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Nab Tower

The Nab Tower is a cylindrical and structure located in , approximately four miles east of the Isle of Wight at coordinates 50°40′N 0°57′W, originally built in 1918 as a anti-submarine defense outpost but repurposed as an unmanned after the war. Designed by civilian engineer G. Menzies and constructed in Shoreham, , at a cost of £1 million, the tower measures 90 feet (27 meters) in height and 40 feet (12 meters) in diameter, featuring a honeycombed base for stability. It was intended as one of eight interconnected towers linked by nets to block German U-boats from accessing the , but the in 1918 rendered the project obsolete before completion; although a second tower was also completed, only the Nab Tower was deployed. Towed to its current position over the Nab rocks in 1920, it replaced a that had served there since 1812, providing navigational guidance to vessels entering shipping channel. Initially manned by lighthouse keepers until automation in 1983, the tower was upgraded with solar panels in 1995 for power and underwent a major refurbishment in , during which its corroded exterior was replaced with concrete, slightly reducing its height. Now remotely controlled from , , it continues to function as a key landmark, often described as "Britain's oddest " due to its unusual military origins and isolated offshore position. The structure has faced notable incidents, including a collision with the refrigerated cargo vessel Dole America on November 7, 1999, which damaged the tower's base and temporarily stranded the ship, as detailed in the official Marine Accident Investigation Branch report. Its enduring presence highlights the evolution of coastal defense strategies and navigational aids in British .

Origins and World War I Role

Anti-Submarine Defense Concept

During , German U-boats posed a severe threat to Allied merchant shipping in the and , sinking over 500 ships between February and April 1917 alone and averaging 13 vessels daily by late April, which jeopardized Britain's vital supply lines. In response, the British Admiralty established an Anti-Submarine Division in November 1916 under Admiral John Jellicoe to coordinate defensive measures, including the development of innovative fortifications to protect key coastal approaches. Civilian engineer Guy Maunsell proposed a strategic concept involving a chain of eight steel and concrete towers positioned across to block ingress, linked by steel nets to ensnare or deter U-boats attempting to navigate the narrow waters. Each tower was designed to mount two 4-inch guns for and searchlights for nighttime detection, forming an integrated barrier that would force submarines to surface or detour, exposing them to naval patrols. The Admiralty approved the prototype, estimated to cost £1 million, but the Armistice on 11 November 1918 halted further construction after only the Nab Tower was completed. This single structure was later repurposed as a lighthouse in 1920.

Design and Construction

The Nab Tower was designed as a prototype for a series of offshore defensive structures intended to form a barrier against submarine incursions in the English Channel. Its innovative engineering featured a cylindrical steel tower rising 27 meters (90 feet) high and 12 meters (40 feet) in diameter, supported by a hollow concrete base measuring 24 meters (80 feet) in thickness, shaped with pointed bows and stern to facilitate towing. The structure's cylindrical form enhanced its durability against offshore conditions, while the steel framework was clad in concrete for added protection and stability. Central to the design was the honeycombed base, which incorporated 18 watertight compartments to provide during transport and allow controlled flooding for positioning on the . This compartmentalized system ensured the tower could while being towed and then sink stably with a slight northeast tilt once in place, optimizing its role in the planned anti-submarine network. The base's prioritized both flotation and secure anchorage, reflecting the Admiralty's emphasis on modular, relocatable fortifications. Construction took place at Shoreham Harbour under supervision, where approximately 3,000 civilian workmen fabricated the in using and sourced for wartime urgency. The project, codenamed part of the M-N scheme, was completed by , though the halted further towers. Planned defensive features included internal quarters accommodating up to 100 personnel, multiple gun platforms for anti-submarine weaponry such as 4-inch guns, all integrated into the tower's multi-level interior—though these were never realized due to the war's end.

Deployment and Early Operations

Towing to Nab Rocks

Following the Armistice of 1918, decided in 1920 to repurpose the unfinished Nab Tower, originally constructed as an anti-submarine defense, by sinking it as a replacement for the aging Nab Lightvessel at the eastern entrance to . This decision addressed the need for a more stable in the hazardous waters east of the Isle of Wight, where the lightvessel had marked the Nab Rocks since 1812. On September 12, 1920, the approximately 10,000-ton concrete structure, measuring 90 feet in height and 40 feet in diameter with an 80-foot-diameter hollow base, was towed approximately 41 miles from Shoreham Harbour to the Nab Rocks at coordinates 50°40.075′N 00°57.155′W using two powerful paddle-wheel tugs. The operation required careful planning to navigate the tower through the harbor entrance, which offered only minimal clearance, before proceeding across the English Channel. Upon arrival, valves in the base compartments were opened to flood the interior with , initiating the controlled sinking process over the for stability. As water filled the honeycomb-structured base, the tower settled onto the with a slight groan and jerk, resulting in a permanent 3-degree tilt to the northeast. The relocation faced initial challenges, including weather delays that postponed the towing until calm conditions prevailed to ensure safe passage and precise positioning. Engineers monitored the descent closely amid anxious moments, adjusting for the uneven seabed to achieve the desired orientation over the shoal, ultimately securing the structure without major incident.

Initial Lighthouse Service

Following its positioning over the Nab Rocks in September 1920, the Nab Tower was commissioned as a by , replacing the longstanding Nab Lightvessel that had marked the hazard since 1812. The structure was fitted with a central lantern housing an gas-filled incandescent bulb, producing a single white flash every ten seconds. It was manned by a crew of three keepers—a principal keeper and two assistants—who served monthly rotations, with relief vessels from delivering provisions and personnel. The tower's primary role was to warn vessels of the dangerous Nab Rocks, a shallow reef east of the Isle of Wight, guiding shipping through the deep-water channels of the eastern approaches to and harbors. Its light had an initial visible range of 12 nautical miles, providing a critical daytime and nighttime in an area prone to dense traffic and fog. Daily operations involved the keepers maintaining the lantern and associated equipment, activating a fog horn during poor visibility to emit warning blasts, and managing the tower's self-contained systems for water and waste. The living quarters, originally designed for up to 100 military personnel during its wartime conception, were adapted into compact individual spaces for the small crew, including sleeping areas, a galley, and storage, ensuring sustained habitation offshore. In 1929, assumed full responsibility for the tower's operation, securing its long-term use as a dedicated navigational independent of its prior military oversight.

Service

Armament Installation

At the onset of , the Royal Navy upgraded the Nab Tower to adapt it for defensive purposes. Two 40 mm anti-aircraft guns were installed on the tower's roof, enabling it to engage low-flying aircraft threatening shipping in . These guns, a staple of British light anti-aircraft defenses, were used to defend against aerial threats. The tower functioned as a Royal Navy signal station, where personnel monitored Solent traffic and coordinated local defenses against potential incursions. This military role involved lighthouse keepers from Trinity House alongside Royal Navy signal station staff to handle both navigational signaling and defensive duties.

Combat Engagements

During World War II, from 1940 to 1945, the Nab Tower's crew, consisting of Royal Navy gunners alongside Trinity House lighthouse keepers, actively defended the Solent approaches using two 40mm Bofors anti-aircraft guns mounted on the structure. These engagements primarily targeted Luftwaffe aircraft conducting reconnaissance or bombing runs over the eastern Solent. The tower's defenses were credited with independently shooting down three German aircraft and contributing to the downing of a fourth in coordination with a passing Royal Navy vessel, demonstrating the effectiveness of its isolated position in disrupting enemy air activity. As an Admiralty Signal Station, the Nab Tower integrated into the broader defensive network, where its elevated vantage point enabled the spotting of incoming threats and the transmission of signals to coordinate responses from nearby fortifications and patrols. This role extended beyond direct fire, supporting offshore and coastal batteries in maintaining vigilance against air and potential naval incursions into the vital shipping lanes. The guns provided rapid-fire capability suited to low-level aerial threats common in the region. The tower's exposed location in the subjected the crew to ongoing challenges, including frequent air raid alerts and the harsh environmental conditions of living in rudimentary tin huts atop the steel cylinder—marked by biting winter winds, sweltering summers, and relentless sea noise that complicated operations. Despite these pressures and instances of near-misses from enemy or bombs, no successful direct attacks damaged the structure itself, allowing it to remain operational throughout the conflict without major interruptions. With the Allied victory in in , the Royal Navy demobilized its presence at the Nab Tower by late that year, removing the guns and restoring the site exclusively to duties under management. This transition marked the end of its military role, shifting focus back to amid postwar recovery efforts.

Post-War Lighthouse Operations

Manned Era and Automation

Following the end of in 1945, the Nab Tower continued its role as an offshore , staffed by three keepers who rotated in one-month shifts to maintain the light and ensure safe navigation into the deep-water channels for and ports. The keepers' daily routines involved meticulous maintenance of the lighting system, which used lamps until . Supplies such as food and were delivered fortnightly by boat and stored in the tower's base, while meals were prepared on a -fired Rayburn amid the constant scents of , , and . Life on the Nab Tower demanded significant adaptations to its unique structure, which featured a permanent 3-degree tilt from its 1920 deployment and an iron construction that caused the entire building to shake during heavy seas. Despite these challenges, keepers grew accustomed to the motion and the extreme temperatures—freezing in winter and sweltering in summer—finding relative luxury in individual bedrooms and a , amenities uncommon in other lighthouses where shared bunks were standard. The profound isolation fostered a disciplined routine focused on vigilance, with the offshore location limiting external contact to relief visits and occasional radio communication, underscoring the required for the role. In 1983, the tower underwent , converting it to an unmanned with the installation of an acetylene-powered backup light on a small red octagonal tower to ensure redundancy for the primary electric system. As part of this project, a landing pad was constructed on the tower's to facilitate remote maintenance access, along with an internal caisson for structural reinforcement. assumed full operational control and acquired the freehold in 1984, marking the end of the manned era and enabling centralized monitoring from their Harwich headquarters.

Key Incidents and Minor Upgrades

On 7 November 1999, the Liberian-registered refrigerated cargo Dole America collided with the Nab Tower while outbound from bound for , resulting in structural damage to the tower's base. The incident caused superficial and internal damage to the tower's foundation, though the sustained more severe hull breaches, leading to a cargo spill and grounding nearby. Repairs to the Nab Tower were completed in , including reinforcement of the base to address the collision-induced vulnerabilities and restore full operational integrity. This work ensured the structure's continued stability amid ongoing exposure to harsh marine conditions. Among minor upgrades, the installation of solar panels in 1995 enhanced power reliability by reducing dependence on traditional sources and minimizing maintenance needs for the automated system. Maintenance challenges persisted due to from constant saltwater , which accelerated on the and components. Periodic inspections were conducted primarily via helicopter to access the remote offshore site, allowing engineers to assess and mitigate deterioration without manned occupancy. Operational continuity was maintained through unmanned remote monitoring from Trinity House's Planning Centre in Harwich, Essex, enabling real-time oversight of the light, power systems, and beacons to ensure uninterrupted service.

Modern Refurbishments

1983 Automation and 1995 Solar Conversion

In 1983, the Nab Tower transitioned from manned operations to full , ending the requirement for three lighthouse keepers who had maintained the since 1920 and were relieved monthly by . This upgrade replaced the existing manned electric with an automated acetylene-powered beacon housed in a new prefabricated red octagonal lantern tower, enabling remote monitoring from Trinity House's control center in , . Concurrently, the constructed a helicopter landing pad atop the structure to facilitate periodic inspections and maintenance without on-site personnel, prior to Trinity House acquiring full ownership in 1984. The aligned with Trinity House's broader initiative to lower operational expenses through keeper reductions and minimized logistical demands for crew rotations. By 1995, the tower's power infrastructure was modernized through the installation of photovoltaic panels, converting the from acetylene-powered operation to a fully -powered operation that sustains the lighting and ancillary systems. This shift eliminated the need for fuel resupply voyages, promoting greater long-term reliability in the remote offshore location. The integration supported a new optic displaying a flashing white light visible for approximately 12 nautical miles, ensuring seamless continuation of navigational services within Trinity House's automated network.

2013 Major Overhaul

In 2013, commissioned to lead a major refurbishment project for the Nab Tower, addressing extensive that had compromised the structure's upper levels and , with the goal of extending its by at least 50 years. The initiative built on prior concerns identified during operations, ensuring the tower could continue as a reliable aid. Work commenced in mid-2013 under a design-and-build contract valued at £0.6 million. The core structural interventions involved shortening the tower from its original 27-meter height to 17 meters through the of deteriorated upper sections and timber elements. Internal was repaired extensively, followed by the application of a protective encasement over the remaining substructure, including a 75 mm spray-applied layer and precast edging units to enhance durability against the marine environment. The iconic red atop the tower was dismantled and temporarily relocated to the shoreline to facilitate these modifications. During the refurbishment, a new LED was installed, providing a flashing white light visible for 12 nautical miles. Given the tower's isolated position on Nab Rocks in the , logistics posed significant challenges amid frequent harsh weather and tidal constraints. relied on deliveries for heavy materials and a temporary 25-meter boom crane for section removal, supplemented by support where feasible, while workers endured 45-minute commutes from the . A new aluminum access door and internal ladder were also installed to improve future maintenance efficiency. The refurbishment concluded successfully in 2015, enabling the tower's prompt recommissioning as an unmanned lighthouse with enhanced resilience and reduced ongoing maintenance needs. This overhaul preserved the structure's navigational function while minimizing operational interruptions during the process.

Current Status and Significance

Technical Specifications

The Nab Tower stands at a height of 17 meters above mean high water following its reduction from 27 meters during the 2013-2015 refurbishment. Its base features a broad cylindrical structure with a of approximately 12 meters at the tower level, supported by a larger foundation that measures approximately 60 meters across at the , narrowing to 15 meters at the tower base. The structure exhibits a characteristic 3-degree tilt toward the northeast, a result of its original positioning in 1920. The total weight of the steel and concrete components is approximately 4,500 tons. The lighting system consists of a LED lantern mounted at the focal height of 17 meters, producing a flashing white light every 10 seconds with an intensity of 2,850 and a visibility range of 12 nautical miles. This setup ensures reliable illumination for vessels navigating the eastern approaches to . The tower is powered by solar panels installed during the 1995 conversion, enabling autonomous operation without reliance on external electricity. Additional navigational aids include an (AIS) with MMSI 992351136 for vessel tracking and a RACON responder that transmits the identifier "N" on displays to aid identification in poor visibility. Structurally, the tower rests on a honeycomb-patterned base with multiple flooded compartments that enhance stability on the Nab Rock seabed at a depth of about 20 meters. Remote monitoring from Trinity House's Planning Centre in assesses corrosion, structural integrity, and environmental factors to maintain operational safety.

Navigational and Cultural Role

The Nab Tower serves as a vital in the eastern , guiding vessels into the deep-water channels leading to and harbors while marking the hazardous Nab Rocks to prevent groundings and wrecks. Positioned approximately four miles east of the Isle of , it replaced the Nab Lightvessel in 1920 and continues to support safe passage through the busy approaches, where heavy maritime traffic navigates narrow lanes amid shifting sands and rocky outcrops. Maintained and remotely monitored by from its Planning Centre in , , as of 2025, the tower's automated light remains essential for mariners in all weather conditions, ensuring compliance with international standards. Culturally, the Nab Tower holds a prominent place as an iconic maritime landmark, visible from the coast and the eastern shores of of , symbolizing the region's seafaring . It gained cinematic fame in the 1951 Hammer film The Dark Light, where it was depicted as the isolated setting for a gang of criminals seizing control, blending thriller elements with the tower's remote, foreboding atmosphere. This portrayal, filmed on location, underscores its enduring allure in popular media, evoking themes of isolation and intrigue amid the Solent's waters. The tower's legacy embodies engineering innovation, originally constructed in 1918 as a prefabricated anti-submarine defense platform, and demonstrates resilience through , when it withstood the era's naval threats while functioning as a . Despite occasional public fascination—sparked by its unique history and dramatic silhouette—access remains severely restricted due to its offshore remoteness and operational sensitivity, limiting visits to rare maintenance expeditions. Looking ahead, has planned ongoing monitoring of impacts, including rising sea levels, to assess potential effects on the tower's structural stability and navigational efficacy amid environmental changes.

References

  1. [1]
    The story of the Solent's Nab Tower lighthouse
    ### Summary of Key Facts About the Nab Tower
  2. [2]
    Solent Landmarks
    The Nab Tower is essentially a steel and concrete cylinder, it was built in Shoreham, Sussex, in 1918 at a cost of £1m. The imposing 90ft (27m) tall, 40ft (12m) ...Missing: facts | Show results with:facts
  3. [3]
    Contact made by refrigerated cargo vessel Dole America ... - GOV.UK
    Jan 23, 2015 · On 7 November 1999, Dole America, a Liberian-registered refrigerated cargo vessel, collided with the Nab Tower in the eastern approaches to The Solent.
  4. [4]
    The German U-Boat Campaign Of WW1 That Almost Broke Britain
    On 23 April 1918, British naval forces attacked U-boat bases at Ostend and Zeebrugge. By the Armistice, the U-boat threat had been neutralised. Photographs ...Missing: Tower defense concept Guy Maunsell Solent English Channel
  5. [5]
    The story of the Solent's Nab Tower lighthouse - BBC News
    Jun 23, 2016 · Once described as "Britain's oddest lighthouse", the Nab Tower is an unusual maritime landmark upon which few have set foot.
  6. [6]
    Nab Tower Lighthouse | Trinity House
    Nab Tower Lighthouse was built in 1918 as part of a series of unfinished First World War defences, and then used from 1920 to replace the Nab Lightvessel.
  7. [7]
    Iconic Nab Tower's history spans a century in The Solent
    Jul 25, 2021 · Visible to the east of the Isle of Wight, the Nab Tower was planned for anti-submarine protection in The Solent in the First World War.
  8. [8]
    [PDF] NAB Tower Lighthouse Its 1916, the British are loosing to much s
    By the time anti submarine equipment was installed the cost of the first two 92ft high towers had reached 2.5 million, a huge sum in those days. On the 11th ...Missing: Maunsell estimate
  9. [9]
    Concrete Curiosities - Edition 5 - The Mystery Towers of Shoreham
    Dec 24, 2023 · Nab Tower. Having completed Tower No. 1 at great expense, it was decided that the structure was ideal to replace the Nab Rock Lightship ...Concrete Curiosities... · Background · Mystery Tower No. 2 (et Al)
  10. [10]
    [PDF] Nab Tower Lighthouse (Straits of Dover East of the Isle of Wright)
    After much thought it was decided to use the solitary "white elephant" to replace the old Nab Light Vessel by sinking it at the eastern end of the Spithead ...
  11. [11]
    Nab Tower - Wikishire
    Jan 16, 2023 · The Nab Tower is a tower in the Solent originally planned for anti-submarine protection in the Solent in the First World War, and now a lighthouse.
  12. [12]
    The Nab Tower - jabblog
    Mar 21, 2024 · In 1920 two or five tugs, according to the source of your choice, towed the tower to the Nab Rock, four miles off the Isle of Wight at the ...
  13. [13]
    WWII Defence Structures - Groups | Britain From Above
    Two anti-aircraft guns were mounted on the fort's roof during WW2. The fort was also used by the Royal Navy Auxiliary Service. Kentishman. Monday 20th of March ...
  14. [14]
    USA Bofors 40 mm L/60 Model 1936 - NavWeaps
    Jun 2, 2025 · This weapon was used on almost every major USA and UK warship of World War II and was a very potent AA gun. These guns are recoil operated and use a monobloc ...Missing: searchlights | Show results with:searchlights
  15. [15]
    [PDF] Black Jack - Southampton Branch World Ship Society
    The Nab Tower thence became an offshore lighthouse, and during the Second World War was armed with two 40mm Bofors guns, which were credited to shooting down 3.
  16. [16]
    Renovation of Nab Tower lighthouse begins | News - Maritime Journal
    Trinity House occupied part of the tower from 1920 onward, installing a light to replace the Nab lightvessel, with the structure remaining under the control ...Missing: decision repurpose
  17. [17]
    [PDF] General Lighthouse Authorities Aids to Navigation Review 2020 to ...
    Mar 3, 2021 · AtoNs provided: 5 lights, 7 Buoys, 2 Beacons, 1 Racon, 8 AIS. ... NAB TOWER. LIGHTHOUSE. 50° 40.075' N. 000° 57.155' W. Fl 10s. 12. Horn (2). 30s.
  18. [18]
    Historic Nab Tower in The Solent to be given a makeover | Daily Echo
    Aug 13, 2012 · Trinity House occupied part of the tower from 1920 onward, installing a light to replace the Nab light-vessel, with the structure remaining ...
  19. [19]
    Lighthouses of the Isle of Wight | Red Funnel Ferries
    Nab Tower Lighthouse ... The offshore lighthouse became automated in 1983 and is now operated from a Trinity House control room in Harwich, Essex.
  20. [20]
    Nab Tower - Lighthouse Accommodation
    It was towed out from the harbour to its new position near the Nab Lightvessel on 13th September 1920. ... In 2013 Trinity House undertook a major refurbishment ...<|control11|><|separator|>
  21. [21]
    Lighthouse Service - Hansard - UK Parliament
    Jul 13, 1987 · The Engineer-in-Chief outlined the potential savings from possible keeper reductions and running costs and eventual discontinuance of the fog ...
  22. [22]
    Nab Tower has a serious make-over - Practical Boat Owner
    Aug 8, 2013 · The tower will be equipped with a fixed light with a 12 nautical mile range, together with AIS and RACON beacons. The work is scheduled to be ...Missing: 2000s | Show results with:2000s
  23. [23]
    Bam restores some coastal military history before it's too late
    Sep 11, 2013 · ... Nab Tower became obsolete before it was deployed. ... Since 1983 it has been unmanned and was converted to solar power operation in 1995.
  24. [24]
    [PDF] TRINITY HOUSE CLIMATE CHANGE ADAPTATION REPORT 2016
    *The twelve lighthouses with boat landings at risk are: Beachy Head, Casquets, Coquet, Godrevy, Hanois, Longships,. Longstone, Nab Tower, Needles, Round Island, ...Missing: initial | Show results with:initial