| Industry | Marine Services |
|---|---|
| Predecessor | Royal Maritime Auxiliary Service |
| Headquarters | |
| Parent | Serco Group |
| Website | www.sercomarine.com |
 |
| His Majesty's Naval Service of theBritish Armed Forces |
|---|
| Components |
|
| History and future |
| Operations |
| Equipment |
| Personnel |
| Auxiliary services |
Serco Marine Services is aPrivate Finance Initiative contract, withSerco Group, to deliver auxiliary services toHis Majesty's Naval Service (incl.Royal Navy,Royal Marines andRoyal Fleet Auxiliary).
Marine Services primarily operates from the nation's three main naval bases,HMNB Portsmouth,HMNB Devonport andHMNB Clyde, but also supports training and operations overseas, as well as at variousBritish Overseas Territories.
Serco Denholm (a joint venture between Serco Group andDenholm Group)[1] won the Marine Services contract, replacing the subsequently disbandedRoyal Maritime Auxiliary Service. Denholm's participation was bought out in late 2009 by its larger partner, Serco.[2] In 2025, Serco won a renewal of the contract to continue services for the Naval Service until 2035.[3]
In 1976, the formerAdmiralty Yard Craft Service merged with the Royal Maritime Auxiliary Service to provide Marine Services for the United Kingdoms Naval Service. However, by 1996 Marine Services was put out to commercial tender by the Ministry of DefenceWarship Support Agency (now part of theDefence Equipment and Support organisation) which resulted in all tugs, lifting craft and various tenders being operated by Serco Denholm (the joint venture between Serco Group and Denholm Group).[4] The commercial tender awarded to Serco Denholm also included the management of naval bases Devonport, Portsmouth and Clyde.[4] At the time of theInternational Festival of the Sea in 2005, Serco Denholm were operating over 120 vessels in support of the Naval Service, including tugs, passenger vessels, pilot boats and a range of stores and tank-cleaning lighters.[4] Although Serco Denholm operated and provided all auxiliaries, it did so under the then Royal Maritime Auxiliary Service.
In 2006, the MoD awarded the "Future Provision of Marine Services" contract (aPrivate Finance Initiative) to the preferred bidders, Serco Denholm.[5] In December 2007, Serco began the flagship £1bn Private Finance Initiative to provide marine services to the Royal Navy for the next 15 years. This contract includes the manning, operation and maintenance of over one hundred vessels and the introduction of around thirty new ones.[6] As a direct result of this, the Royal Maritime Auxiliary Service which had previously provided this role was formally disbanded on 31 March 2008.[7] All vessels formally prefixed RMAS assumed the SDprefix instead.
In 2009, Serco (being the larger partner in the joint venture with Denholm) bought out Denholm's share. Since then, all vessels have seen the SD funnel logos replaced with the Serco logo on the vessels superstructure. However the SD prefix has been retained. The service is now known as Serco Marine Services.[2]
Serco Marine Services supports the Naval Service and theRoyal Fleet Auxiliary (RFA) in both port and deep water operations.[8] In port and UK waters, Marine Services is primarily tasked with berthing and towage activities located at the three main naval bases; Devonport, Portsmouth and Clyde. Other tasks such as coastal logistics (including stores, liquids and munitions) and passenger ferrying is also readily undertaken. Out-of-port operations in UK waters include direct involvement in supporting diving and minelaying training exercises, as well as torpedo recovery.[2]
Serco Marine Services may undertake similar activities at British naval facilities overseas, which includes the maintenance of navigational marks (or buoys) and supporting military operations and training.[2]
As part of the 2025 renewal contract, Serco is to acquire 24 new vessels as part of a modernization to fleet and replace older tugs and service craft. A further five-year contract involves the provision of inshore support for military training, including services and diver training (delivered in partnership with Briggs Marine) at the British Underwater Test and Evaluation Centre (BUTEC) in Scotland. Serco is also to deliver offshore support for military exercises, both in the U.K. and globally.[9][10]
As of 2025, Marine Services operates more than 90 vessels at six locations in the U.K.[11] at:Portsmouth,Devonport,Falmouth,Clyde and two atInner Raasay Sound. The Marine Services were also said to maintain a presence in certain overseas territories, includingGibraltar, theFalkland Islands and theBritish Sovereign Base Areas in Cyprus.[12][13][14] However, marine services at thePort of Gibraltar are provided by the Boluda Towage Europe[15][16][17] and as of 2021, marine services in the Falkland Islands were provided by the contracted Netherlands Marine Services companyVan Wijngaarden.[18]
Since the disbandment of the Royal Maritime Auxiliary Service, all vessels carry theship prefixSD, and continue to do so since Denholm's share was bought out by Serco in late 2009. Vessels currently in service can be recognised by their black hulls with white beading and white-coloured upperworks. The former buff-coloured upperworks which had once been associated with the RMAS are steadily disappearing with the last few vessels due to adopt the new colour scheme in coming years.[2] Marine Services enablesRoyal Navy and Royal Fleet Auxiliary ships, including the United Kingdom's Strategic Nuclear Deterrent, to either move in or out of port for operational deployment and training exercises around the world. The service operates a large assortment of auxiliaries including tugs and pilot boats as well as transporting stores, liquid and munitions and providing passenger transfer services to and from ships for officers and crew.
All Ministry of Defence-nonowned ships of Serco Marine Services fly theRed Ensign.[2] TheGovernment Service Blue Ensign is worn since 2008 by the many ex-RMAS craft under the management of Serco Denholm which are Ministry of Defence-owned vessels.[19]
The largest ship currently in service isSDNorthern River.[2] In 2025, Serco signed a contract withDamen Shipyards Group for the delivery of 24 vessels of various types as part of a renewal of its fleet. The vessels will include: Azimuth Stern Drive (ASD) tugs, Reversed Stern Drive (RSD) tugs, pilot boats, barges and crane barges. The vessels are to be delivered in 2027 and 2028.[20]
