Supporting the fleet – Serco services for the Royal Navy

Serco Maritime Services operate the tugs that are commonly seen assisting RN vessels to leave and return to harbour. Serco also provides a diverse range of other marine services, that support warships and submarines. In this article we examine another of the key enablers that the RN could not sail without.

A PFI that works

The RMAS (Royal Maritime Auxiliary Service) which provided waterfront support to the RN was semi-privatised in 1996. The RMAS fleet was in a poor state and a Private Finance Initiative (PFI) offered an opportunity to recapitalise the fleet. In 2007 the RMAS was dissolved and the MoD signed a 15-year, £1bn Private Finance Initiative (PFI) contract with Serco Denholm Marine Services Limited for the Future Provision of Maritime services (FPMS). SD took over the remaining vessels and between 2007-10 invested around £130 Million in 29 new vessels. Serco bought out its partner Denhom in 2007 but the SD prefix for its vessels has been retained. As the fleet was upgraded, there was a turnover of personnel as modern vessels with much-reduced manning requirements and entirely new ways of operating were introduced. By 2015 the service had settled into the new routine and is performing well, 99.9% of taskings have been delivered on time. Private Partnerships with the MoD and across government have had very mixed results and gained a poor reputation. The Army recruitment contract with Capita and the collapse of Carillion are examples of how they can go wrong. A collaborative relationship and an intelligent customer, together with the right initial investment in modern vessels are cited as the reason why this particular partnership is a success. The FPMS contract is due for renewal in 2022 and Serco expect to be in fierce competition with other marine service providers.

Serco Maritime Services is part of the Serco Group that has around 70 contracts for a range of support functions across the MoD. The company now operate a total of 113 vessels in the UK, including a contract with International Nuclear Services (INS) to manage and crew the 4 ships that transport nuclear materials in and out of the UK and across the world. Including the INS vessels, Serco employs around 1,000 seafarers in the UK but it should be noted they are not Sponsored Reservists and there is no provision for the vessels to be deployed in a conflict zone. During the Falklands War ocean-going RMAS tugs deployed in support of the task force but the current fleet of tugs do not have the range and any such requirement would have to be met by ships taken up from trade (STUFT).

  • SD Victoria is described as a “worldwide support ship” and is known to deploy for training and possibly covert operations, carrying military and special forces personnel. She has a large storage hangar, an operations room and several briefing rooms. She has a permanent crew of around 16, accommodation for up to 72 troops. Fast Interceptor Craft (FIC) used by the SBS can be seen under wraps on the working deck in this photo (Photo: Steve Wenham)

  • SD Northern River is the largest ship operated by Serco. Her duties include transport of naval equipment, target towing during naval exercises, noise ranging, data gathering and submarine escort. She is also the primary vessel designated to embark the NATO Submarine Rescue System. (Photo: Steve Wenham)

  • SD Tempest

    SD Tempest was purchased specifically to assist the Queen Elizabeth class aircraft carriers in and out of port. The original plan for the carriers called for two tugs on the head rope but it was realised this would be difficult to execute. Serco invested £8 million in this Advanced Rotor Tug (ART) equipped with two thrusters at the bow and one at the stern, giving an 80-tonne bollard pull. The project was price-neutral for MoD as two smaller vessels have been sold to offset the cost. Portsmouth, Nov 2018

  • SD Forceful and SD Adept pull HMS Sutherland off the wall at South Yard, Devonport, July 2017. Five of these Voith Schneider twin unit tugs, dating from the 1980s, are the main workhorses for assisting vessels based around Devonport.

  • SD Resourceful and SD Dependable assist HMS Ambush to come alongside Valiant Jetty at Faslane, 2014. The hull shape of submarines makes them challenging vessels for tugs to manoeuvre in confined spaces.

  • SD Impetus is one of two 320-ton Azimuth Stern Drive tugs built in 1993 and the largest of the Serco tugs based in Scotland. Escorting the USNS Leroy Grumman into Faslane, October 2016 (Photo: Paul Thallon via Flickr).

  • Serco operates a mix of modern and legacy vessels. Small tractor tug SD Genevieve dates from 1980 and was inherited from the RMAS, while ASD tug SD Suzanne was built in 2010. Portsmouth, Nov 2018.


Serco are responsible for the safe transportation of fuel and ammunition between depots and warships at the 3 naval bases for distribution to the fleet, although the actual handling of munitions is performed by DM staff. To completely outfit a Type 45 destroyer with ammunition is a 3 week activity of planning and execution. It takes about 10 barge loads and 4 days alongside at the UHAF to fully load or unload, a destroyer. There is strict regulation about the volume of ammunition that can be loaded simultaneously. In Portsmouth, there are 3 fuel oil barges with a total capacity of 2,200 tons. They are able to pump about 100 tons per hour into a warship so to fully fuel HMS Queen Elizabeth with her total capacity of 4,800 tonnes of diesel and 3,700 tonnes of aviation fuel is a lengthy process.

Some of the work is distinctly unglamorous but vital to the functioning of the more ‘sexy’ front-line warships. Sullage and tank cleaning barges help decontaminate fuel tanks and remove sewage and grey water. Serco are also responsible for the movement of personnel around harbours as well as providing the transport for Admiralty pilots. During the dredging of Portsmouth harbour to prepare for the arrival of the aircraft carriers, pilot boats conducted 1,600 tasks in support of the contractors, about three times their normal level. Navigation marks and buoys in the naval ports also have to maintained and updated.

As an example, a Type 45 destroyer returning to Portsmouth after a deployment will require two or sometimes three tugs to guide it into the harbour and bring it alongside. It will be cold-moved across to the UHAF to be de-ammunitioned and later taken back to its berth or into a non-tidal basin. Fuel and waste tanks may require cleaning and Serco barges will collect the sullage. As this ship prepares to turn to sea, the process is performed in reverse with the addition of refuelling and the supply of fresh water. In general terms, Serco’s workload will be inversely proportional to that of the fleet. When the harbours are more empty there is less to be done but as the fleet returns for Summer or Christmas leave periods, demand for its services increase.

This is not a ‘pay as you go’ contract. If the RN decides to make occasional additional harbour movements above what has been planned, there is no extra cost to the taxpayer and a service level agreement specifies a flexible arrangement. The requirements of the Navy are the priority but Serco can assist with commercial vessel movements if they have spare capacity and profits from this work are shared with the MoD. The company is always looking at innovation to save costs and draws on best practice from the world of commercial shipping. The majority of their new vessels have been purchased from Dutch shipbuilder, Damen who have specialist expertise in the construction of tugs harbour craft. It is a shame there is no British company able to complete with Damen, but Serco has an established and successful relationship with this supplier.

  • SD Warden based at the Kyle of Lochalsh is used to support QinetiQ and the RN with experimental and trials work. Seen here preparing to recover a USV during exercise Unmanned Warrior, October 2016 (Photo: US Office of Naval Research)

  • SD Cawsand used to transfer personnel to and from warships undergoing Flag Officer Sea Training (FOST) serials around Plymouth. Serco has a special license from the Maritima and Coastguard agency allowing the transfer of people from its tenders to moving vessels. Sept 2013 (Photo: Nick Sidle via Flickr)

  • SD Eva – Fast Personnel Transfer Carrier can carry up to 34 passengers at 22 knots. Note the distinctive axe bow form which was developed and patented by Damen. Greenock, March 2017 (Photo: Paul Thallon via Flickr )

  • SD Clyde Spirit, one of the Admiralty pilot boats used to transfer pilots out to vessels entering harbour (Photo: Damen).

  • Fuel barge SD Ocean Spray towed by SD Indulgent – on her way from Portsmouth Naval Base to fill up from the Gosport Oil and Fuel Jetty. Portsmouth, Aug 2018.

  • Oil and water barges – SD Oilman and SD Waterman alongside at the Serco base in Great Harbour, Greenock on the Clyde, Feb 2016. (Photo: Paul Thallon via Flickr)

  • Essential, but about as unglamorous as marine services get – sullage barges used for the removal of sewage and oily water from ships fuel tanks. Portsmouth, Nov 2018

  • SD Angeline is a multi-cat delivered in 2015 used for towing, mooring, pushing, lifting, recovery and submarine support work. Holy Loch, Feb 2016 (Photo: Paul Thallon via Flickr )

Onboard the SD Indulgent

SD indulgent is a fairly typical modern harbour tug built by Damen in Poland in 2009. She is an Azimuth Stern Drive Tug (ASD) of about 158 tonnes and, together with sister SD Independent, are the workhorses vessel supporting warship movements around Portsmouth harbour. She spends the vast majority of her time at work in her homeport but occasionally makes longer passages to help with naval movements around the UK. She assisted HMS Duncan into Cardiff docks for the NATO summit in 2014 and may be called on to assist with the departure of submarine HMS Audacious from Barrow to begin sea trials in Spring 2019. In normal operation, she has a crew of four who can live in reasonable comfort on board when she is assigned as the duty tug. There are 6 berths on the lower deck, a mess room for up to 12 people, laundry room, showers and a galley below the bridge.

The tug crews in the naval bases work on a rotating duty basis. One of the larger tugs is always assigned as duty vessel for a week at a time. The crew live on board and the diesel engines are kept warm, ready to sail with 10 mins notice. A second tug crew is kept at 2 hrs notice to sail and a third at 8 hrs notice. HMS Queen Elizabeth requires six tugs to leave or enter Portsmouth and this evolution takes considerable forward planning.

  • The tug master’s position on the bridge. Typical of modern tugs with a commanding all-round view, only slightly restricted by the funnel uptakes to port and starboard.

  • The tugmaster sits in the control position with a joystick in each hand. The joysticks are used to rotate the two independent azimuth thruster units. The tug has no rudder and powerful directional control can be exerted by changes in the thruster direction. Depressing the lever on the top of the joystick applies power

  • SD Indulgent heading out of Portsmouth Harbour (Photo: Max Speed via Flickr)

  • The clean and relatively spacious engine room is dominated by the two Caterpillar diesel which supply a total of about 3,480 Bhp to the two thrusters. Indulgent has a bollard pull of around 40 tonnes and has a maximum speed of 13 knots ahead and 11 knots astern.

  • This diesel engine drives a powerful fire pump capable of supplying pressurised seawater for firefighting to the nozzle on the bridge roof.

  • The old practice of towing ships with ropes secured to bollards or hooks has been replaced with synthetic high-breaking strain ropes attached to robust towing winches. The spacious quarterdeck is usually kept clear for towing duties but the knuckle-boom crane can be used to embark up to 25 tonnes of deck cargo.

  • SD Bountiful outboard of SD Independent, seen on departure from ‘Serco City’, Portsmouth. Note the bespoke grey fenders designed to reduce the marking of warship hulls left by traditional black fenders.

Around the bases

SD vessels are mainly employed around the three Naval Bases but there are also Serco facilities at Greenock on the Clyde and Kyle of Lochalsh. Each of the five sites is slightly different in focus. Besides being a frigate and amphibious base, at Devonport, there is a lot of personnel transfer work and harbour movements associated with FOST which provides training to the RN and foreign navies. Serco also supports regular submarine movements at Devonport, although this is rapidly declining. Submarine movements are ideally done with a matched pair of two tugs of the same class on either side of the boat. Moving the large Vanguard class boats through the confined channels is the most critical of these tasks. Devonport also has by far the oldest tug fleet which is due for replacement soon after the FPMS contract is renewed in 2022. There are about 25 Serco vessels based in Scotland, the main work being in support of submarines. Great Harbour in Greenock is primarily a berthing facility for vessels working in the Clyde area. The harbour at Kyle of Lochalsh is a logistics base for vessels that support the work at the nearby British Underwater Test and Evaluation Centre (BUTEC) which is engaged in underwater weapons trials, sonar development and testing vessels noise signatures. Serco also supports the RN in overseas territories and has a small presence in Gibraltar, the Falklands and Cyprus.

The distinctive black and white SD vessels provide a unique and vital service to the RN and are another important part of the little-appreciated infrastructure needed by an effective navy.