Tag Archives: VOC

A large, high-lying land

Abel Tasman banner

On December 5th 1642 Tasman and his Council decided that since the wind direction would no longer allow them to follow the coast of Tasmania, they should turn East.

“we could no longer steer near the coast here, seeing that the wind was almost ahead. We therefore convened the Council and the second mates, with whom after due deliberation we resolved, and subsequently called out to the officers of the Zeehaan that, pursuant to the resolution of the 11th ultimo we should direct our course due east…

… we then shaped our course due east for the purpose of making further discoveries”

Abel Tasman's path across the Tasman Sea

Abel Tasman’s path to December 13th

For the next seven days Tasman sailed east, and his journal includes only the day’s weather and his routine report of; position, course kept and distance sailed. On Dec 12th he recorded that he was not expecting to find land as he was experiencing open ocean swells.

“The heavy swells continuing from the south-west, there is no mainland to be expected here to southward”

In this, he was wrong. There isn’t land to the South-west of his position on that day, but there is land to the South, and he was much closer to it than he suspected.

Abel Tasman's path across the Tasman Sea

Abel Tasman’s path to December 13th

His journal for the following day began routinely, reporting his observed latitude, estimated longitude, and the weather. However, it continued…

“Towards noon we saw a large, high-lying land, bearing south-east of us at about 15 myles distance”

On December 13th, 1642 Abel Tasman and his crews saw New Zealand, and Tasman wrote the words “Groot in hooch verheven Landt’… ‘a large, high-lying land’ in his journal. Abel Tasman, his journal, both vessels and most of the crew survived the voyage. Copies of journal still exist, making theirs the earliest validated European discovery of New Zealand.

This is the complete Journal entry for December 13th, 1642.

The page from Abel Tasman's journal including the entry for December 13th

The page from Abel Tasman’s journal including the entry for December 13th

“13th December”

Latitude observed 42° 10′, Longitude 188° 28′; course kept east by north, sailed 36 myles in a south-south-westerly wind with a top-gallant gale. Towards noon we saw a large, high-lying land, bearing south-east of us at about 15 myles distance; we turned our course to the south-east, making straight for this land, fired a gun and in the afternoon hoisted the white flag, upon which the officers of the Zeehaan came on board of us, with whom we resolved to touch at the said land as quickly as at all possible, for such reasons as are more amply set forth in this day’s resolution. In the evening we deemed it best and gave orders accordingly to our steersmen to stick to the south-east course while the weather keeps quiet but, should the breeze freshen, to steer due east in order to avoid running on shore, and to preclude accidents as much as in us lies; since we opine that the land should not be touched at from this side on account of the high open sea running there in huge hollow waves and heavy swells, unless there should happen to be safe land-locked bays on this side. At the expiration of four glasses of the first watch we shaped our course due east. Variation 7° 30′ North-East.”

Just before noon they saw land, and immediately turned towards it. They were travelling east, and they turned to the south-east. After noon the council was convened and it was decided to continue south-east and reach the land ‘as soon as possible’.

Tasman’s position at anchor in Marion Bay, Tasmania was -42° 50′s, 147° 57′e (relative to Greenwich). By noon on Dec 13th he estimated his position to be 20° 58′ further East, and he measured his latitude at noon as -42° 10′s.

Correcting his longitude error, based on his actual position at anchor in Tasmania, gives us an adjusted Dec 13th position of -42° 10′s 168° 55′e.

Tasman reported seeing land to the south-east; not south-east by east, or south-east by south… he uses a 32 point compass. When he wrote ‘south-east’, this means that the land he saw lay between south-east by east, and south-east by south… or Bearing 123° to 147°.

Land to the South East

Land to the South East

So what was this land they saw to the south east? … bearing between 123° and 147°, from -42° 10′s 168° 55′e.

The Southern Alps from Gillespies Beach on the West Coast

The Southern Alps from Gillespies Beach on the West Coast

If you look south-east from this location, in the direction 123° to 147° (South-east by South to South-east by East), you see the Southern Alps. Mount Cook would be on the right hand edge of your view, with Mt Tasman slightly to its left.

This picture is taken on Gillespies Beach, on the West Coast. It is 7 ‘myles’ to the peaks. Mt Tasman is on left, and Mt Cook is centre-right.

However, there’s a problem with this.

From his December 13th estimated location, whilst the highest peaks of the Southern Alps are roughly in the direction Tasman gave, they are too far away.

From that location those peaks are 26 ‘myles’ away (194 km), and although it’s obviously difficult to judge ‘line of sight’ distance, this is almost double the 15 ‘myles’ recorded by Tasman. Also, whilst these mountains are high enough to be above the horizon at this distance; at 194 km, they’re a long, long way off. It is sometimes possible to see this distance, from sea level, in New Zealand… but it is quite unusual.

The next morning Abel Tasman saw the land clearly, and made a note in his journal that allows us calculate precisely where he was at noon on Dec 13th… and it’s not where he thought he was.

Abel Tasman had sighted New Zealand but he did not see Mt Cook, or Mt Tasman.

His estimated longitude, even after adjustment relative to his Tasmanian anchorage, was wrong by 116 km.

Lawful property

Abel Tasman banner

Tasman’s expedition was conducted under comprehensive written instructions, and all decisions were taken with reference to these instructions. Tasman didn’t have sole charge of the expedition; he was the president of the ships’ council, on which he held the casting vote.

Their instructions included details on how to proceed when encountering new land, and the method by which they should lay claim to it.

Isaac Gilseman's drawing of the ships at anchor in Frederick Henricx Bay.

Isaac Gilseman’s drawing of the ships at anchor in Frederick Hendricx Bay.

“All continents and islands, which you shall discover, touch at and set foot on, you will take possession of on behalf of Their High Mightinesses the States General of the United-Provinces, the which in uninhabited regions or in such countries as have no sovereign, may be done by erecting a memorial-stone or by planting our Prince-flag in sign of actual occupation, seeing that such lands justly belong to the discoverer and first occupier; but in populated regions or in such as have undoubted lards, the consent of the people or the king will be required before you can enter into possession of them, the which you should try to obtain by friendly persuasion’ and by presenting them with some small tree planted in a little earth, by erecting some stone structure in conjunction with the people, or by setting up the Prince-flag in commemoration of their voluntary assent or submission; all which occurrences you will carefully note in your Journal, mentioning by name such persons as have been present at them, that such record may in future be of service to our republic.”

The bay that they anchored in is now called “Marion Bay” after the Frenchman, Marion du Fresne, who stayed there in March 1772 whilst on his voyage in search of Great Southern Lands.

On the morning of December 3rd, Tasman and Isaac Gilsemans lead another party into Blackmans Bay. They took the same two boats as the day before, and again were a well-armed party with “a number of musketeers, the oarsmen furnished with pikes and side-arms”.

Their caution was based on the accepted wisdom of the day. Tasman’s instructions included the following;

“In landing with small craft extreme caution will everywhere have to be used, seeing that it is well-known that the southern regions are peopled by fierce savages, for which reason you will always have to be well armed and to use every prudent precaution”

They had returned empty handed. They found that the available water in the bay was all so low lying as to be brackish from the tide. On his return he convened the council, and they determined to execute their duty regarding claiming the land, and then move on.

The honour party comprised Tasman and “Pilot-major Francoys Jacobsz, Skipper Gerrit Jansz, Isack Gilsemans, supercargo on board the Zeehaan, subcargo Abraham Coomans, and our master carpenter Pieter Jacobsz.”

They had met with no indigenous people, so only the last of the recommended options was available to them; planting a flag.

“We carried with us a pole with the Company’s mark carved into it, and a Prince-flag to be set up there, that those who shall come after us may become aware that we have been here”

In the course of the afternoon, the conditions began to worsen, and the cock-boat from the Zeehaen, with Gilsemans and Visscher on board, turned back to the ships. Tasman however, pressed on in order to execute their obligation.

Gilseman's drawing of the ships at anchor in Frederick Henricx Bay besides an actual outline, and Tasman's movements in the bay.

Gilseman’s drawing (rotated to north) of the ships at anchor in Frederick Hendricx Bay besides a modern coastline, and Tasman’s movements in the Bay.

“ When we had come close inshore in a small inlet which bore west-south-west of the ships the surf ran so high that we could not get near the shore without running the risk of having our pinnace dashed to pieces. We then ordered the carpenter aforesaid to swim to the shore alone with the pole and the flag, and kept by the wind with our pinnace; we made him plant the said pole with the flag at top into the earth, about the centre of the bay…

…. Our master carpenter, having in the sight of myself, Abel Jansz Tasman, Skipper Gerrit Jansz, and Subcargo Abraham Coomans, performed the work entrusted to him, we pulled with our pinnace as near the shore as we ventured to do; the carpenter aforesaid thereupon swam back to the pinnace through the surf. “

Tasman’s journal for that day recorded that his duty had been performed.

“…we have been here, and have taken possession of the said land as our lawful property”

Conditions deteriorated further. In the evening they had to lower their yards and put out a second anchor, but by the next morning the storm had abated. The storm must have been severe, as on raising the anchors the next day they found that one had both flukes completely snapped off; they raised only the shaft.

Their efforts to find water had been unsuccessful, and so it was decided they should follow the coast “to pass to north to landward of the northernmost islands and seek a better watering-place”. They sailed along the coast noting “several columns of smoke” as they passed.

They had seen no people, but there was little doubt that they had been seen.

When Visscher had explored around Blackmans Bay he’d reported that “they had heard certain human sounds and also sounds nearly resembling the music of a trump or a small gong not far from them though they had seen no one”. While they were exploring, observers on the ships “saw clouds of dense smoke rising up from the land”

Similarly, when the flag was being planted, Tasman observed;

“… leaving the above-mentioned as a memorial for those who shall come after us, and for the natives of this country, who did not show themselves, though we suspect some of them were at no great distance and closely watching our proceedings.”

Tasman’s journal for that day, 4th December 1642, concluded:

“Here it would be meet to describe the trend of the coast and the islands lying off it but we request to be excused for briefness sake and beg leave to refer to the small chart drawn up of it which we have appended.”

Visscher's map of Tasmania side by side with a modern coastline

Visscher’s map of Tasmania side by side with a modern coastline

Visscher’s chart of Tasmania is quite remarkable. It is drawn with west at the top of the page, (shown rotated here) and compares very favourably with a contemporary map, conmsidering that most of the time they were more than 20 km off the shore, and that they had no means of accurately determining longitude.

The next day, December 5th, they tried to follow the coast again, but found themselves unable to.

On the west side of Tasmania they had been concerned about being driven onto the shore, and now, they couldn’t reach it.

Coastal survey of the land they passed on leaving Frederick Henricx Bay.

Coastal survey of the land they passed on leaving Frederick Henricx Bay.

“at this point the land fell off to the north-west so that we could no longer steer near the coast here, seeing that the wind was almost ahead. We therefore convened the council and the second mates, with whom after due deliberation we resolved, and subsequently called out to the officers of the Zeehaen that, pursuant to the resolution of the 11th ultimo we should direct our course due east,…
… we then shaped our course due east for the purpose of making further discoveries”

Now they turned east, having determined to sail at the latitude 41° for a further 26° of longitude.

Sailing east in search of “further discoveries”, another large land extending from 34°s to 47°s, now lay across their path; New Zealand.


Abel Tasman banner

The Council had decided that they should turn east, and in doing so they had avoided potential disaster.

29th October.

“At noon we directed our course to eastward with a north-north-westerly wind and a top-gallant gale; our estimated latitude being 45° 47′, and Longitude 89° 44′; course kept south-south-east sailed 17 miles.”

Tasman's eastward progress

Tasman’s eastward progress

Having just avoided the French Southern and Antarctic lands they ran eastwards for three days, before again turning south-east.

The foul weather and intermittent fog persisted, as did sightings of weed on the water, and at the latitude 49°S Tasman recorded that

“our men begin to suffer badly from the severe cold”.

The weather was so bad that it was impossible to convene the Council. However, they passed messages in a small barrel between the ships.

On Nov 7th, Visscher, the Pilot Major delivered some extraordinary news… the Company’s understanding that the Solomon Islands reached as far as 220°E was certainly incorrect, and could not be relied on. On board the Zeehaen, Visscher had a globe of the world, and a map… and disagreed very significantly on the longitude of the Solomon Islands. On close inspection Visscher discovered that they had different origins for longitude.

The VOC used the convention that zero longitude, the meridian, was measured from the Peak of Tenerife. This was the coordinate system in their map, “the large chart of the South Sea”, the map drawn by Gerritsz showing all the known lands in Australia.

However, the globe was an older device, and had a different meridian.

“The terrestrial globe shows us that the easternmost islands of the Salomonis are in the longitude of fully 220°, reckoning said longitude from the meridian of the islands of Corvo and Floris.”

The globe used the Portuguese convention, having its meridian at the Azores, which at the time the convention was adopted, was the westernmost of any known land.

Even after making adjustments for the different meridians, the discrepancy between the chart and the globe was enormous. Depending on the features compared, the globe and chart differed by between 11° and 19° of longitude.

Their instructions were to sail east, as far as the eastern extremity of the Solomon Islands… but now there was significant confusion about just where that was.

Following a complex series of calculations he decided they should rely on their newer Gerritsz map, rather than the Portuguese globe, and made a written recommendation.

Hence our advice is that we should stick to the 44th degree South Latitude until we shall have passed the 150th degree of Longitude, and then run north as far as the 40th degree South Latitude, remaining there with an easterly course until we shall have reached the 220th degree of Longitude, after which we should take a northerly course so as to avail ourselves of the trade-wind to reach the Salomonis islands and New Guinea…
…Signed, Francoys Jacobsz.

Bad weather continued to make it impossible to convene the Council, and it was not until two days later that Tasman replied to the Pilot’s message.

“Towards evening we dispatched to the officers of the Zeehaan the letter following, together with the Annotations of Pilot-major Francoys Jacobsz, the said papers being enclosed in a wooden canister-shot-case, duly waxed and closely wrapped up in tarred canvas, which case we sent adrift from the stern part of the poop; the letter duly reached its destination and ran as follows:

To the officers of the Zeehaan.

We should have greatly liked to have had your advice on the 7th instant but, time and opportunity being unpropitious, we resolved with the members of our council and our second mates to shape our course north-east as far as 44° South Latitude, and then keep a due east course as far as 150° Longitude; should you agree to this resolution then be pleased to hoist a flag at your stern as a sign of approval that we may duly ratify the resolution. We also request you to do your best to sail in during the night until further orders and, if you should think it possible to come alongside of us in the boat, be pleased to float a flag from the foretop by way of signal, in which case we shall stay for you, seeing that we are very desirous of communicating with you by word of mouth. Farewell. Actum Heemskerk sailing in about 44° South Latitude, this day November 9, 1642.


After reading the above, those of the Zeehaen hoisted the Prince-flag in sign of approbation of our resolution.”

Over the preceding days they had been pushed progressively north, and were now already at 44°S. They accordingly now set their course east.

In the preceding two weeks two decisions had been made that had completely changed the outcome of the expedition.

On the 29th Oct, in heavy fog, they had turned east. Had they continued south they would have met, most likely tragically, with the French Antarctic Lands, which would remain undiscovered until 1772.

From Mauritius, they had sailed 7,000km without sighting land. On 9th November they determined, contrary to their instructions, to run East at the Latitude of 44°S.

That decision placed them in the same latitude as the land that would subsequently bear their commanders name… Tasmania.

On Nov 11th the weather eased and they were finally able to convene the Council.

“We ran up the white flag, upon which the officers of the Zeehaen came on board of us, when we resolved in the plenary Council to run on in the parallel of about 44° South Latitude from our present longitude (averaging 123° 29′) as far as 195° Longitude, being the meridian of the east side of New Guinea as delineated in the chart.”

The Council confirmed that they should sail on in the latitude 44°S.

South Land and progress

The Gerritsz map of the South Seas, overlaid on an image of Australia and Tasman’s progress to 24th Nov.

By 17th November they had reached the eastern extremity of their chart, and passed again into the unknown. Now they were not only further South in this ocean than any Dutchman had ever been, they were also further to the East.

“we estimated that we had already passed the South land known up to the present, or so far as Pieter Nuyts had run to eastward.”

Tasman continued to the East in mixed weather, and the journey was otherwise uneventful except for this unusual event on 22nd November.


Click the image for more about Lodestone

“we found that our compasses were not so steady as they should be, and supposed that possibly there might be mines of loadstone about here, our compasses sometimes varying 8 points from one moment to another, so that there would always seem to be some cause that kept the needle in motion”.

He had sailed over a magnetic anomaly that caused his comapass to vary through a 90° arc. ‘loadstone’ (sic) is a magnetic rock, and in Tasman’s time was used to magnetize to their compass needles.

The following day he compared his position to a location we can verify.

“At noon Latitude observed 42° 50′, Longitude 162° 51′; course kept east, sailed 25 miles; we found the variation to the compass to be 1 degree North-West, so that the decrease is a very abrupt one here; by estimation the west side of New Guinea must be north of us.”

It was 47 days since he left his last known position, Mauritius, and at this point in his journal we can test his ‘dead reckoning’ estimate of Longitude.

On 22nd November he wrote that he believed the western extremity of New Guinea was now due north of his position. The western point of New Guinea lies in 130° 57′, due east of Greenwich. He estimated his longitude that day as 162° 51′, measured East from the Peak of Tenerife. This is 134° 2′ E using our contemporary convention of the Greenwich Meridian.

His longitude estimate error is 3° 5′. In terms of change in longitude from his reference point, Mauritius, this is a 4% error; or expressed the other way, Tasman’s ‘dead reckoning’ of longitude was 96% reliable.

Tasman’s journal for the next day, began innocuously…

“Good weather and a clear sky. At noon Latitude observed 42° 25′, Longitude 163° 31′; course kept east by north, sailed 30 miles; the wind south-westerly and afterwards from the south with a light top-gallant breeze.”

However, that day one of his sailors earned a bonus;

“three pieces-of-eight and a can of arrack to whoever shall first see and observe land”.

On November 24th, 1642 Tasman recorded in his journal. “In the afternoon about 4 o’clock we saw land bearing east by north of us at about 10 miles distance from us”.

coastal survey of Tasmania

The first depiction of Tasmania. Drawn by Isaac Gilsemans from the deck of the Zeehaen. Click to open the source document

The captions on this drawing read:

A view of the coast when you are six miles from it.
A view of Anthonij van Diemens Landt, when you come from the west, and are in 42½° S. Latitude.

Naming detail

An extract from Tasman’s journal where the name Van Diemen’s Landt is conferred. Click to open the source document

“This land being the first land we have met with in the South Sea and not known to any European nation we have conferred on it the name of Anthoony Van Diemens landt in honour of the Honourable Governor-General, our illustrious master, who sent us to make this discovery;”

The land he named in honour of his employer, now bears his own name… Tasmania.


Abel Tasman banner

Abel Tasman finally escaped ‘Old Harbour’ Mauritius on 8th October, 1642. He must have had severe concerns about the strength of his ships, as he spent twice his allotted time there. He was to stop at Mauritius for approximately two weeks gathering provisions; firewood, water and livestock. But he remained there until he was satisfied that his ships were properly prepared for the rigours of the Southern Ocean.

His instructions were to sail from Mauritius South, to latitude 52°S or 54°S, and the instructions were remarkably specific.

As before mentioned, your necessities having been provided for, you will about medio October, or earlier, set sail from the Mauritius, shaping your course with the trade-wind nearly southward, as high as wind and weather shall permit, until about the Southern Latitude of 36 or 38 degrees, when you have got out of the eastern trade-wind, you shall fall in with the variable winds, with which you will always put about on the best tack for getting to the southward, until you get into the western trade-wind, with which you will sail nearly southward until you come upon the unknown South-land, or as far as South Lat. 52 or 54 degr. Inclusive; and if in this latitude you should not discover any land, you will set your course due east

He was to sail south, initially on the ‘Eastern trade wind’, but actually, at the Latitude of Mauritius, the wind is normally from the south-east, as he had so painfully discovered when trying to leave the Old Harbour. The ‘western trade-wind’ he would meet was the Antarctic Circumpolar wind. He would enter this at about 40°S.

In the shifting winds in the transition, he was always to take the tack that would best move them south.

The next day, they were sailing in good weather and a breeze, they still had Mauritius in sight, but after that Tasman began to record deteriorating conditions. Once clear of the influence of Madagascar the ocean swell grew dramatically.

On the 10th October he recorded the sea running ‘high from the south’, and despite all their earlier preparations, the Mizzen Mast broke. They ‘fished’ it. Two days later they had to do it again.

Rigging on the Heemskerck and Zeehaen

Rigging on the Heemskerck and Zeehaen

They pushed on south, but on the 18th October, had to heave to. The Zeehaen had turned to the wind and stopped. They hailed across that the boards that the shrouds were fixed to had worked loosed, and they needed to brace them.

By the 22nd October they were at latitude 38° 11′ and were now deeper into the Southern Ocean than anyone had been before. The most southerly land known was Amsterdam Island; halfway between Good Hope and Australia. The island had first been seen by Spanish explorer Juan Sebastián Elcano in 1522, but was not named. It was re-discovered for Holland in 1633, and named it Nieuw Amsterdam by Anthony van Diemen; Tasman’s boss.

It was on the 24th October that they hit their first big storm. They had reached 40°S; and were now in the ‘Roaring Forties’, the vicious wind that rips around Antarctica.

“…we took in our bonnets, lowered our foresail down to the stem, and ran on before the wind with our mainsail only; we dared not try to the wind because of the strong gale blowing. This gale was attended with hail and rain to such a degree that we feared the ship would not live through it.”

It must have been an extreme storm, as no-where else in his journal does Tasman ever describe concern for the conditions he was sailing in.

In the gale they lost sight of the Zeehaen, and this was a major problem. The Zeehaen was the principal supply ship, but more importantly, she was the only vessel capable of rendering aid should they require it.

They lay to, put a man up the mast,and waited. The next morning, to their great relief, the Zeehaen was sighted. They re-joined, but before they could get underway again, the Zeehaen broke a top yard, and they had to replace it.

Track of Abel Tasman heading into the Southern Ocean

Track of Abel Tasman heading into the Southern Ocean

They were finding the Southern Ocean very tough going.

The following day, 27th October they saw something in the water which gave them significant concern… ‘rock-weed’. There was land or shoals somewhere near.

“Item the 27th.

In the morning before early breakfast we saw a good deal of rock-weed and manna-grass floating about; we therefore hoisted a flag, upon which the officers of the Zeehaan came to board of us; we convened the Council and submitted to their consideration the instructions of the Honourable Governor-General and Councillors of India in case we should see and observe land, shoals, sunken rocks, etc. We then submitted to the council the question whether, now that we observed these signs of land, it would not be best to keep a man at the masthead constantly and make him look out for land, shoals, sunken rocks and other dangers; also what sum had best be fixed upon as a reward to be given to him who should first see land, upon which the Council thought fit to keep a man on the lookout constantly, and to give three pieces-of-eight and a can of arrack to whoever shall first see and observe land …”

The storms were so violent that their ships were breaking under the strain, and when they came, they had no choice but to run with the wind. Control over the direction they sailed was lost and now there was the possibility that when running they could be cast onto rocks.

The following day, matters got worse. They saw pieces of trees and leaves on the water and then, they became fog-bound. They knew that land was close because of the floating debris, but now, they couldn’t see it.

The position was extremely dangerous. They are in un-charted waters; and have no knowledge of the whereabouts of any land whatsoever. They also have no way to stop. They have no brakes. At sea, all the can do is slow their progress; they can either turn up to the wind and slowly drift backwards, or they can put out a sea anchor ( a large canvas bag on a line ) to slow their downwind progress.

There was however something they could do to detect the presence of land, even if they couldn’t see it.

“we time after time fired a musket and now and then also a great gun”.

Concerned that they would strike land that they couldn’t see, they fired guns, and listened for the echo.

On the 29th October, still locked in fog, Tasman convened the council, to ask;

“seeing that in this fog and darkness it is hardly possible to survey known shores, let alone to discover unknown land, it would not be best and most advisable to shape our course to eastward until the advent of clearer weather.”

The Council agreed, and despite not having yet reached the 52°S or 54°S prescribed, they turned East… and that decision probably saved the expedition.

Cook Glacier, Kerguelen Island

Cook Glacier, Kerguelen Island, French Southern and Antarctic lands: Source Wikipedia commons

For the last few days their progress had been south-south-east. This was as close as they could hold to the instruction, to proceed directly south.

Directly in their path, and unseen in the fog, was the 130km wide, French Southern and Antarctic lands; Islands that wouldn’t appear on a chart until 1722.

Under Instructions

Abel Tasman banner

Model of the Heemskerck at the Auckland Maritime museum

Model of the Heemskerck at the Auckland Maritime museum

Model of the Zeehaen at the Auckland Maritime Museum

Model of the Zeehaen at the Auckland Maritime Museum

In order to appreciate the progress of Tasman’s 14642 voyage it is necessary to understand the circumstances under which he was operating.

The VOC company wanted to find the Great South Land, to see if they was anything there that they could exploit commercially. They also wanted to know if there was a passage between the Indian Ocean and the Pacific Ocean through which they could gain access to the gold bearing coast of South America.

These were the two goals of the expedition.

Tasman was provided with two ships for the expedition, the Heemskerck, and the Zeehaen. Both ships carried cannons. He had 110 men in total, 19 of them soldiers, full rations for a year, and rice sufficient for 18 months.

The cost of the expedition was enormous. Not only did the VOC provide the vessels, crew, provisions, and goods for barter, they also diverted these vessels from profit making activity.

They did not take on this expense casually.

Tasman was given comprehensive written instruction on where he should go, and what he should do on discovering land. The VOC also put in place a management structure to ensure that their instructions were followed.

In the course of their business, the vessels of the VOC carried cargoes of incredible value… and this was the caused of significant temptation among skippers and crews; the risk of having a whole cargo stolen was high. For this reason, the ships’ skippers did not have sole charge of their vessels, rather, each ship’s operation was governed by a ‘Ship’s Council’.

All VOC vessels sailed with ‘Supercargo’ , a Company man, in charge of all trading activity. The Supercargo was always a council member.

It was the duty of the Ship’s Council to ensure that the instructions of the company were carried out.

On Tasmans expedition, the Council comprised:
From the Heemskerck: The Commander, Abel Jansz Tasman, The Skipper Yde T’jercxsz, The Pilot-Major Francois Jacobsz (a.k.a. Visscher) and Subcargo Abraham Coomans, who also acted as Secretary.
From the Zeehaen:The Skipper Gerrit Jansz, The Supercargo Isaack Gilsemans, and the first steersman Henrick.

The Commander, Abel Tasman, was an equal Council member except that in the case of a tied resolution, he had a casting vote.

“In this Council all matters relating to the progress of this voyage and the execution of our instructions will have to be discussed and determined, the Commander to have a double vote in case of equality of votes; “

Tasman was the president of a management committee, whose duty it was to execute the written instructions of the company, and Abel Tasman could not vary from those instructions without the approval of the Council.

In this respect, the voyage of Abel Tasman was completely unlike all the other famous expeditions. Tasman was not able to make decisions quickly, nor could he win through with an extreme proposal; exploration by committee was a cautious, even timid, process.

He had an additional difficulty in that his Council was distributed across the two vessels. In order to make a decision that was at variance with their instructions, Tasman had to convene the Council. This was done by flying a large white flag, upon which the Council members on the Zeehaen would come across. But to do this required that the vessels drop their sails, and lay to, and could only happen when the conditions permitted passage between the vessels.

The Gerritsz map of Australia carried by Abel Tasman

The Gerritsz map of Australia carried by Abel Tasman

A depiction of their arrival in Tonga, drawn by Isaac Gilsemans

A depiction of their arrival in Tonga, drawn by Isaac Gilsemans

Two of the Council members warrant particular mention.

‘Francois Jacobsz’ also known as ‘Visscher’ was the Chief Pilot and navigator. He was the chart-maker, and it was his calculations that were used to calculate their current position.

‘Isaack Gilsemans’ had a dual capacity. He was the company’s trader, but he was also the draughtsman, responsible for drawing the coastal surveys and other illustrations in the Commanders journal.

Gilsemans had a bewildering array of goods on board to barter with. Among them were; Tin, Pewter, Lead and Steel, with a small quantity of gold and pearls. Iron goods included, pots and pans, and knives and hatchets. His hoard also included some curiosities; hundreds of mirrors and combs and intriguingly… elephants teeth, and a brass bath.

The Ship’s Council was guided by comprehensive written instructions. In addition to the course they should sail they were given instruction on the men’s weekly rations, aimed at conserving their provisions. They were explicitly warned to take care of their stocks of water and firewood.

They were instructed to keep a lookout when approaching land, and advance a reward to the man first sighting it. They were also given clear instruction on how they should lay claim to any land found, and to inquire (without showing too much interest) about whether or not there was gold thereabouts.

On finding land they should follow its coast to see where it lead, taking care to note all; “islands, points, turnings, inlets, bays, rivers, shoals, banks, sands, reefs, cliff; rocks, etc”. Each of these they must “carefully map out and describe, and also have proper drawings made of their appearance and shape”.

In addition to the written instructions, Tasman was provided with, among other items; the Gerritsz map of Australia, notes from the skipper of the Gulden Zepppart, a Spanish description of the Solomon Islands, and a lexicon of words of the Solomon Islanders.

In his quest for the South Land, the route that Tasman should navigate was this:

The course instructions given to Abel Tasman

The course instructions given to Abel Tasman

From Mauritius they should sail south to the latitude of 52°S or 54°S. Then they should turn east, until reaching the longitude of the eastern extremity of the Solomon Islands (incorrectly thought to be 220° East of the Peak of Tenerife) before turning north. Then they should proceed at fist northwards, and then North-west to New Guinea, and the Philippine’s, before finding their way back to Batavia.

If Abel Tasman had followed the directions he was given, then he would have discovered nothing at all.


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Tasman’s route to Mauritius

Abel Tasman sailed into the old ‘Grand Harbour’ on the South-East coast of Mauritius on 5th September 1642. There, at the VOC fortress of ‘Fredrick Hendrik’ he met with it’s commander Adriaan van der Stel.

Mauritius was a new colony, having only been established in 1638. It was named after the Dutch Prince Mauritius and lay between the Dutch colonies at Batavia and Cape Town. It was a strategically positioned haven for the many VOC ships on that route, and had an abundant supply of a highly prized commodity; Ebony. As well as keeping the colony a secure refuge for VOC vessels, Adriaan van der Stel was tasked with harvesting ebony for shipment to the European markets. Supply ships arrived at the outpost bringing provisions, munitions and slaves to work in the forests. They and laden with valuable ebony.

Prior to the Dutch, Mauritius had been visited by the Portuguese from 1507 onwards, but before that it was already known to Arab traders, and had first appeared on a Portuguese map of the world in 1502.

Cantino map 1502

The Cantino Planisphere, 1502

Abel Tasman was in Mauritius to refresh his men and take on board final provisions before beginning the exploration part of his voyage. The instructions he was given were clear about what he should do once he arrived.

“… you will take your way westward to the island of Mauritius (running in sight of Diego Rodrigos), and come to anchor there in the South-east harbour before the fortress of Fredrick Henrick, where you will hand to Commander Adriaan Van der Stel our annexed letters together with the commodities you have taken on board for the said island; while you are there, you will quickly and properly provide your ships with water, firewood and refreshments, bestowing on this no more than 14 or 15 days, however, or till. the 12 or 15th of October at the latest, taking due care that during that time your crews be properly refreshed and dieted exclusively on fresh viands, to which end we have given the needful orders to Commander Van der Stel, to assist you to the extent of his power, and if necessary to allow you to go a-hunting for wild animals.”

Tasman’s instructions made it plain that he should re-provision and refresh his men, taking no longer than 14 or 15 days to do so, but he took twice that time.

When Tasman left Batavia the first thing he did was go back to anchor; “where we refitted our ship which was disabled to such a degree that we could not possibly have put to sea in her”.

After crossing the Indian Ocean he was even more concerned about the condition of his vessels, and spent a month refitting them before sailing again.

These diary extracts show the extent of the re-fit he undertook on the Heemskerck.

“We were engaged nearly all day repairing our ropes and tackle; considering that our rigging was old, weak and not much to be depended on we added three more large ropes to the rigging on both sides the main and foremast in order to steady the same”

“In the morning our skipper, together with the carpenter aforesaid, went to the wood in the boat for the purpose of fetching thence the timber, and took the same to the fortress of Frederik Heyndrick, there to be sawn into boards of the most fitting dimensions.”

“In the morning we sent ashore our chief boatswain and boatswain’s mate with a number of sailors and a quantity of cordage in order to make ropes.”

“We sent a bag of rice to our men in the wood and fished our main-yard.”

“We fished our foremast at the back”

“In the morning ourselves and Gerrit Jansz, Skipper in the Zeehaan, together with a number of sailors with axes, went ashore to the wood in order to procure fitting timber for top-yards, anchor-stocks and mizzen-yards etc., for the purposes of our further voyage; we returned towards evening bringing a piece of round timber proper for fishing a top-yard, and also an anchor-stock for ourselves and two ditto for the Zeehaan. “

“This day we had a number of sawn boards brought from shore and a quantity of rope made ashore.”

“We fetched from the wood 3 anchor-stocks and a round piece of timber for a top-yard”

“The carpenters caulked the ship on the outside, stopped all the leaks they could find, and furthermore overhauled everything and duly pitched the seams.”


The Heemskerck and Zeehaen anchored in front of Fort Frederick Henrick with the supply vessel, Arent

While many of his men were occupied with the repairs, the others worked on re-stocking provisions. Boatloads of firewood and water were rowed out to the ships, and fresh meat was brought in.

In the month that they were anchored off the fortress they hunted, and brought back to the ships; 73 goats, 18 hogs and 26 cattle.

They had previously determined that they would get under way again on 4th October, but when that day came, they found they were unable to leave.

October 4th.

“This was the day we had fixed upon for putting to sea but owing to contrary winds we were unable to stand out to sea…”

They remained stuck in the harbour for the following three days;

“The contrary wind still continuing, we were unable to beat out of the bay, “

“We warped the kedge-anchor to get out at the south-east entrance and kedged a second time, but were compelled to give it up owing to the strong contrary wind.”

“The wind blowing from the east we were still busy with the kedge-anchor; in the evening we came to anchor under the islands in front of the bay in sixty fathom muddy bottom“

departing mauritius

The ‘Old Harbour’, Mauritius

Exasperated, Tasman wrote this in his journal;

“This bay is very hard to get out of seeing that the south-east wind is continually blowing here; whoever has no urgent business here had better keep out of it.”

Tasman’s difficulty was not unusual. The Heemskerck was a square rigged vessel that could only sail either downwind, or across the wind. It could not advance significantly upwind. If the wind came from the direction he wished to go then Tasman could not make direct progress, he had to tack. The harbour entrance he had to pass through was narrow and turning, and there wasn’t enough space to tack to make upwind progress. For Tasman it was either wait, or ‘warp’.

Heemskerck's pinnace

A model of the Heemskerck’s pinnace at the Auckland Maritime museum. Inside the boat is a small kedge anchor

‘Warping’ was the technique they used to move the vessel if the wind opposed them, or if there was no wind. The rowboat was sent out from the ship with a small anchor in it, a ‘kedge’ anchor. This anchor had a rope trailing back to the ship. The rowboat positioned itself ahead of the ship, and lowered the kedge anchor on a light line. On the ship, the main anchor was lifted and rope to the kedge anchor was hauled, pulling the ship forward. Then the ship’s anchor was lowered again, and the rowboat used the recovery line to lifted the kedge anchor, and moved forward. The process was repeated, and the ship moved forward in slow, small increments.

It was a laborious way of making ground, but was often the only means of getting out of a difficult, or becalmed harbour.

On October 8th, the wind turned and they finally managed to get themselves into open water.

“In the morning the weather rainy with a light land-breeze and whirlwinds; we weighed our anchors but had to drop them again owing to contrary winds; about 8 o’clock the wind turned to the north-east by east, we weighed anchor and accordingly ran out to sea south-eastward, for which God be praised and thanked; the southern extremity of this island of Mauritius is in 20° 12’”

Clear of the harbour and it’s enclosing reefs they turned right, and headed out into the unknown South.

Tasman’s navigation: Part 2

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latitude and  longitude

Latitude and longitude on a globe.

Longitude was the big issue for Tasman. He simply had no way of measuring how far east or west he was. There wouldn’t be a method to readily resolve longitude until Cook carried the experimental Harrison ‘K1’ instrument on his second Pacific voyage in 1772. The Harrison ‘K1’ was a clock.

The successful resolution of longitude hinges on being able to know time very accurately.

The Italian explorer Amerigo Vespucci made an insightful observation during a voyage to the America’s.

“…one night, the twenty-third of August 1499, there was a conjunction of the moon with Mars, which according to the almanac was to occur at midnight or a half hour before. I found that…at midnight Mars’s position was three and a half degrees to the east.”

Vespucci was watching a transit of the moon by mars, but it didn’t happen at the time he expected.

The earth makes a complete turn on its axis every 24 hours, and in this time the sun makes a complete revolution of the earth (to the terrestrial observer). It rises in the east, sets in the west, and then becomes invisible below the horizon until it appears again in the east. ‘Noon’ is when the sun reaches the highest point in the sky at a given location… noon is not simultaneous at all places on Earth.

The Prime Meridian at Greenwich

Standing with one foot in the east, and one in the west, at the Royal Observatory, Greenwich

Harrison K1 'one day' watch

The Harrison ‘K1’ watch carried by James Cook on his second Pacific voyage.

To a terrestrial observer, ‘noon’, when the sun is at its highest, occurs every 24 hours… precisely.

The sun moves through the sky, east to west, at 15° per hour. If I travel west then ‘noon’ occurs later, if I travel east it occurs earlier. The time that noon occurs is directly related to the distance I travel east or west.

‘Noon’, at a location 15° to the west of me, will occur exactly an hour later than at my location.

If you had an accurate clock, and set it to 12:00 ‘midday’, exactly noon at your point of departure, then you could work out your longitude anywhere in the world.

When you observe noon at your current location, and compare this to the time on the clock, then the time difference tells you your current longitude. If noon locally occurs 1 hour before noon at your departure point (which is shown by the time on your clock) then you are 15° to the east of it.

1 hour time difference between local noon time and origin noon time = 15° difference in longitude. If you know the local time at any place on the earth, then you can calculate your longitude based on the difference between local time and the time at your origin.

By the time Cook first sailed the pacific in 1769 an astronomical method had been developed for reckoning the time at Greenwich based on observations of the moon and stars. It was important to know the time at Greenwich as this was the location the British chose as the line of 0° longitude for their charts. Known as the ‘Lunar Distance’ method it involved measuring the angular distance between a star and the moon, the star’s elevation above the horizon, and the moon’s elevation above the horizon. The technique was quite accurate, but difficult. It took about four hours to perform the necessary calculations, but it yielded the time at Greenwich when the observations were made.

The difference between ‘local time’ and ‘Greenwich time’ allowed Cook to calculate his longitude, but incredibly, Cook’s ‘local time’ was still based on hour-glasses, corrected daily by his observations of the sun. On his first voyage Cook had no clock of any description.

Regardless of how tedious the process was, the ‘Lunar distance’ method produced the required result.

These days we still use Greenwich as the zero point for longitude and as the ‘normal’ point for time zones, but this convention was not universally adopted until 1884.

James Cook, using the ‘Lunar distance’ method, was able to calculate his longitude with such confidence that he no longer sailed ‘lines of latitude’… he could set a course that took him directly to his objective.

When Cook set out on his second Pacific voyage in 1772 he carried the experiment ‘K1’ watch. It was such an accurate timekeeper that he later wrote to the Admiralty… “Mr Kendall’s watch has exceeded the

expectations of its most zealous advocate…”. With this reliable timepiece Cook could determine his longitude both reliably and quickly. All he had to do was find the local noon time, by observing the sun’s height, and then read from the K1 clock how far advanced, or retarded this was from 12:00. One minute of difference in these times represented a quarter of a degree of longitude distance from Greenwich.

By 1772 the longitude problem was solved, but when Abel Tasman was sailing 140 years earlier, and he had to make do with far less reliable techniques.


Tasman had no instrument from which to directly calculate his longitude, yet in his daily journal he recorded both his latitude and his longitude… so how was this done?

What he did was estimate how far he thought he had traveled since the previous day, and in what direction. He measured his latitude at noon every day, and recorded that, and then he used his estimate of distance and direction traveled and added this variation in longitude to his previous days entry.

His estimate of longitude was cumulative, based on daily estimates of speed and direction since his departure from a known location. Thus, any deficiency in his estimate was compounded. Over the course of his 5,500 km journey across the Indian Ocean, his estimate of longitude was in error by 670 km.

He made his estimate based on two things; his speed, and the direction he was travelling. If he knew his speed, and the direction he had traveled, then he could calculate from that how far east or west he had moved since the previous day.

Measuring a vessels speed

The equipment used to measure a vessels speed

Leeway diagram

‘Leeway’ is the downwind drift of the course caused by the pressure of the wind.

Duyfken hourglass

An hourglass on the replica of the Duyfken

This technique for estimating your position without direct measurements is called ‘dead reckoning’. However, these estimates of both speed, and direction had their difficulties.

He measured his speed with a spool of thin rope, knotted at set intervals and a floating baffle. It took three sailors to measure the speed. One held the rope spool, the second dropped the float into the water, the third turned a 30 second sand glass. The second person started counting knots as they passed through his hand, and at the end of the 30 seconds the count was recorded. The number of knots that had passed was the speed of the vessel.

The direction a sailing ship travels is not the same as the course it is sailing.

The issue here is ‘leeway’; that is, the sideways drift of a ship to leeward (downwind) of the steered course. If a ship is going sideways across the wind, then as the sails propel them forward, the pressure on

the sails pushes the ship sideways across the water in the downwind direction. Their ‘course’ is the direction they’re pointing, their ‘course made’ is the direction actually traveled. The difference is their leeway.

A ship with a deep and broad keel will have a smaller sideways slippage, or leeway, than a ship with a small narrow keel.

An experienced skipper will have a good understanding of his vessel’s leeway at any sailing angle, but this is only a ‘best guess’. A more reliable way to determine ‘course made’ is to look at the wake left by the vessel, and take its bearing from the ships compass.

Tasman’s estimate of how far he had traveled each day was most determined by how accurately his measurements represented the days sailing. On any given day they would change course several times, and for each of

these tacks; speed, direction and duration were noted. ‘Duration’ was determined from the 30 minute sand glasses used to set the sailors’ watches. The sequence of course changes was plotted on a chart to determine the gross determination of course and distance for the day.

Tasman measured from this how his longitude had changed since the previous day and added thius to the previous days longitude. This is what he recorded in his log.

Every step of this process included potential error, and these errors compounded. However, even if his estimate of course and direction had been perfect, this method of ‘dead reckoning’ still contained an inherent error. The difficulty is, that the speed and direction measured is not the actual speed and actual direction… it is the speed and direction relative to the body water they are sailing on.

The observations Tasman made took no account of any movement in the ocean, and the ocean is not generally stationary, it moves in currents. If Tasman was sailing into a current then he would overestimate their actual speed, if they sailed with the current he would underestimated it. Tasman was completely oblivious to any current in the ocean body, so his estimate of longitude took no account of this movement. Tasman’s journey from the from Batavia to the Mauritius took him along the South Equatorial Current… a current flowing to the west. This is why he encountered his destination two days earlier than he expected.

Tasman's chart side by side with a 

modern map

Tasman’s chart side by side with a modern map

Tasman’s longitude estimate is only to be relied on over short time periods; otherwise, as his daily errors compound, the position indicated becomes increasingly less representative.

Given Tasman’s lack of knowledge regarding his true position, it is remarkable that his chart is even recognisable as New Zealand. Yet, despite not knowing his longitude, it bears astonishing similarity to a modern map.

Tasman’s navigation: Part 1

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Gerritsz world map

Gerritsz world map, 1616 (click to enlarge)

Abel Tasman was travelling at a time when the Earth was properly understood to be a globe, and there was a standard method used to represent any position on the globe.

latitude and longitude

Lines of latitude and longitude

‘Longitude’, or how far east or west around the globe you were, was measured in degrees around a circle located on the equator. Lines of equal longitude continued directly north-south, to the poles. At the time Abel Tasman was voyaging, the Dutch convention was that all longitude was measured as East or West of the Peak of Tenerife. The Greenwich ‘meridian’, the line of 0° Longitude, wouldn’t be universally adopted until 1884.

Similarly, how far north or south you were, ‘Latitude’, was measured in degrees north or south of the equator, relative to the centre of the Earth.

This measurement system allowed any position on the globe to be represented unambiguously by the pair of numbers describing its latitude and longitude.

However, being able to accurately represent a location on the globe is quite different to working out the latitude and longitude of your current position… and Abel Tasman had only rudimentary methods for deriving this.

Tasman’s journal records his latitude and longitude, as well as his course directions, and bearings to visible features. In order to successfully interpret Tasman’s journal and charts it is important to understand just what he is measuring and recording.


Tasman reports course directions, and directions to land features using a 32 point compass. Most people are familiar with 16 point compass notation, but Tasman’s compass has a subdivision between each of those divisions with the additional direction indication ‘by’. The pattern of the compass used by Tasman is shown below.

lat and lon

Abel Tasman’s compass

His compass was a large and crude looking instrument suspended in a shape rather like a hanging flower basket. Inside that housing, the ‘card’ carrying the magnetic needle, was balanced on a needle. The top was sealed over with glass to keep it watertight.

Mounted around the top was a cross bar with sights on each end. These sights were used for lining up land features and also for getting accurate bearings of the sunrise and sunset positions.

All readings from a compass contain a discrepancy known as ‘variation’ which must be corrected. The ‘north seeking pole’ of the compass does not actually point quite to the true north.

The Earth’s magnetism is caused by the spinning ball of molten iron in the Earth’s core. The axis of that magnetic field is not perfectly in line with the axis that the Earth rotates around. The angular difference between the ‘true north’ position, and ‘magnetic north’ is called the ‘variation’. To compound matters, variation differs as you move around the globe, and different rock conditions cause local changes in the variation angle, as Tasman noted on Nov 22nd 1642;

‘we found that our compasses were not so steady as they should be, and supposed that possibly there might be mines of loadstone about here, our compasses sometimes varying 8 points from one moment to another’

To determine precisely where ‘true north’ was in comparison to his compass, Tasman used the sun. He measured the bearing of the rising sun, and that of the setting sun. True north lies directly between these positions (in the Southern hemisphere the sun still rises in the east and sets in the west, but it progresses there via the north). His variation on that day was the difference between what his sunrise/sunset bearings reported as north, and what his compass showed.

Tasman’s journal records all bearings as ‘true’ not ‘magnetic’; he had already made the correction for variation as he wrote his journal. On days that he was able to see the sunrise and sunset he also recorded the variation.


How far north or south you are can be worked out from the knowing maximum height of the midday sun.

At the equator the midday sun is overhead, but at the poles it is only on the horizon. The further you move from the equator, the lower the angle of the midday sun. The angle it deviates from straight overhead is the angle you are away from the equator.

This is almost the correct answer, but like variation there’s another little twist. The Earth’s axis of spin isn’t quite upright in relation to its orbit around the sun. This is what causes summer and winter, and at any location on the globe, the midday sun is higher in summer than it is in winter.

There is a special correction chart for this, and Tasman carried one. It is a table showing the height angle, or ‘inclination’ of the midday sun at the equator for each day of the year. By comparing your measured midday inclination to the inclination at the equator for that day, you can derive your latitude.

As long as Tasman knew what day it was, and could measure the inclination of the midday sun, then he could work out his latitude.

Cross staff

Cross staff

In the fourteenth century Astronomers developed an instrument that did exactly this, and it quickly became an essential mariner’s tool. It was called a ‘cross staff’ among other names, and was a simple but remarkably effective device.

The cross staff had a long straight shaft, with another sliding bar mounted perpendicular to it in a way that allowed it to move up and down, like a trombone.

To use it you rested the end of the shaft on your cheek under your eye. You the slid the crossbar up and down, and raised the long bar until one tip of the crossbar was on the horizon, and the other tip on the sun.

The long bar of the cross staff was graduated with measurement marks. The position of the crossbar along the long shaft indicated the height of the sun in degrees above the horizon. Starting just before noon you measured the height of the sun, and kept measuring the inclination until it passed its peak. The highest angle recorded was the noon inclination.

It was a crude device, but it worked surprisingly well. Christopher Columbus used one of these to cross the Atlantic and return to the same Island in the Caribbean three times.

Tasman however, probably did not use one of these.

The cross staff was simple but using it had two major difficulties. You had to look at two places simultaneously; the horizon and the sun, and any movement of the long shaft as you did this introduced an error. The other issue was a practical one… you had to look directly at the sun.

Tasman’s journal records latitude to the minute. You can’t reliably make a measurement to the nearest minute of a degree with a cross staff, it’s simply too crude.


Hoekboog, or back-staff

Willem Jansz Blaeu was a famous map maker. He prepared maps for the VOC as a contractor and was a close friend of Hessel Gerritsz. In 1625 he published this illustration of a ‘Hoekboog’, or ‘angle bow’. This was a more accurate instrument that overcame the issues of the cross staff. It had been in use by the Dutch since at least 1623.

With the Hoekboog you stood looking at the horizon with your back to the sun (hence the English name for this type of instrument, the ‘back-staff’).

The eyepiece ‘F’ slides up and down, on a graduated bar ‘D’. You look through the eyepiece at the flat plate ‘A’. This has a notch cut in it, which you look through and line up with the horizon. The piece ‘G’ has a sharp edge on it and casts a shadow from the sun behind onto plate ‘A’. By adjusting the eyepiece up and down the suns shadow is made to line up with the horizon. Then the ‘inclination’ angle is read off the graduated bar ‘D’.

In his journal Tasman recorded his daily latitude and this was remarkably accurate. The latitude he recorded for Cape Foulwind is only wrong by 8km. From his deck, an observer could see a 100m high cliff from 40km away.

The cross staff and the Hoekboog were both accurate enough to have the error in measured latitude smaller than the distance that you could see. They were accurate to get you within sight of your objective.

There was no similar instrument for measuring Longitude. Whilst mariners could reliably know how far north or south they were, they could not confidently asses their position east-west.

It was because of this that the common practice for travelling long distances across the open ocean (where there are no physical features to tell you where you are) was to sail ‘lines of latitude’.

On a long journey on the featureless ocean, mariners would manoeuvre themselves to the same latitude as their destination, and then hold their course on that latitude until their objective came into sight. Tasman’s journal shows that this is precisely what he did on his journey to the Mauritius.

Aug 17th.

‘it was resolved that from Sunda Strait we shall sail 200 miles to the south-west by west, as far as 14° South Latitude; from there to the west-south-west as far as 20° South Latitude, and from there due west as far as the island of Mauritius.’

Mauritius lies in the latitude 20°S, and Tasman could measure his latitude accurately enough to be within sight of features at a given latitude. So he moved to the latitude of the Mauritius, and continued on until his destination came into view.

He was able to confirm that he had reached his destination by consulting his collection of coastal surveyings. These were drawings showing what the coast looked like at specific places. If you were trying to find a given place, and were in the correct latitude, then when you saw land you compared it to what you saw in the drawing. If it was the same, then you had arrived.

On Tasman’s voyage they were expected to meet new lands, and in order to enable other mariners to find these places in the future they drew outlines of the coasts that they saw.

All VOC vessels had a ‘Merchant’ on board; the person in charge of buying goods to trade. On Tasman’s voyage, the Merchant was carefully chosen for his additional skills. They appointed… ‘Jsaack Gilsemans, who is sufficiently versed in navigation and the drawing-up of land-surveyings’.

The illustrations in Abel Tasman’s journal were drawn by Isaac Gilsemans, from the deck of the Zeehaen… and these illustrations included coastal surveyings.

When they discovered new land in the Southern Ocean they named it ‘Anytony van Diemens Landt’ after the Governor of Batavia. Gilsemans recorded the outline of this land so that subsequent mariners could correctly identify the location.

When you have reached the West Coast of Tasmania, at the Latitude of 42° 30′ you will see this.

Tasmania coastal survey

Tasmanian coastal drawing by Isaac Gilsemans

The captions read:
A view of the coast when you are 5 myles from it.
A view of the coast when you are 2 myles from it.
A view of Anthonij van Diemens Landt, when you come from the west, and are in 42½ S. Latitude.

Without knowledge of longitude, coastal surveys were an essential part of navigation. When a mariner had located land at the specified latitude he could verify his position by comparing what he could see, with the coastal survey. If he saw the same in the drawing that he saw from the deck, then he knew precisely where he was… and he could then correct his longitude accordingly.

As Abel Tasman approached Mauritius his reported longitude was in error by 670 km, but it was nearly correct when he left. The Dutch navigators used the coastal surveyings to re-set their longitude.

Tasman had no instrument for measuring longitude, yet for his noon position he reported both latitude AND longitude. So how was this done?

Across the Indian Ocean


After mounting disagreement with Parliament, Charles I raised his standard at Nottingham castle, beginning the English Civil war. In a few years’ time the Black Death would kill half of London’s population of 460,000. The following year a huge fire swept the city of the Plague, but 80,000 of the surviving population lost their homes to the flames.

In the America’s, the Dutch were forced to abandon their garrison on Staten Island (New York) for the safety of Fort Amsterdam after fierce attacks from the natives.

Isaac Newton was born, Galileo died and William Shakespeare had been dead for 26 years. Rembrandt was at the peak of his career.

The world had not yet seen a thermometer, screwdriver or piano.

 On August the 14th 1642, two ships, the Heemskerck and the Zeehaen, well manned, well equipped and well provisioned, slipped their moorings in Batavia. The ships were setting off in search of the ‘Great South Land’ believed to exist somewhere in the Southern oceans. Abel Janszoon Tasman had command of this voyage of discovery for the VOC (Dutch East India Company).

Abel Tasman banner

‘Batavia’ was the name of the VOC’s trading fortress in Java, Indonesia. Today, we know it as Jakarta. They were sailing out into the un-charted and the unknown, and they were already far, far away from home. The ships and crews were Dutch, and their home port was Amsterdam, half the world away.

On the evening of August 13th, Abel Tasman visited Antony van Diemen, Govenor of Batavia, and received his final written instructions. These instructions included the line;

‘You shall then, in the morning, early, after completion of mustering. go under sail together, and endeavour to come out of Selat Sunda as quickly as possible, setting course in order to get soon into the southeast trade wind, with which you shall take your way westward to the island of Mauritius’.

The start of Tasman's journal

The first page of Abel Tasman’s journal

Tasman duly set sail first thing in the morning, heading to Mauritius. At the end of that Day, Abel Tasman sat down in his cabin on the Heemskerck, and wrote the first entry in his journal.

‘This day August 14, A.D. 1642, we set sail from the roads of Batavia with two ships, the Yacht Heemskerk and the Flute Zeehaan, the wind being north-east with good weather. On the same day in the evening the Zeehaan ran aground near the island of Rotterdam, but got afloat again in the night without any notable damage, after which we continued our voyage to the Straits of Sunda.’

Abel Tasman and his two ships had barely got under way before they had a near disaster. The Zeehaen, fully laden with supplies for 110 men, ran aground before leaving the harbour. We don’t know the precise details of the incident, but it’s very likely that the crews were, to put it plainly, ‘under the weather’, and not performing at their best. By the evening he was still in the harbour, and even the next day he was only 10km from the wharf when he lowered the anchors again at ‘Anjer’ Island ( now known as Pulau Anyer ).

Ocean voyaging was a dangerous business, and many did not survive it. For the common sailors, the days preceding voyages were usually spent in the port’s brothels and grog houses. On departure one of the skipper’s first tasks was to gain a sober crew. It was common practice to leave port, and then immediately anchor up again until the effects of the gin wore off. Back at anchor Tasman set about making the two ships, and their crews, fit to venture out into the Indian Ocean.

August 15th.

‘Towards evening we went to Mr. Sweers, who was on board the Yacht Bredam, from whom we understand that at Bantam point there lay at anchor a quelpaert, newly arrived from the Netherlands; at night we anchored off Anjer in 22 fathom, where we refitted our ship which was disabled to such a degree that we could not possibly have put to sea in her.

That evening he visited Salomon Sweers, newly returned from Head Office in Amsterdam. Sweers was a big wheel in the VOC machine. At the time, the VOC was the most successful business on the planet, and Batavia was the Far East hub of that profit. The Batavia operation was run by the ‘Council of the Indies’. Salomon Sweers was both the VOC’s chief accountant in Batavia, and a member of the ‘Council of the Indies’. Sweers not only wielded a lot of clout, but he was no doubt carrying final messages from Head Office regarding Tasman’s expedition. On his return, Tasman would have to account to Sweers for all expense incurred.

Sweers returned to Holland in 1646. In his time in Batavia he accumulated a large collection of papers and artifacts, and these eventually found their way to the Netherlands State Archives. Among these documents was a copy of Abel Tasman’s Journal… the journal that is quoted here.

Tasman remained at anchor, getting everything ‘ship shape’ (crew included), before finally getting underway on the evening of the 16th. He sailed through the Strait of Sunda, out into the India Ocean, and west toward Krakatoa. 241 years later, Krakatoa would cease to be a notable landmark.

August 16th.

‘The wind continuing east with a steady breeze, the current running fast from Sunda Strait; at night we weighed anchor with the wind blowing from the land, set sail and shaped our course so as to pass between the Prince Islands and Cracatouw.’

Leaving Batavia

Leaving Batavia

August 17th.

‘In the morning we had the Prince Islands south-west and Cracatouw north-west by north of us, the wind being south-east, our course south-west by west; at noon we had the southernmost of the Prince Islands east-south-east of us at 5 miles distance, ourselves being in 6° 20′ Southern Latitude and 124° Longitude; in the afternoon we drifted in a calm; in the said afternoon it was resolved that from Sunda Strait we shall sail 200 miles to the south-west by west, as far as 14° South Latitude; from there to the west-south-west as far as 20° South Latitude, and from there due west as far as the island of Mauritius.’

They were underway.

From Krakatoa it was an uneventful journey to Mauritius. They sailed West-South-West until they reached the latitude of 20°S, and then sailed West until they met land. Abel Tasman had fast ships. He completed the 5,500 km crossing of the Indian Ocean at an average of 250 km per day.

September 5th.

‘In the morning we saw that it was the island of Mauritius; we steered for it and came to anchor before it at about 9 o’clock, we being then in Latitude 20°, Longitude 83° 48′. When we saw the island of Mauritius we were by estimation still 50 myles east of it.’

Tasman thought they were still about two days from Mauritius when they sighted land, but in the morning light they recognised the island. He recorded in his journal ‘we were by estimation still 50 myles east of it’ (One Dutch Myle is 7.4km).

Leaving Batavia

Arriving in Mauritius

If we take the longitudes recorded in his log, we see that when Tasman sighted Mauritius he thought he was 41° 51’ west of his departure point. Whereas he was actually 48° 17’ west of Batavia. While he recorded that he was ’50 myles’ short in his estimate, he understated it very significantly indeed. He was actually 91 ‘myles’ awry… that’s 670 km.

There is a huge discrepancy between where he thought he was, and where he actually was.

This highlights the major issue confronting navigators of the day… they had no reliable means of determining their longitude.

Abel Tasman didn’t actually know where he was.

The Great Southern Land

Abel Tasman banner

The VOC was constantly striving to improve their business. They found ways to be more cost efficient by carrying back loads into Japan and the Malay Peninsula, and were regularly improving the routes they took, to shorten the journey times. They also periodically invested directly in new exploration.

Searching for new goods to trade was a very expensive business; it bore a double cost. There was the cost of provisioning a vessel and paying its crew, but there was also the ‘opportunity cost’; while a vessel was off exploring, it wasn’t performing the profit generating task of carrying goods back to Europe. This made exploration a difficult business activity to justify. However, the “Heeren 17”, the 17 man council that ran the VOC decided in 1605 to assigned two small vessels specifically to the task of exploration; the Deft, and the Duyfken. The VOC took this expensive task extremely seriously, as is demonstrated by their choice of skipper. Willem Janszoon, who commanded the Duyfken, was also a member of ‘the Council of the Indies’; the management team responsible for the VOC’s operations in Batavia.

In 1606, Willem Janszoon commanding the Duyfken, was exploring the off Southern coast of New Guinea. He took a course, south through the Arafura Sea, then south-east. There he met new land, and though he assumed this to still be a part of the New Guinea coast, he had actually discovered Australia. He went ashore at the Pennefather River in the Gulf of Carpentaria, thus becoming the first authenticated European to reach Australian soil.

duyfken chart.

Cape York, Australia. Charted in 1606, and mistakenly labelled New Guinea.

Willem Janszoon followed the coast south, charting the coast as he passed it, before turning north and returning to Banda. At the end of his voyage, as all VOC Commanders were required, he turned his journal and all his notes and charts over to the company cartographer. His coastal survey of the west coast of what we now know as Cape York subsequently appeared on a VOC company chart.

This was the first time that any part of Australia had appeared on a chart.

In 1611, while Hendrik Brouwer was sailing from from the African Cape Colony to Batavia he discovered that it was quicker to first go south to the latitude of 40°S, thereby gaining the advantage of the ‘roaring forties’, and then follow this eastwards before turning north to Batavia. The VOC noted this time saving and gave new instructions to its commanders sailing from the Cape Colony to Batavia, requiring them to take the “Brouwer route”. While this was done in the interest of increased profit, it placed many more vessels in the latitude, and travelling in the direction of, Australia.

In October 1616, separated from the others boats he had sailed with, Dirk Hartog commanding the Eendracht unexpectedly found ‘various islands’ at latitude 26°S.

He made landfall at an island off the coast of Shark Bay, Western Australia, which is now called Dirk Hartog Island after him. His was the second recorded European expedition to find the Australian continent, and the first on the west coast. He spent three days exploring the area before leaving a pewter plate on a post to mark his visit. It bore the inscription;

On the 25th October, arrived here the ship Eendracht of Amsterdam; the first merchant, Gilles Mibais, of Luyck; Captain Dirk Hartog; of Amsterdam; the 27th ditto set sail for Bantam; undermerchant Jan Stoyn, upper steersman, Pieter Dockes, from Bil, Ao, 1616…

Hartog plate.

The Hartog Plate is now in the Rijksmuseum, Amsterdam.

Between 1616 and 1629, seven other VOC vessels travelling the Cape Colony to Batavia route found themselves on the West Australian coast; the Vyanen, Zeewulf, Dordrecht, Amsterdam, Leeuwin, Batavia and Gulden Zeepaert. The last of these undertook an extraordinary detour.

The Gulden Zeepaert had left the Netherlands in 1626 bound for Batavia. She was commanded by Francois Thijssen, and had on board ‘Supercargo’ Peter Nuyts, the vessels VOC merchant and also a member of the Council of the Indies.

In January 1627 the Gulden Zeepart came upon the south-west coast of Australia near Cape Leeuwin, so named after the VOC vessel that had met this coast in 1622. Peter Nuyts had also been aboard the Leeuwen on that occasion. Standing instructions to the Commander were to follow the Brouwer route, and if land was encountered, to head northwards and then on to Batavia. However, the Gulden Zeepaert, presumably yielding to the superiority of Nuyts, followed the coast south and then west. Incredibly they continued 1800 km eastwards, across the Great Australian Bight, as far as Ceduna, just 500 km west of Adelaide, before finally turning around and making for Batavia.

Not all VOC Australian discoveries were accidental. In 1623, the Arnhem and the Pera, followed in 1636 by the Cleen Amsterdam and Cleen Wesel, were despatched to further explore the ‘south lands’. These voyages charted the northern coast of Australia from the Gulf of Carpentaria westwards.

Prior to Abel Tasman’s Voyage, Dutch vessels had visited parts of the Australia coast on 20 occasions, and after each voyage the charts and journals were sent forward to the company cartographer.

Parts of Australaia known to the VOC prior to Abel Tasman’s voyage.

By 1642 the VOC had knowledge of approximately half of Australia’s coastline, yet they hadn’t set up a trading fortress there. All accounts of the country sent back to the Netherlands spoke of a barren land; and whilst there were people there, they had found nothing of value to trade.

In 1617, in the interests of securing their intellectual property, the VOC moved away from contracting their cartographic services, and engaged Hessel Gerritsz to work exclusively for them.

All charts and logs from returning VOC commanders were submitted to Gerritsz, where he collated them. He compiled the ‘south land’ discoveries into a single chart, which he added to as new information was received. The result, drawn in 1628, is a quite remarkable map of ‘Australia’ as we now know it.

Gerritsz chart.

Gerritsz chart of Australia, 1628 (this image loads slowly)