eating sensibly and taking just enough for the period. They fill their plate repeatedly. They gorge. There is even a card on the table which says eat as much as you like but please do not waste food. That tells it all. Nevertheless, it is nice to see that there's lots of families, young families, looking after their newborn baby. Carrying all the requisite number of. carriers, changing gear that is needed. And older kids running around. Taking part in treasure hunts, etc. The start of the voyage was a little bit bumpy, a little bit bouncy, there was a little bit of wind on the bow, but as soon as we got away from the Norwegian coast, moving towards the Danish coast, it subsided.

As a seafarer, I'm extremely interested in what's happening outside of the ship. Not so people travelling on holiday in the buffet. All they are interested in is eating, talking to each other, drinking as much as they can and enjoying, which is, after all, the start of their holiday.

Happy holiday

Senior Travel revisited

 

On a package charter flight

You would think that as you get older it would be easy to travel abroad, especially if you spent a large part of your career travelling internationally.

But it does not. Why is that?

Well, your age and your physical and mental resources become somewhat diminished.

Secondly, travel procedures change. Remember how parking rules change and become confusing. Well, it's the same with flying, especially if you are on a package tour.

It starts the day before travel when you start the challenge of finding your travel gear. Where are my sunglasses? Do I need my swimming gear in the Canary Islands in February etc etc.?

You learn as your memory fails you to assemble everything in one place before packing and only then start the procedure of packing. What are the travel agent’s rules for the tour. Well, they're different from ordinary flight booking and check in procedures. No check-in details, only a booking reference number. But it is all sorted out at the airport. Passport number and booking reference number, work. Whew, what a relief! With two artificial knees, progress through security requires special attention. Off with belts, hope the trousers stay up, off with the shoes and then the indignity of the standing in a glass machine with your hands over your head, followed by a body search. So boring.

Once you have past security there is a sigh of relief.  Now we can relax, we are in the hands of the airline.

Airports are a great place to observe people, they display a microcosm of society, all waiting to depart to various parts of the world.

The young Thai couple who talk in Thai with the waiter, the Asian family that clear their table and place a tray of discarded food on the trolley. Not something we all do!

One noticeable feature is the number of people with small sacks on their back, a typical feature for Norwegian travellers.

We sit in a cafe and wait until it happens. “Go to gate!”

Immediate response. Half the cafe guests rise and saunter over to the departure gate where seating is at a premium!

We watch the gate operators keenly as they check and double check the readiness to board the aircraft. By this time the gate is surrounded by many people clutching boarding cards and mobile phones with check in details.

Then the bombshell. We will be boarded by groups A, B and C! We are Group B so expect to board as the second group, but we were the first because we are in the middle seating area of the plane.

Onto the plane with the usual queuing, bumping into people and finding your seat. Sit down and wait for the public address to announce boarding complete.

Now is the opportunity to find a vacant seat to be more comfortable by the emergency exits. No such luck, the flight is fully booked.

Once airborne, you start to look around you. Babies and children run up and down the aisles. I had an aisle seat, which I thought was wise because I can get out without disturbing other passengers in my row. What a mistake!

I was battered, bumped, hit by trolleys and by people passing down the aisle. Not a wise choice.

The ordered warm foods arrive, and it was the signal for others to remove home food from their packs and start eating. Clearly a reference to charter flight onboard food!

However, it was not too bad. Then we all settled down to the remainder of the flight. Noise cancelling headsets in place. Neck supports inflated and you take up a recumbent pose. Good. But how do you do that. Some rest their heads on the table, or they sit upright and try to go to sleep, but not everyone. Sudoku ready, reading newspapers, watching video, take out knitting, all take people's attention as we headed South at 35,000 feet to warmer climes.

The flight attendant announces there is one hour left before arrival. So, the queue for the toilet starts. Should I join it or wait. Eventually there is a gap in the queue, and you scurry forward and bounce around from one seat edge to another as you weave your way down the aisle. When you get in the toilet basin is full of grey water! Take down your trousers and try to sit on the toilet seat that requires Houdini like antics. Is it because I've gotten older or am I imagining it?

 Finally, you return to your seat, the toilets ate off limits and the plane descends, and you look out the window and see an airport full of aircraft. You land. The scramble to get baggage. And finally, out onto the concours where a lady with a large sign assembles us and lead us to a bus and we're on our holiday.

A sign says Welcome to Las Palmas. I think a siesta is what I need!

The Navigators toolbox-marine log

 

[1]

Background

The compass, sextant, chronometer, and radar are tools that fix the ships position on a chart, meaning the position is a known place “on the ground”.

The speed of a ship is another parameter important to navigation and historically has been achieved by measuring the passage of an object alongside the ship. The principle is that an object thrown overboard stays stationery as the ship moves past it. If we can measure the time it takes for the ship to pass the object, we can measure the speed of the ship. There is an important provision here. It measures distance travelled through the water not “over the ground”. Therefore the effects of water mass movement, tide and wind on the ship are not taken account of.

The structure of the log is simple. A quadrant-shaped piece of wood is weighted with lead to hold the quadrant vertical in the water. A bridle is attached to each corner of the quadrant and then to a log line that is wound on a spool. A release line is attached to one corner of the quadrant and a wooden plug secures it to the log line. A sharp tug on the log line will release the quadrant from its upright position in the water for retrieval.

Another version of the log uses a canvas drogue or mini sea anchor with the same construction.[2]

Attached to the logline is a series of

knots depicting how much line is released. The knots are placed a known distance apart, eight fathoms generally. So a double knot is the second knot on the line and signifies 16 fathoms of line are out. To mark the deployment of the log, the line is released until the first line marker is in the water. This is

usually a piece of leather or cloth.

[3]The element of time in the use of the log is supplied by a sandglass built especially for use with a log. The time to

empty the sand from the upper glass is usually 28-30 seconds.[4] So if 16 fathoms of line is run out in 30 seconds, the distance covered is 11520 feet in one hour.

[5]However the unit of distance at sea is the nautical mile defined as the distance of an arc of one minute measured on a meridian and is 6080 feet. The vessel’s speed in this example is 11520/6080 which is 1.9 knots.

Approximately 2 knots for the two knots on the logline.

[6]There were variations in distance marking of logline and the time to empty the sandglass but the principle for each ship was that the number of knots on the logline should approximate the vessels speed in knots.

 

[7]Thomas Walker was a clockmaker who turned his attention to measuring distance at sea. After much experimentation the “patent Walker log” was produced in the 1880’s.  A mechanical counter (1) was connected to a governor(2) and a braided logline(3). A rotating propeller(4) completed the assembly. The log was attached to the taffrail at the stern of the ship and was deployed on leaving port. The counter recorded distance and was read each watch and the result recorded in the ship’s logbook.

Reading of the log was usually done by a junior officer and in pouring rain and sometimes heavy seas I would struggle aft to read the log and report my findings to the officer of the watch. A miserable job!

Later models had an electrical connection to a bridge repeater, much easier.

Deploying the log after leaving port was not that simple as I found out. Thinking the best way to set it in the water was to lower the propellor into the water and pay out the logline until everything was set out resulted a set of knurled rope full of twists and knots.

You stupid boy, said the Scottish 2^nd. Mate. You pay out the line from the log first and then finally drop the rotator in the water. So much to learn “on the job”.

Nevertheless, the patent Walker log stayed an essential tool to the navigator for many decades until replaced by a rotator built into t the hull of the ship.

 

References

‘Chip Log’. In Wikipedia, 28 September 2024. https://en.wikipedia.org/w/index.php?title=Chip_log&oldid=1248278445.

in, You are not logged in-Log. ‘Logg’. Accessed 27 May 2025. https://digitaltmuseum.no/011024192632/logg.

———. ‘Logg’. Accessed 27 May 2025. https://digitaltmuseum.no/011024192629/logg.

———. ‘Logg-Glass’. Accessed 27 May 2025. https://digitaltmuseum.no/011024193987/logg-glass.

‘Nautical Mile’. In Wikipedia, 20 February 2025. https://en.wikipedia.org/w/index.php?title=Nautical_mile&oldid=1276676565.

‘Thomas Walker & Son’. In Wikipedia, 5 May 2025. https://en.wikipedia.org/w/index.php?title=Thomas_Walker_%26_Son&oldid=1289002093.

Walkers Patent Log. n.d. Norwegian Maritime Museum.

Acknowledgements

Bengt Malm, Ancient Mariner, and volunteer at the Norwegian Maritime Museum

Camilla Nordeng, conservator for artifacts at the Norwegian Maritime Museum

 

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[1] in, ‘Logg’.

[2] in, ‘Logg’.

[3] in, ‘Logg-Glass’.

[4] ‘Chip Log’.

[5] ‘Nautical Mile’.

[6] Log.

[7] ‘Thomas Walker & Son’.

The Navigators toolbox-RADAR

 

[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 19^th. century.[2] Radio Detection and Ranging (RADAR) was first used for ship detection in the early part of the 20^th. 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/.

 

 

 

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[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’.