Independent development of ocean navigation

The Arabs developed it independently. By the time Vasco da Gamma arrived to the Indian Ocean, it was intensively navigated by the Arabs and other Muslim peoples. They "discovered" Madagascar and Indonesia, and had regular sea trade with India.

But it is not completely clear how to define "ocean navigation". (See the example of the Norsmen discussed in the comments). Another example is settling of Australia by the humans. We know it happened more than 50,000 years ago, but have no idea how this could happen. One can argue that this was not true "ocean navigation" but an island-to-island hopping. But navigation of the Polynesians was more or less like this as well. What kind of distances away from any shores or islands qualify as "ocean navigation"?

I would think the vikings would count because their navigation was based on the sun and stars just like those who followed them. The Vikings not only crossed the North Atlantic but they also went into the Mediterranean and Black Sea. And while they never discovered a sea route to India or China that should not detract from their accomplishments because no other contemporary Europeans did either. Not until the Renaissance (1498) when Vasco da Gama did so.

Question:
I am wondering about who can reasonably claim to independently have developed navigating oceans

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I would argue for 18th Century British clockmaker John Harrison. Nobody before him really could navigate the oceans. All of them only had half the picture. Even in the early 18th century the only accurate way to navigate the oceans was to follow the coastline. One can determine latitude from the sun and stars but not longitude. For longitude even in the early 18th century sailors still had to use "dead reckoning". You guessed wrong terrible things could happen.

Scilly naval disaster of 1707
the loss of four warships of a Royal Navy fleet off the Isles of Scilly in severe weather on 22 October 1707. Between 1,400 and 2,000 sailors lost their lives aboard the wrecked vessels, making the incident one of the worst maritime disasters in British naval history...... .
The disastrous wrecking of a Royal Navy fleet in home waters brought great consternation to the nation. The main cause of the catastrophe has often been portrayed as the navigators' inability to accurately calculate their longitude.7 Clearly, something better than dead reckoning was needed to find a way through dangerous waters. As transoceanic travel grew in significance, so did the importance of reliable navigation. This eventually led to the Longitude Act in 1714,

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The longitude problem: how we figured out where we are
Robert Mayhew of the University of Bristol tells of times when longitude went wrong. “A battle raged between Spain and Portugal in the 16th century over the Maluku Islands,” he said. A treaty between Spain and Portugal used a line of longitude in the Atlantic to divide the colonies between them. But it was unclear where the line fell on the other side of the world, so Spain and Portugal both claimed that the Maluku Islands were on “their side”. “Once you can plot longitude reliably, these sorts of disputes become capable of resolution,” Mayhew said.

There were many instances where explorers “discovered” the same island multiple times, particularly in the Pacific region, where 18th century navigators were obsessed with plotting the islands reliably.

“Optical illusions like heat haze led to land being claimed where none existed. One example of this could be Pepys Island, named after the famous English diarist. As far as we can tell, there’s no land anywhere near its reported location, so it probably doesn’t exist.”

Many had tried to solve this problem.

• Philip II of Spain offered a reward for a solution in 1567
• Philip III in 1598 offered 6,000 ducats and a pension,
• the States General of the Netherlands offered 10,000 florins in the early 1600s

After many maritime disasters due to navigational errors, in 1714 the British Parliament set up their own contest to incentivize the development of a way to determine longitude at sea. The Longitude Act of 1714.

John Harrison was the one who solved the problem. He was a wooden clock maker obsessed with his craft and the accuracy of his clocks. He theorized that if he could accurately measure time on-board a ship at sea the calculation of Longitude would be trivial. On November 18th 1761, after decades of trial and error and multiple prototypes, John Harrison successfully demonstrated a pocket watch, his H4, (4th of 5 models built by Harrison to solve the problem) Harrison's H4 demonstrated accuracy in determining longitude on an ocean voyage between the UK and Kingston Jamaica off by only 1.25 minutes, approximately one nautical mile.

While Harrison was forced to demonstrate his achievement in 4 successful sea trials he never received the prize (£20,000). In 1773 he was awarded £8,750 from Parliament for his achievements. This is largely seen as a **bias by the judges of the contest, and does not tarnish Harrison's accomplishment as his chronological based navigation method became the most widely used and accurate navigation technique into the modern era, until it was replaced by satellite navigation(gps).. and even today marine navigators regularly check their gps positioning with sexton and chronological navigation.

** Harrison was primarily a craftsman and the people judging his achievement were scientists. They just didn't respect his breeding, lack of education, lack of scientific training and really dismissed his accomplishments. The Scientific community backed a second method for determining longitude based purely on mathematics and the stars (angle between moon and stars). It was believed Harrison's technology approach was not as reliable as a purely scientific approach and thus not a complete solution worthy of the prize. The British Longitude prize was never awarded.

From: Comments

While I agree with the argument put forth that John Harrison is a good contestant for "individual with the greatest contribution to ocean navigation", certainly the British had reached "it works ok enough" ocean navigation well before his time, and moreover, the British don't have a claim to independent development of that technology, as they had too close contact with the Iberians who managed before. – Arno

@Arno, Thank you for the comment. The British ocean navigation didn't work "well enough". That's why they commissioned the contest and maintained a board of their scientists on the problem for more than six decades. A global concern like the British Empire in the eighteen century required more certainty than a best guess; as the Spanish Empire had ascertained when they were faced with the same problem 100 years earlier. This was a huge problem ocean going civilizations had struggled with for centuries.

From Pieter Gerkens: Please correct "You guessed wrong and you could end up 100's of miles from your destination and could not tell if you were 100 miles north or south of your destination without sighting a land mark or asking directions." as a simple sextant was sufficient to determine latitude much more accurately than that, by orders of magnitude.

Thank You. Removed that sentence. FYI first sextant was a result of the Longitude act of 1714. Commissioned by the Longitude board and developed by John Bird in 1759. Based on observations made by Thomas Campbell during sea trials of John_Hadley reflecting octant. This first sextant was heavy, made of brass, and needed to be braced on a clip attached to one's belt to use. More importantly was only part of the solution for telling time based on moon and star calculations which was key to finding longitude using a sextant. The astronomical charts also required to make longitude calculations likewise weren’t available until the mid 18th century also a result of the longitude act.

From @Mark Even an early mariner's astrolabe marked in degrees could get better than 75 miles north/south, and a sextant in the hands of a skilled user could get within a few hundred meters. It was only east-west location that has historically been a problem.

You're right, should've been east-west. Changed the blurb to give a historical event which inspired the Longitude Act. Thank You.