Arming the fleet – the network that supplies munitions to the Royal Navy

Without munitions, the Navy would be toothless and of limited value. To fully arm the fleet requires a lengthy logistic chain of specialists and bespoke facilities. In this, the second of a 2-part article looking at naval support infrastructure, we examine the system that provides conventional munitions to the RN.

There are seven Defence Munitions (DM) sites in the UK that receive, store, maintain and issue (RSMI) general munitions (GM) and complex weapons (CW) for the UK armed forces. Six of the seven sites are either dedicated to RN needs or play a significant part in providing munitions to the fleet. Although a relatively low profile part of the defence infrastructure, the efficiency of the DM organisation has a big impact on the readiness and capability of the RN.

In broad terms, munitions arrive at the DM sites from the original manufactures and are stored in bunkers. Depending on the complexity of the weapon, they may need assembly and then regular inspections and maintenance before being prepared for issue to the fleet. From the bunker or weapons laboratory, the items are transported by road or rail to ammunitioning jetties where they are either loaded directly onto ships alongside or put on lighters to be taken out for loading onto moored warships. The munitions remain secure in specifically designed magazines onboard active warships or submarines until they are either expended in combat or training. The process is reversed for unused munitions which must be unloaded and returned to the DM stores when vessels go into maintenance or refit. The DM sites must also manage the safe disposal of obsolete and life-expired munitions.

Preparation and storage of munitions follow strict procedures and each type of weapon requires bespoke containers and cradles for transport and delivery. Modern explosives are inherently safer than those of the past with the advent of insensitive munitions which should not explode if subject to shock or fire.

Developments in solid fuel rock motors also improve their stability and extend their life but working with munitions remains potentially dangerous and must be done correctly every time. Complex weapons such as a Sea Viper round or Spearfish torpedo are bulky, highly sophisticated, expensive and must be handled with extreme care.

The distinctive cruciform-shaped Integrated Weapons Complex (IWC) buildings at DM Gosport. (Image: Google/DigitalGlobe)

For testing complex weapons at each of the DM sites, there is at least one Integrated Weapons Complex (IWC). Laid out in a cruciform shape they have four Weapons Assembly and Check Rooms (WACR) connected to a Test Equipment House (TEH) in the centre. Several weapons at a time can be prepared in each WACR, while tests are performed in sequence from the TEH. The TEH is a reinforced concrete box, structurally separate from the WACR to reduce shock transfer. The WACR has three thick reinforced concrete walls with a lightweight roof designed to send blast upward. The IWCs have sophisticated remote monitoring linked to CCTV, intercoms and fire alarm systems. Energy supplies to the weapons under test can be quickly isolated remotely if an unsafe fault condition is detected, preventing potential detonation. Other facilities such as the Weapon Process Buildings, Ammunition Test Buildings, and Explosives Preparation Rooms are also designed with measures to mitigate the effects of any accidental explosion.

The storage and transport of munitions within the naval bases is minimised and the DM sites are deliberately situated some distance away. The volume of explosives allowed to be stored at each location at any one time is very strictly controlled by licence and the bunkers within each DM site are well separated. The sites have to be well maintained, the grass is kept cut short to minimise the spread of fire and new trees are planted regularly to help reduce blast effects.

DM Gosport and Portsmouth

DM Gosport is a large site and employs approx 270 civilian staff primarily dedicated to RSMI munitions to warships based in Portsmouth. The northern end of the site comprises 26 separate explosives storage bunkers, while the southern section (former RNAD Frater) includes 2 Integrated Weapon Complexes (IWCs) and 24 processing rooms. Gosport deals with naval CW including Sea Viper (Aster), Sea Wolf, Sea Ceptor, and the Sting Ray lightweight torpedo. Staff from the site also maintain a comprehensive ammunition supply and support service for all large (4.5”) and medium calibre guns (20/30mm) and small arms, both ashore and on board ship.

  • DM Gosport. The munitions are taken from the storage bunkers and loaded into barges at the jetty on the left and then towed down Fareham Creek to the Upper Harbour Ammunitioning Facility (UHAF) which can just be seen top right. (Image: Google/DigitalGlobe)

  • DM Gosport is a large facility which covers an area of approximately 470 acres, with a frontage to Portsmouth Harbour of nearly 2.5Km. The explosives storage bunkers can be seen top right and missile laboratories lower left. (Image: Google/DigitalGlobe)

  • HMS Dauntless, one of the first customers to use the UHAF, Portsmouth Harbour, 2013.

  • Sea Viper is lifted onto the UHAF from the lighter in its cradle. The cradle is laid down on the jetty and missile canister lifted out to be lowered into the vertical launch cell aboard HMS Diamond, March 2016.

  • Lighters alongside the Gosport Ammunition Jetty (Photo: Microsoft/BingMaps)

Ships requiring munitions in Portsmouth are usually ‘cold moved’ by tugs to the Upper Harbour Ammunition Facility (UHAF). Lighters bringing the weapons from DM Gosport are towed to the UHAF where they are unloaded by crane for embarking on the warship. The UHAF is a 15 x 85-metre jetty sited in the middle of the harbour to distance it from the naval base and shoreside. The £18M Jetty was completed by VolkerStevin in 2012, along with two mooring dolphins and two small vessel pontoons. It is self-supporting, having its own electrical generators and welfare facilities for the civilian staff from DM Gosport who manage ammunitioning operations. The UHAF was specifically designed to load the large Sea Viper missiles that equip the Type 45 destroyers using its 2 x 34-metre boom cranes (but is also used by other warship types).

DM Plymouth and Devonport

Warships in Devonport are supplied with munitions from DM Plymouth (formerly Royal Naval Armaments Depot Ernesettle). Although within the city of Plymouth the site is inconspicuous and many of its explosive storage bunkers are underground in the adjacent hillside. DM Plymouth covers a smaller area than Gosport and has a single IWC. Munitions can be delivered to DM Plymouth by sea, by road or by rail. DM Plymouth deals with the RSMI of a similar range of munitions to Gosport, apart from Sea Viper. The Ernesettle Jetty is used to take munitions by lighter down to ships moored in the river Tamar. Unlike Portsmouth, there is no ammunition jetty and ships loading or unloading munitions are secured to buoys in the river, just to the north of the Naval Base. Crane barges are moored alongside the ship and used to lift the munitions off the lighters.

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    HMS St Albans takes on munitions in the River Tamar, January 2009. Crane barges lift ammunition from lighters alongside.

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    HMS St Albans receives her outfit of Harpoon missiles (left) while Sea Wolf missiles are lowered into the vertical launch cell (right).

  • HMS Enterprise deammunitioning at bouy in Tamar

    Sailors from HMS Enterprise secure her to the buoy in the river Tamar ready for unloading 20mm ammunition and pyrotechnics, prior to refit, July 2018. (Photo: @HMSEnterprise)

  • Crane barge on the buoy with HMS Enterprise ready to lift ammunition into the lighter alongside, July 2018. (Photo: @HMSEnterprise)

  • RM Plymouth (formerly known as RNAD Ernesettle) with the naval base to the South. The munitions are stored in underground bunkers dug into the hillside at the centre of the image. They are transported out to ships in the river Tamar via the jetty on the right. (Image: Google/DigitalGlobe)

  • The Enesettle ammunition Jetty with two new Serco crane barges alongside.  (Photo: welshwizzard19 Via Flickr)

  • An older photo showing the previous crane barges and ammunition lighters at the Ernesettle Jetty. (Photo: Microsoft/BingMaps)

The Remote Ammunitioning Facility Tamar (RAFT) project began in 2000, to provide Devonport with a dedicated ammunition jetty at Bull Point. Having spent £25M on preparation and dredging 617,000 tonnes of mud out of the river, the MoD cancelled the project in 2004. The primary purpose of RAFT was to allow nuclear submarines to embark Spearfish torpedoes and Tomahawk missiles away from the base. Revised studies assessing the risk showed the remote possibility of a weapon explosion could be safely contained on the existing wharf facilities at the base. The findings of the new study were rather convenient as the original cost of £29M had already spiralled to £45M. From 2020 submarines will no longer be based at Devonport but warships must continue to make do with munitions transfers mid-river, subject to appropriate weather conditions.

Scottish facilities

RNAD Coulport, close to Faslane naval base is primarily concerned with Trident missiles and nuclear warheads (more detail in a previous article here). The missiles are loaded into the submarine at the covered Explosives Handling Jetty but there is a second jetty used for embarking Spearfish and Tomahawks.

Hidden in the hills to the east of Loch Long is DM Glen Douglas, constructed in 1966 and covering 650 acres it employs around 120 people and is the largest weapons storage site in Western Europe. There are 56 storage bunkers built into the hillsides, and a number of weapons processing and engineering workshops. The site serves all three armed forces and has the capacity for almost 40,000 cubic metres of munitions, most of which are transported to the site by rail and sea. A new Road/Rail Transfer Point (RRTP) was completed in September 2016 and Glen Douglas maintains a fleet of lorries that travel up to 400,000 miles a year transporting munitions across the UK. Glen Douglas stores a high volume of bombs, ammunition, explosives and pyrotechnics but does not routinely deal with complex weapons. At Glen Mallen on Loch Long, there is a deepwater Jetty that can accommodate large warships and RFAs where they can load or unload munitions delivered by road from Glen Douglas. The jetty was refurbished in November 2014 and is licenced to handle up to 440 tonnes of munitions at a time.

  • HMS Ramsey at the Glen Mallen Jetty, April 2018 (Photo: J M Briscoe, via Flickr)

  • DM Glen Douglas, the new road/rail transfer point can be seen bottom left while the storage bunkers are dispersed around the hillsides. (Image: Google/DigitalGlobe)

  • RFA Fort George loading ammunition at Crombie Jetty, 2008.

  • The NATO-funded 700-metre deepwater jetty at Crombie can accommodate very large vessels. (Image: Google/DigitalGlobe)

  • DM Beith

    Part of the facilities at DM Beith, in an inland rural location, North Ayrshire. (Image: Google/DigitalGlobe)

  • DM Beith has the contract to store and maintain the Spearfish Torpedo. It is currently working on a complex programme upgrading the whole stock to Mod 1 standard which will not complete until 2024.

  • Spearfish being embarked aboard HMS Talent at Devonport. Note the temporary platform mounted on the casing and the cradle and pulley system used to lower the torpedo through the weapons loading hatch.

DM Crombie on the banks of the river Forth was built as a munitions site for Rosyth Dockyard during World War I. The site covers 200 acres in a narrow 2-mile long strip along the banks of the river and has underground bunkers designed to withstand a direct hit from a 1,000 lb bomb. Crombie has remained open despite the closure of Rosyth Naval Base, although staff numbers have declined to below 100. As well as general naval munitions, it is known to store explosives used for mine warfare and complex weapons for the RAF. A new 700m long jetty was built in 1989 part-funded by NATO and is licensed to handle 110 tonnes of explosives at a time. It has not been publicly confirmed, but the deepwater jetty may allow Crombie to play a role in preparing and loading the air-launched weapons for the QEC aircraft carriers.

DM Beith is an inland munitions depot about 20 miles south west of Glasgow. It was established during World War II and is sprawling site covering 1,000 acres with 21 miles of internal roads, and almost seven miles of perimeter fence. Employing more than 200 staff, the depot’s storage capacity is some 18,000 cubic metres. Its main focus is on the supply of complex weapons for all three services. Beith does not just undertake RSMI of complex weapons but is sub-contracted by BAE Systems and MBDA for assembly and manufacture work on torpedoes and missiles.


Until the dawn of internet mapping and Google Earth many of these sensitive installations were not even allowed to be marked on public maps, a policy abandoned around 2006. Today the easy availability of interactive maps, satellite images has raised awareness of the DM infrastructure. At a time of undiminishing terrorist threat, it is a concern that government has cut MoD Police numbers by 30% since 2010, without a similar sized reduction in the estate they have to guard. Automated surveillance and detection technology are improving but overall there are declining numbers of civil servant employees and fewer security personnel at most of these sites. Patrolling some of these obscure and remote sites, particularly on cold dark nights must be a dull, yet unrelenting and thankless task. The costs of the DM infrastructure are not insignificant. Typically each site has numerous individual buildings and structures, many need heating, lighting (often 24/7) and must be maintained to high standards and comply with modern regulation.

The investment made by a previous generation in first-class munitions facilities has left a great legacy with significant spare capacity in the system. The MoD’s track record of safe weapons handling is generally good and is controlled under a strict, safety-first regime. In wartime conditions, how well the system would cope with a large upsurge in demand is hard to say. Recruiting munitions specialists is a challenge and total civilian staff numbers are much reduced (to around 1,100), even from the period when the UK was involved in the conflicts of the early 2000s.


Main image: HMS Dragon at the UHAF, 2015 (Photo: Creature Stream via Flickr)