Minimalist Navigation

Back in the day a similar argument was made when navigators started using the astrolabe. “Real” seaman didn’t need it. Skilled navigators used DRs and parallel sailing, They could estimate latitude within about 30 minutes just by eyeball.

Ditch the GPS and while your at it get rid of the sextant and a compass is not really the necessity a lot of people think it is.

The one thing the early Vikings wouldn’t sail without was the sounding lead, so you might want to hold onto that. Maybe a sunstone for cloudy days.


Leiv Eriksson discovers America" ​​is the name of Christian Krogh’s famous painting.
But did he navigate right – and after the sun stone?

“Leidarstein” was a crude form of compass used by Vikings as early as the 900’s AD:

The Vikings may also have used a Sunstone as a compass:

According to The Conquest of the North Atlantic by Marcus the one item the Vikings would not sail without was the lead line. Otherwise too dangerous to approach the coast without a good position.

Before Leiv Eiriksson was Bjarni Herjólfsson

Yes he sighted land when blown of course on a voyage from Iceland, but did not land there.
His destination was Greenland. He turned North and reached the Norse settlements, where he told about the land to the South West.
Leiv Eriksson, like his Father Erik the Red before him, brought people with him to establish a settlement on the newly discovered land and bring timber with him back to Greenland.

A magnetic compass for oceanic voyages does not help much without a magnetic deviation chart.

Somewhere I was reading that Columbus had problems to explain to his mates why the sun’s noon position and the compass did not show the same direction during his first Atlantic crossing.
Between Norway and NE-America, the deviation changed by about 20° for the Vikings.

Neither Columbus nor the Vikings could know about magnetic deviation, they had to use the noon sun.

Simpler to calibrate against Polaris. Once one has a compass, it seems likely that any long-distance traveller would soon become aware of variation. It’s possible that it’s like the (possibly apocryphal) “3rd condiment” mystery: something considered too obvious to be worth writing down.

Columbus was either noticing variation, or Polaris revolving around the pole. The latter would be detectable over the course of a night, but by the same token should have been well known: Polaris being farther from the pole back then, and even farther in the preceding centuries.

From las Casas’ summary of Columbus’ journal, the following entries mentioned the compass concerns:

Monday 17 September
He steered his course W and they would have made more than 50 leagues during the day and night; he only reckoned 47. The current was assisting them. They saw a good deal of weed, very frequently, and it was a rock weed and came from westward. They reckoned they were near land. The pilots took the north and marked it and found that the compass needles veered NW by a full point, and the sailors were fearful and anxious and did not say why. The Admiral sensed this and ordered them to mark north again at dawn and they found that the compasses were true. The reason was that it is the star that appears to move, not the needles.

Sunday 30 September
He steered his course W. He made 14 leagues during the day and night between periods of calm; he reckoned 11. Four reed-tails came to the ship, which is a sure sign of land, because so many birds together is a sign that they had not strayed or were lost. Four gannets were seen on two occasions; much weed. He notes that when night falls the stars which are called the Guards are beside the western arm; and at sunrise they are on a line below the arm to the NE, so that it appears that throughout the night they only move three lines, that is 9 hours, and this is the case every night; this is what the Admiral says at this point. Furthermore, at nightfall the compass needles point a quarter NW, and at sunrise they are right on the star. From which it seems that the star appears to move, like the other stars; and the needles always seek the truth.


From what I’ve read compass variation was ignored. Rhumb lines on portolan charts were compass courses to be steered and on some portolan charts were distorted such that a single compass course could be steered between ports without adjusting for variation.

Columbus wouldn’t have needed to know what the change in variation was. If the same course is steered across the same destination would be reached. Changes in variation would be difficult to sort out from currents and other sources of error.


To sail the oceans, modern ships use the orthodromic path (when ever possible); the loxodromic path is only used for short distances, where the distance differences may be just yards.

The boats of the Vikings or Columbus could only sail with the winds. Neither calculated orthodromic nor loxodromic routes could have been sailed normally.

The Vikings had to sail the northern borders of the North Atlantic depressions to arrive at Greenland or even NE-America. Whether these were accidental one-way trips, with only exceptional returns to Norway… I do not know.
Columbus had to sail the trade winds, down at <20° latitude, and later return to Spain north of the Acores anticyclone; this was known (but possibly not well understood) then.

To calculate any route, it is necessary to know the destination.

  • The Vikings, without a compass, were probably just incidentally blown to where they arrived.

  • Columbus planned to sail to ‘India’ (then including South East Asia); it seems he never understood (or accepted) that he discovered a then unknown continent America (later, another Italian, Amerigo Vespucci, corrected this).

With these large, not really predictable detours, I do not understand why magnetic deviation (or compass variation) should not influence the outcome or should not have troubled the officers on Columbus’ first voyage (it seems they rapidly learned…).

I don’t see why a navigator using a compass necessarily would need to know magnetic variation.

Ignoring currents, winds, steering errors, limits of sailing vessels etc to make it simple; if a course of 270 degrees magnetic takes a vessel from point A to point B than a course of 090 degrees magnetic will be the return course.

The resultant track would not be a rhumb line when plotted because of changes in variation but it would, in principle at least, get the vessel where it was going and back.

From ChatGPT:

My vote for the bravest minimalist navigators goes to the 4 gents in the ICW on a pontoon boat who flagged me down to ask for directions. Their chart consisted of a paper placemat from Denny’s that looked like this:


Using navigation instruments and tools is about increased efficiency. Minimum requirements are driven by an incentive to lower losses and increase production.

Using a sextant is more efficient than DR and GNSS more efficient still and so forth.

The Vikings were traders and able to sail to far away destination of their choice on repeat voyages, not just “blown to where they arrived”:

They did have a rude compass in the form of their “leidarstein” (see post # 2)
But they may also have had other means, especially for the open sea routes between Norway, Iceland and Greenland:

They did so over centuries (800-1100 AD) and left their mark on the far flung countries where they settled, from Greenland to Sicily:

The name Viking is said to originate from “Vika”, the Old Norse name for what is today’s Oslofjord, especially the east side of the fjord.
I.e. Viking = someone from Vika.

BTW; The name has been revived in the name for the newly established county; Viken:

PS> Now in the process of being split up into it’s original three counties.

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Apart from the navigational aspects of determining a given course, I believe they had some flexibility in the actual sailing. To use the reconstruction Draken Harald Hårfagre as an example, her skipper mentions “She has no keel, but when speed is built up, there is some windward lift from the shape of the hull. Approximately 50-60 degrees is possible in good conditions, but normally it will be 70-80 degrees over ground.” I believe the estimated polar diagrams for caravels suggest a similar range. Beating to windward might not be particularly productive, but they would have more flexibility than being driven purely with the wind.


For those of you old enough to remember This Old House with Steve Thomas, you might be surprised to learn that he was a sailor. The Last Navigator — Steve Thomas - Official Website I stumbled across a picture of him sitting on a dirt floor of a hut while researching various methods of navigation. I guess this would be the tropical version of the vikings?


Navigating across oceans is not something that started with the Vikings.
The ancient Phoenicians sailed the Mediterranean as early as 1500 BC and may have reached as far as the British Isles:

Arab Dhows sailed far and wide in the Indian Ocean, East Africa and as far as Southern China from abt 250 BC:

The great Polynesian explorations and settlements in the Pacific started even earlier, with the better known “second wave” from around 1500 BC:

PS> Steve Thomas appeared to have been most occupied with Micronesia.

Thor Heyerdahl tried to prove that some migration to Polynesia had been by Balsa rafts from S.America:

He also tried to prove and that there had been ancient migration from North Africa to the Americas long before the Vikings:

You are correct, they definitely could sail courses other than dead downwind. I suspect they really tried to avoid anything higher than a beam reach though. If you read old accounts, if they missed a port and had to get back upwind they were in a fix.

Not really navigation but sailing on the Nile the prevailing wind is opposite to the current greatly aiding a dhow beating to windward.

Go ENE on At&t until you reach T-mobile, turn NNE and sail until you can make out Port Fourchon on the Verizon.


Is that the new version of “platform jumping”??