Trincomalee and tea

 

Last port of call

Half full of jute from Chalna we were now approaching Trincomalee on the east coast of Ceylon to fill up with tea. This could be exciting.

Outward bound we had been in Colombo for a few weeks, both at anchor waiting a berth and then in port. It had been one of the most enjoyable port visits on the voyage, not least because of the opportunity to meet people ashore especially good-looking girls in the swimming club.

[1]                                                                                                                       

     Now we were to enter one of the largest and safest harbours in the Indian Ocean, Trincomalee on the east coast of Ceylon (now Sri Lanka). Having been fought over by many European maritime nations because of its strategic location it was now a naval and commercial port run by the navy.

The immaculately dressed naval pilot arrived even wearing white gloves, now a little soiled after climbing the pilot ladder to be greeted by our Captain who, surprisingly was also immaculate. Not an aertex singlet to be seen!

Well, Captain, we are taking you to an anchorage so you can load tea directly from barges. This did not sound too good, no shore leave, well well.

We anchored in a large bay with a sandy beach behind which was a tropical jungle where even with the naked eye you could see monkeys jumping in the trees.

There is a club on the beach, said the pilot, that is available to you to relax whilst you are loading. This sounded a lot better, I thought. Who knows who we will meet.

We anchored in 20 fathoms and laid back on the anchor until it took hold. Right laddie, said Jock, the second mate, we need to find some transits for our position. Transits, what are they, I innocently asked. You stupid Yorkshire boy, they are a simple way to check that we are not dragging the anchor and you will need them as you will be doing the night anchor watch alone! What alone on the bridge! Yes, said Jock and we need both daytime and night-time transits. So patiently he took me through the process.

[2]A transit bearing is when two fixed objects are in line. They will have a transit bearing only when they are in line. So we need to search for such objects now that we are stationery at anchor. They need to be visible day and night to the naked eye and fixed on the chart. We need at least two, better three such transit bearings to fix our position. We also need to keep in mind that the vessel swings with the tide and there can be some variation in the chosen bearings. Only experience will tell you whether it is because of the ship swinging with the tide or that we are dragging our anchor. That will keep you on your toes on the night watch!

So we searched around the coast and found some good transits, church spires with prominent hills, lit buoys with lighthouses, all on the chart.

OK, draw them on the chart and note the bearing and then check with the gyro bearing compass and report back. Dutifully did that and then came the examination! Was there a difference between the bearing on the chart and that you took with the gyro compass. Yes, I replied. OK why is that Jock pressed me for an answer. Luckily, I had spent some time with my correspondence course which normally was incomprehensible to me but on coastal navigation I seemed to grasp it.

The bearing on the chart is a true bearing and the difference with the gyro is the compass error. Good he replied and what if you had used a magnetic compass? It still would be the compass error, I replied made up of variation because the magnetic pole is not at the true north pole and deviation because of the local magnetism of the steel ship. Before he could ask another question, I said, and variation can be found in the compass rose on the chart. Wow, replied Jock, not such a numb skull after all!

[3]

So started a couple of weeks whilst barges came and went and loaded chest after chest of tea whose fragrance pervaded the whole ship. Best of all we were put on night anchor watches and mine was midnight to 06:00 leaving me free in the afternoons. This a dream job, very little to do on night anchor watch, hanging over the wing of the bridge to catch what little wind there was and check the transit bearings from time to time. A little anxious when we swung with the tide as the transit bearings came out of line a little. Were we dragging anchor or was it just the natural catenary of the anchor chain changing position. Apart from that I just dreamed of those girls at the Colombo swimming club. What lucky chap was chatting them up now whilst I was stuck at the other side of the country!

The Chief officer said we would put the motor lifeboat in the water for runs ashore and to teach the apprentices small boat handling. This was going to be fun. Of the four lifeboats we had only one had an engine and this was lowered from its stowed position to the embarkation point on the boat deck and we

scrambled in. Once in the water the chief officer decided a run ashore to the club on the beach would be an excellent introduction to small boat seamanship. You need to know that the lifeboat was like a giant bathtub and handled like one so manoeuvring was not easy but slowly we mastered the basic actions and were rewarded by a beer on the veranda of this club that seemed remarkably deserted except for the hundreds of monkeys racing through the trees.

[4]Some days we tried to water-ski in the harbour on the chutes made to contain water escaping onto the tea barges behind the lifeboat. This was not very successful as soon as we stood up the lifeboat did not have enough power to keep us up and we gently subsided into the water again. A lot of fun anyway.

Far too soon the hatches were battened down and chippy started wedging the hatch covers and the tea exporter gave us all a small tea chest of orange pekoe tea and we left that lovely harbour and started our voyage back over the Indian Ocean to Aden.

The southern tip of Ceylon is renowned fishing grounds, so we needed to keep a good lookout for the small wooden outrigger boats that fished well offshore and were difficult to spot especially at night as not all of them displayed any sort of light.

This area is also known for the concentration of whale sharks especially in February and March and they are slow swimmers so avoiding them is imperative. So visual lookout was a prime job for us junior apprentices.

Once we cleared Ceylon and entered the Indian Ocean, Jock turned to me and with a broad smile and said, now laddie we have 10 days of ocean voyage in relatively calm seas, time for you to start learning Celestial Navigation. I was dreading this as quite apart from the practical work of using a sextant that I felt competent at, the notion of mathematics and trigonometry left me quite numb. I was bottom of the bottom class in my year at school for three years running for maths. All those X’s and Y’s and negative numbers meant nothing to me!

Let us keep it simple and concentrate on the “noon sight” to find latitude and longitude. You do know what latitude and longitude is? You have used them on the chart so what if we do not have any coast, only sea and need to find our position?

So we have the sun, and we know it rises in the east and sets in the west every day. At a precise time every day it reaches its zenith, its highest altitude. This time we will call local noon for wherever we are. Greenwich in the UK is the prime meridian where longitude is zero degrees, and the time zone is called GMT (Greenwich Mean Time).

Now we know the earth rotates 360 degrees in 24 hours, one day. So that means it moves at 360/24= 15 degrees of longitude per hour. How can this help us? With an accurate clock, that’s how and we have two chronometers thanks to [5]John Harrison, a Yorkshireman in 1730. He invented a clock that could keep accurate time even at sea with all the movement of the ship. We have two and we check their accuracy every day against the “Greenwich radio pips” and note any error. They are adjusted to keep Greenwich time wherever we are in the world. Savvy so far?

So we get an accurate chronometer time for the time the sun is at its zenith for our position. We then use our Nories Nautical tables to find the time the sun reached its zenith at Greenwich, the prime meridian (0 degrees). So now we have the times for noon at Greenwich and for our position. The difference between them is converted to longitude at 15 degrees per hour to give us our approximate longitude. It is only approximate because it is difficult to measure the exact altitude for the zenith as the sun moves ever so slowly as it passes through noon. Nevertheless it can be accurate within 15 nautical miles, enough out in the ocean.

So now we need to calculate latitude for the same time. We can do this with our noon sight also. The altitude of the sun at its zenith means it is on our meridian of longitude, due south or north, and it becomes relatively easy to measure its declination. The suns declination is the angular distance of the sun north or south of the equator and we can read its value from our nautical tables for precisely this time. You will remember that the sun wanders north and south in the year because of its tilt axis between the winter solstice when there is the shortest day and the summer solstice when there is the longest day in summer. We need to know the angular distance when the sun is directly overhead, the zenith distance. This is simply 90 degrees minus our observed altitude. Latitude is then a matter of arithmetic.

If the declination and approximate latitude are in the same hemisphere and the latitude is greater than the declination, we add the zenith distance to the declination.  For the same hemisphere if latitude is less than declination, we subtract the declination from the zenith distance. If latitude and declination have different names, we subtract declination from the zenith distance.

OK, I see your eyes are glazing over so enough for now but every noon sight you can calculate our approximate position alongside us.

Go and find our approximate position from the start to be sure what hemisphere we are in and find the declination for today from your pristine new [6]Nories tables. Also find the table for converting time to longitude and the time of meridian passage at Greenwich.

Steaming northwest across the Indian Ocean you also cross a much older traditional trading route between Africa and the Arabian Gulf and we often saw sea-going dhows on passage. A refreshing sight.

References

‘Bossoir_a_gravité.Jpg (960×1280)’. Accessed 9 April 2023. https://upload.wikimedia.org/wikipedia/commons/7/77/Bossoir_a_gravit%C3%A9.jpg.

‘Chronometer Watch’. In Wikipedia, 10 August 2022. https://en.wikipedia.org/w/index.php?title=Chronometer_watch&oldid=1103608912.

‘OLD EDITION Norie’s Nautical Tables’. Accessed 19 April 2023. https://www.imray.com/product/old-edition-nories-nautical-tables/ib0095-1/.

Small crates and tea chests. ‘Small Crates and Tea Chests’. Accessed 8 April 2023. https://farthinglayouts.blogspot.com/2015/04/small-crates-and-tea-chests.html.

‘Transit Bearings - Google Search’. Accessed 7 April 2023. https://www.google.com/search?q=transit+bearings&tbm=isch&chips=q:transit+bearing,g_1:navigation:4C6g_BECbgg%3D&hl=en&sa=X&ved=2ahUKEwiAzo_835f-AhWWxyoKHWWvDpkQ4lYoAHoECAEQJg&biw=1501&bih=686#imgrc=HEjzrQFdswtcsM.

‘Trincomalee: India’s Call’, 27 April 2017. https://www.vifindia.org/article/2017/april/27/trincomalee-india-s-call.

 

---

[1] ‘Trincomalee: India’s Call’, 27 April 2017, https://www.vifindia.org/article/2017/april/27/trincomalee-india-s-call.

[2] ‘Transit Bearings - Google Search’, accessed 7 April 2023, https://www.google.com/search?q=transit+bearings&tbm=isch&chips=q:transit+bearing,g_1:navigation:4C6g_BECbgg%3D&hl=en&sa=X&ved=2ahUKEwiAzo_835f-AhWWxyoKHWWvDpkQ4lYoAHoECAEQJg&biw=1501&bih=686#imgrc=HEjzrQFdswtcsM.

[3] ‘Small Crates and Tea Chests’, Small Crates and Tea Chests (blog), accessed 8 April 2023, https://farthinglayouts.blogspot.com/2015/04/small-crates-and-tea-chests.html.

[4] ‘Bossoir_a_gravité.Jpg (960×1280)’, accessed 9 April 2023, https://upload.wikimedia.org/wikipedia/commons/7/77/Bossoir_a_gravit%C3%A9.jpg.

[5] ‘Chronometer Watch’, in Wikipedia, 10 August 2022, https://en.wikipedia.org/w/index.php?title=Chronometer_watch&oldid=1103608912.

[6] ‘OLD EDITION Norie’s Nautical Tables’, accessed 19 April 2023, https://www.imray.com/product/old-edition-nories-nautical-tables/ib0095-1/.