Blog
Understanding the Nautical Mile: The Mariner’s Unit of Distance
Understanding the Nautical Mile: The Mariner’s Unit of Distance
From ancient celestial charts to modern GPS systems, one unit of measurement has remained constant across the seas — and every seafarer must know it.
By Raymond Gold | Waterways News Editorial Desk | Maritime Education
In the world of maritime navigation, precision is not a luxury — it is a matter of life and safety at sea. Whether you are a deck officer plotting a course across the Atlantic, a pilot officer filing a flight plan, or a maritime cadet sitting your first professional examination, there is one fundamental unit of measurement that underpins everything: the nautical mile.
Yet despite its centrality to all things marine and aviation, the nautical mile remains poorly understood by many outside the profession. What exactly is it? Why does it differ from the ordinary mile we use on land? And why has it remained the global standard for over a century? Waterways News answers these questions in full.
“The nautical mile is not an arbitrary unit — it is carved from the very geometry of the Earth itself.”
What exactly is a nautical mile?
A nautical mile (abbreviated as NM or nm) is the standard unit of distance used in both marine and aviation navigation worldwide. Unlike the statute mile — the familiar unit of distance used on land in countries such as Nigeria, the United Kingdom, and the United States — the nautical mile is not derived from historical convention or old imperial standards. Its definition is rooted directly in the geometry of the Earth.
Specifically, one nautical mile is defined as exactly one minute of arc of latitude on the Earth’s surface. The Earth is divided into 360 degrees of latitude, and each degree is divided into 60 minutes. That means the circumference of the Earth is essentially 360 × 60 = 21,600 nautical miles — a fact that makes the nautical mile extraordinarily useful for navigators, since a degree of latitude on a nautical chart corresponds directly to 60 nautical miles, and one minute of latitude to one nautical mile.
KEY CONVERSIONS — 1 NAUTICAL MILE EQUALS
In metres 1,852 metres exactly
In kilometres 1.852 km
In statute miles ≈ 1.1508 land miles
In feet ≈ 6,076 feet
Why not just use kilometres or land miles?
The question is a fair one, particularly for students approaching maritime education for the first time. The answer lies in the relationship between the nautical mile and the Earth’s coordinate system. Because navigators work with latitude and longitude — a system based on degrees and minutes — the nautical mile offers an immediate and intuitive connection between a chart reading and a real distance.
If a navigator notes that two positions differ by 30 minutes of latitude, they instantly know the distance between them is 30 nautical miles. No conversion is necessary. Using kilometres or statute miles on a nautical chart would break this elegant relationship and introduce unnecessary opportunity for error — a dangerous outcome at sea.
This consistency holds true anywhere on the globe: the relationship between one minute of latitude and one nautical mile does not vary whether you are navigating the Niger Delta waterways, the Gulf of Guinea, the English Channel, or the South China Sea. That universality is precisely why the nautical mile has been adopted as the international standard by bodies including the International Maritime Organization (IMO) and the International Civil Aviation Organization (ICAO).
Speed at sea: the knot
At sea, speed is not measured in kilometres per hour or miles per hour — it is measured in knots. One knot is defined as exactly one nautical mile per hour. A vessel travelling at 12 knots covers 12 nautical miles every hour. This unit, too, has a history tied directly to maritime practice — early sailors measured speed by throwing a wooden float overboard and counting how many knots on a rope passed through their hands in a fixed time.
The short answer: anyone involved in maritime or aviation operations. Deck officers and marine pilots use nautical miles daily for course plotting, passage planning, and position reporting. Port and harbour authorities reference distances in nautical miles when coordinating vessel traffic. Search and rescue coordinators define search areas in nautical miles. Meteorologists and oceanographers use nautical miles and knots when describing weather systems affecting coastal and offshore waters.
For Nigeria specifically — a country with an extensive coastline along the Gulf of Guinea, a vast network of inland waterways including the Niger and Benue river systems, and a growing oil and gas maritime sector — the nautical mile is foundational knowledge for anyone working in or around the nation’s blue economy. From NIMASA-licensed officers to small-craft operators on the Lagos Lagoon, from river pilots on the Niger to offshore supply vessel crews, understanding this basic unit is the starting point for all professional maritime competence.
A note for maritime students
If you are currently studying for a professional maritime certificate of competency — whether at the Nigerian Maritime University, the Maritime Academy of Nigeria in Oron, or any other approved institution — expect the nautical mile and its conversions to appear in your navigation and chartwork papers. Memorise the key figures: 1 NM = 1,852 metres. Know that one degree of latitude = 60 nautical miles. And understand that speed at sea is always expressed in knots, never kilometres per hour.
These are not merely examination facts. They are the language of the sea — and knowing them fluently is the mark of a professional mariner.
Chief Raymond Gold is Co-Publisher and Research Reporter at Waterways News
Blog
Onigbinde Assumes MARAN Presidency, Vows to Rebuild Association, Raise Bar for Maritime Journalism
Onigbinde Assumes MARAN Presidency, Vows to Rebuild Association, Raise Bar for Maritime Journalism
By Okeoghene Onoriobe | Waterways News Correspondent
Newly-elected President of the Maritime Reporters Association of Nigeria (MARAN), Mr. Oluyinka Onigbinde, has outlined a reform-driven agenda anchored on institutional rebuilding, ethical journalism, member welfare, and deeper engagement with maritime industry stakeholders.
Onigbinde, Assistant Editor of Shipping Position Daily, emerged as the 15th president of MARAN following a keenly contested election held at the association’s elective congress in Apapa, Lagos last week Thursday. He defeated veteran maritime journalist Reverend John Iwori in a poll conducted under the supervision of the Lagos State Council of the Nigerian Union of Journalists (NUJ).
Speaking during an interactive session on Radio Nigeria shortly after his victory, Onigbinde described his emergence as a collective win for the association rather than a personal triumph, and stressed that the road ahead would demand unity, sacrifice, and accountability from all members.
“Leadership is not about age; it is about responsibility, maturity, and the ability to carry the hopes and expectations of the people,” he said, in what appeared to be a direct response to commentary about him being among the youngest presidents in the association’s history.
Reforms and Professionalism
At the heart of Onigbinde’s agenda is a commitment to institutional reform aimed at strengthening professionalism among maritime beat reporters and restoring MARAN’s relevance as a credible voice in industry and policy circles. He indicated that his administration would pursue expanded training and capacity-building programmes for members, alongside deliberate efforts to position MARAN as an active participant in maritime policy discourse.
“My dream includes strengthening professionalism among maritime journalists, improving members’ welfare, creating more training and capacity-building opportunities, and deepening engagement with industry stakeholders,” he stated.
The new president also placed ethical journalism at the centre of his reform vision, with a particular emphasis on mentoring the next generation of reporters covering Nigeria’s maritime sector.
“We intend to promote ethical journalism and ensure that younger journalists are mentored appropriately,” he said.
Reconciliation and Inclusivity
Beyond the reform agenda, Onigbinde pledged to heal divisions within the association that may have widened during the electioneering period. He gave assurances that his administration would run an inclusive ship, leaving no room for factional loyalties.
“My administration will be inclusive. There will be no room for party A or party B. Everybody must see themselves as part of this government regardless of who supported me or not,” he declared.
He disclosed that he had already reached out to his opponent, Rev. Iwori, immediately after the election results were announced, and expressed hope that both men would work together to advance the association. “I look forward to working with him and building stronger synergy to take MARAN to greater heights,” he said.
As part of his reconciliation drive, Onigbinde also announced plans to re-engage past presidents and long-standing members who had drifted from active participation in the association, noting that several former presidents had already signalled readiness to return following his election.
Flagship Programmes to Continue
The MARAN president reaffirmed his commitment to sustaining the association’s Annual Maritime Lecture, describing it as a critical platform for industry engagement and policy debate that his administration intends to strengthen further.
Nigeria Watch
MARAN’s health matters to Nigerian maritime journalism — and by extension, to the quality of public discourse around the sector’s development. An association that consistently produces well-trained, ethically grounded reporters is a strategic asset for institutions like NIMASA, the NPA, the NSC, and the Federal Ministry of Marine and Blue Economy, all of which depend on an informed media to build stakeholder trust and drive policy accountability.
Onigbinde’s stated emphasis on capacity-building, ethical standards, and stakeholder collaboration is well-calibrated. Whether the ambition translates into measurable outcomes will depend on the administration’s ability to mobilise resources, sustain member engagement, and resist the patronage pressures that have historically undermined associations of this kind. Waterwaysnews.ng will be watching
Portugal’s Seabed Energy Farms Points a New Way for Ocean Nations
By Ighoyota Onaibre | Waterways News Correspondent
Finland’s AW-Energy and a 14-partner European consortium have deployed WaveRoller technology off Peniche in a milestone that maritime and energy planners from Lagos to Abuja should be watching closely
Eight hundred and twenty metres off the coast of Peniche — a windswept fishing town on Portugal’s Atlantic seaboard long known for its big-wave surfing — something quietly extraordinary is happening on the ocean floor. Hinged panels, each the size of a large shipping container standing on end, are anchored to the seabed in 15 to 25 metres of water. As deep Atlantic swells roll in from the open ocean, the panels rock back and forth with the surge. Every tilt and recovery drives hydraulic fluid through onshore generators. The ocean is, in the most literal sense, doing the work.
This is not a laboratory experiment. It is the commercialisation of wave energy — one of the most elusive prizes in renewable power development — and it is happening now.
The Technology: How WaveRoller Works
The device behind the Peniche installation is the WaveRoller, developed by Finnish clean energy company AW-Energy. The first unit of the wave power farm was successfully installed on the seabed, marking the beginning of the commercial phase of clean electricity production.
The principle is elegantly simple. The technology consists of a vertical panel that moves with the sea currents, capturing energy that is transmitted to a hydraulic system and then to a power plant. Unlike offshore wind turbines, which are visible from the shore and exposed to storms, WaveRoller units sit beneath the surface, sheltered from the worst of the weather, anchored to the seabed by a foundation system engineered to handle the relentless pressure of open-ocean swells.
The device is installed 820 metres offshore from Peniche, and during the commissioning phase, operators collect data around the clock to monitor performance using motion, pressure, and strain gauge sensors engineered into its panel, foundation, and bearings. AW-Energy CEO Christopher Ridgewell has said the data received from the installation indicates the WaveRoller is operating well and performing in accordance with expectations.
The connection to the national grid runs via an onshore substation, meaning the power generated beneath the waves travels ashore through a submarine cable and feeds directly into Portugal’s electricity network — the same infrastructure that powers homes, hospitals, and factories.
ONDEP: Scaling Up to Commercial Reality
The latest and most significant chapter in Peniche’s wave energy story is the Ondas de Peniche project, known by its Portuguese acronym ONDEP. The ONDEP project has been awarded €19 million from the EU’s Horizon Europe funding programme to deploy a 2 MW wave energy array featuring four WaveRoller wave energy converters. The project commenced in October 2024 and will last five and a half years, encompassing the full spectrum of project activities — from design and manufacturing to testing, deployment, and operation.
Two megawatts may sound modest in an era of gigawatt-scale offshore wind farms, but the significance of ONDEP lies not in its size but in what it proves. The pilot wave farm will be installed and connected to the grid and will continue generating electricity for an additional eight years after the project’s official end (Energy Global) — a total operational horizon of more than thirteen years that will generate the long-term performance data the industry has long needed to attract serious infrastructure investment.
The ONDEP project will also establish a comprehensive, end-to-end European supply chain to support the deployment of gigawatt-scale wave energy across Europe and beyond, as a significant step towards the industrialisation of wave energy.
Ridgewell has described the project as the culmination of two decades of development work: “This project builds on two decades of hard work developing WaveRoller into a commercial asset. We’re excited to work on this collaboration together with the other partners to create a new industry in Europe.”
Led by Queen’s University Belfast, ONDEP involves 14 partners from Belgium, Finland, France, Italy, the Netherlands, Norway, Portugal, Spain, and the United Kingdom.
The breadth of that consortium — spanning universities, engineering firms, marine contractors, and grid operators — reflects the complexity of bringing an ocean energy technology from prototype to bankable commercial product.
Why Wave Energy Matters: The Case for the Unstoppable Resource
The appeal of wave energy, to engineers and energy planners alike, comes down to one word: predictability. Solar panels produce nothing at night and struggle on cloudy days. Wind turbines are idle when conditions are calm. But wave energy captured through the rhythmic motion of the sea offers one of the most consistent, predictable forms of renewable power on the planet. Unlike solar or wind, waves do not sleep. They do not stall. They do not depend on perfect weather.
This consistency is particularly valuable to grid operators trying to balance supply against demand around the clock. A power source that generates reliably through nights, cloudy seasons, and calm spells fills precisely the gap that intermittent renewables cannot. For coastal nations with energy deficits and long Atlantic-facing coastlines, it is a resource that literally never stops arriving.
The Africa Dimension: A $296 Billion Blue Economy Waiting
For Nigerian maritime and energy policymakers, the Peniche story carries a very direct message. Nigeria boasts an 853-kilometre coastline along the Atlantic Ocean and extensive inland waterways covering over 10,000 kilometres. Data from the Nigerian Maritime Administration and Safety Agency projects the value of Nigeria’s untapped blue economy potential at a stunning $296 billion. (Voice of Nigeria)
Apart from harnessing tidal and wave energy as part of Nigeria’s green transition, marine biotechnology, research and development in marine-based pharmaceuticals and bio-products are opportunities waiting.
Research has already begun to quantify the resource. A study evaluating Brass Creek in Rivers State found that the site is characterised by moderate to high significant wave heights and favourable wave periods, with annual mean wave power density reaching 31.42 kW/m and seasonal peaks observed during summer and autumn. The prevailing wave direction aligns with the Atlantic swell, further supporting the site’s suitability for wave energy extraction. The same study found that significant wave heights above 1.5 metres occur with a probability of 93.6%, underscoring the reliability of the resource.
Yet despite this documented potential, Africa has no commercial wave farms today — not one.
The instantaneous wave power resource of African waters has previously been estimated to be between 324 GW and 422 GW — a figure that dwarfs Nigeria’s current installed electricity generation capacity many times over. Investing in offshore wind, tidal, and wave energy can provide sustainable sources of electricity while reducing greenhouse gas emissions, according to analysts assessing Nigeria’s blue economy prospects.
Nigeria Watch: What the Peniche Milestone Means for Nigeria’s Marine and Energy Sectors
Portugal’s Peniche installation is more than a technology story. It is a policy signal — and Nigerian stakeholders, from the Federal Ministry of Marine and Blue Economy to NIMASA and the Nigerian Electricity Regulatory Commission, should take note of several dimensions.
The regulatory template. Portugal has not simply funded a project; it has built a framework — grid connection standards, seabed lease arrangements, environmental monitoring protocols — that took years to develop. Nigeria’s maritime regulatory architecture, currently being strengthened under the Marine and Blue Economy agenda, will need analogous structures if ocean energy is ever to attract private capital.
The financing model. ONDEP’s €19 million EU Horizon Europe grant was matched by a consortium of fourteen institutional partners. No single government carried the risk. Nigeria’s engagement with multilateral development finance — the African Development Bank, the World Bank’s IFC, and bilateral climate funds — offers a comparable pathway, particularly given Nigeria’s NDC commitments under the Paris Agreement.
The coastal community dimension. One of the stated objectives of the Peniche installation is ensuring that residents of Peniche benefit directly from the energy it generates. Nigeria’s coastal communities — in Bayelsa, Delta, Rivers, Akwa Ibom, Cross River, Lagos, Ogun, and Ondo states — have historically seen their maritime resources extracted without equivalent benefit flowing back. A wave energy programme conceived from the outset around local grid connection and community benefit-sharing would represent a meaningful departure from that pattern.
The port infrastructure opportunity. Eco Wave Power, a separate Israeli-Swedish technology company, is implementing a first 1MW project at a breakwater facility in Porto, Portugal, which is expected to be finalised during 2026. The Porto model — attaching wave energy converters to existing port infrastructure rather than deploying standalone offshore arrays — is directly applicable to Nigeria, where the Nigerian Ports Authority manages breakwater and jetty structures at multiple locations along the coast. NPA’s concession renewal discussions and its ongoing infrastructure modernisation programme would be a natural vehicle for piloting a comparable installation.
The Bottom Line
What Portugal has demonstrated at Peniche is not a proof of concept — that stage passed some years ago. What it has demonstrated is commercial viability at grid scale, backed by serious institutional money, operating under real regulatory conditions, with a business model that works.
For Nigeria, with its vast Atlantic coastline, its chronic electricity deficit, its expanding Federal Ministry of Marine and Blue Economy mandate, and its $296 billion blue economy prize still largely uncaptured, the question is no longer whether wave energy is technically possible. The question is whether the policy will, the institutional coordination, and the financing architecture can be assembled before another decade passes.
Peniche’s seabed is moving. Lagos’s energy planners should be too.
Onigbinde Wins MARAN Presidency in Keenly-Contested Election
Shipping Position Daily’s Assistant Editor defeats veteran journalist Iwori by seven-vote margin
By Okeoghene Onoriobe | Waterways News Correspondent | May 10, 2026
Oluyinka Onigbinde, Assistant Editor of Shipping Position Daily, has been elected as the new President of the Maritime Reporters Association of Nigeria (MARAN), following a competitive ballot conducted at the association’s congress on Thursday.
The election was supervised by a team from the Lagos State Council of the Nigerian Union of Journalists (NUJ), led by the Council Chairman, Mr Leye Ajayi, lending credibility and transparency to the exercise.
Onigbinde defeated veteran maritime journalist and clergyman, Reverend John Iwori, polling 20 votes against Iwori’s 13 votes from a total of 33 cast — a margin of seven votes that sealed his emergence as the incoming MARAN president.
A full slate of executive officers was also returned to steer the association through its new tenure. Obasi Sylvanus was returned unopposed as Vice President, while Fabian Anawo was elected General Secretary. Ojelabi Amina will serve as Assistant General Secretary, with Ayanfeoluwa Providence taking on the role of Public Relations Officer. Ruth Umuna was elected Treasurer, and Ambrose Okehi returned unopposed as Financial Secretary.
The new executive team is expected to champion professionalism, advance the welfare of maritime journalists, and foster greater cohesion among MARAN’s membership — a body whose coverage spans Nigeria’s ports, shipping lanes, blue economy governance, and the full breadth of the nation’s maritime trade ecosystem.
Nigeria Watch
MARAN is the foremost association of journalists covering Nigeria’s maritime sector, and its leadership transitions carry significance beyond internal association politics. The quality, independence, and professionalism of maritime journalism directly shapes how key stakeholders — terminal operators, freight forwarders, shipowners, regulators and policymakers — receive and act on information affecting the sector.
Onigbinde’s emergence from the stable of Shipping Position Daily, one of Nigeria’s most specialised maritime trade publications, signals that the incoming leadership brings deep sector knowledge to the role. For maritime trade stakeholders, a well-led MARAN means sharper scrutiny of port governance, stronger accountability coverage of agencies like NPA, NIMASA, NSC and NIWA, and a more informed media environment for the industry at large.
-
Oil and Gas2 months agoTantita’s Pipeline Deal: $144m Contract, Rising Output, and the Questions that Deserve Answers
-
Blue Economy3 months agoNigeria’s Coast Guard Bill: A Solution in Search of a Problem?
-
MARITIME TRADE & SHIPPING2 months agoWorld’s Largest Container Ship Sets New Maritime Record with 22,233 TEUs on Single Voyage