Serco Denholm will be supported by The Briggs Group, who will provide buoys and mooring support from their base in Burntisland on the Firth of Forth as work transfers from HM Mooring Depot at Pembroke Dock. The company are responsible for their own plant.

SDMS formally signed their contract with MOD in December 2007 but work to identify the floating plant required to carry out the work and procure suitable new vessels started in 2003. Ownership of the majority of the existing MOD marine services fleet has been transferred to SDMS by MOD but it was recognised by Serco from the outset that a considerable fleet replacement programme would be required. At that early stage it was necessary to identify the floating plant needed to support precisely the needs of the Royal Navy, while taking into account the numbers and types of new warships, (surface ships and submarines), coming into service in the foreseeable future. A package of over 30 vessels of many different types was subsequently identified to replace some existing plant and to reconfigure the fleet to meet those demands.

The Damen Shipyards Group, based at Gorinchem in the Netherlands, was approached to develop a 29 vessel package valued at €146m. The Damen package comprises vessels of 15 different designs, including pilot boats, tugs, barges, multipurpose work vessels, a fast crew boat and a worldwide support ship. Within that total number are 16 tugs and tug/workboats, some selected from Damen’s standard range and others modified or purpose designed. Three distinct Damen project areas are involved and eleven production centres within the Group, with the Tugs & Workboats project office taking the lead for a large share of the work.

In the latter stages of the project the selected shipbuilder Damen was enabled to commence design and construction with a view to completing the new build package by 2010. A direct benefit of this approach and planning was the delivery of the first vessel of the order, the small tug/workboat ‘SD Catherine’ to Portsmouth in early January and a sister vessel, the ‘SD Emily’, due in March for deployment on the Clyde.

SD Catherine and SD Emily represent a small but significant milestone for the project, enabling many of the principles and procedures developed for the introduction of new vessels, including equipment, training and deployment, to be put to the test. These first vessels are standard Pushycat 1204 workboats, powered by a single Caterpillar 3056 TA diesel driving a single screw. A propulsion nozzle is fitted, and twin rudders to give a 2.1 tons bollard pull and good handling qualities. In keeping with virtually all similar tugs and work vessels on order, they are equipped with ‘grey’ fendering to minimise damage to warship paintwork and most will have fendering beneath the waterline to enable them to be used in close contact with submarines.

The traditional black hull and ochre livery carried both by the Serco Denholm and Royal Maritime Auxiliary Service (RMAS) support craft throughout the history of the service will be retained throughout the fleet. Again, in keeping with RMAS tradition, it is likely that most of the smaller classes of tug will be given female names.

A total of eight vessels will be delivered in 2008, the remainder being six Damen Stan Tender fast pilot and VIP passenger boats destined for use in Portsmouth, Devonport and the Clyde. Two sizes are under construction, three Stan Tender 1505 and three of the larger Stan Tender 1905 design. All six will be capable of 20 knots and there will be maximum commonality in construction, equipment and operation. One boat of each size will be deployed at the ports mentioned, with the larger vessels also intended for carrying VIPs. All three boats will have a maximum capacity of 10 pilots plus two crew, with the exception of Clyde vessels, which will have a larger crew and different passenger configuration due to local operating conditions.

The majority of the tugs and other specialised craft will arrive in 2009 and 2010.

One of the advantages offered by the Damen Shipyards Group for this diverse range of vessels is that  although several Damen yards and project departments are involved, a common approach and standard of workmanship and a high level of component commonality can be achieved. An indication of the complexity of the project and the effort being expended to achieve the required result was a presentation and meeting held at Damen’s Goringchem headquarters to enable Serco Denholm to meet face to face the technical staff from all of the project areas. Over 80 people were involved.

The tugs on order comprise an interesting mix of twin screw and azimuthing stern drive (ASD) vessels ranging in size from 12m to 26m. Most have been selected from Damen’s standard product range and will be fitted out to the owner’s specification, but two classes will be purpose built, the ASD Tug 2009 and the ATD 2909.

In addition to the two Pushycat 1204 vessels already mentioned, there is one twin screw Stan Tug 1404, a larger and more powerful tug/workboat due for delivery early in 2009.

In order of size, the next design chosen is a new vessel introduced for this contract, the ASD Tug 2009, derived from the successful ASD 2411 shiphandling tug. Of similar hull form and configuration, this 21.19m tug will have a 9.43m beam and draft of 3.6m. A pair of Caterpillar 3508B TA-HD main engines will generate a total of 2,000 bhp to power Rolls Royce US155 propulsion units with controllable pitch propellers. Described as a harbour and coastal tug, the vessel will have a bollard pull of 23.4 tons and maximum speed of 11 knots.

Winches fore and aft will make this vessel suitable for handling the smaller vessels of the surface flotilla, barge work and will also assist with submarine movements. A bow thruster will be fitted and sufficient deck space will be available to transport stores and containers. In common with most of the tugs in the package, a passenger carrying requirement is included, in this case for 12 persons. Four ASD 2009 tugs will be delivered in 2010.

Two larger ASD tugs of the established ASD Tug 2509 design, of 25.89m in length, have also been ordered. The specification includes Caterpillar 3512B TA-HD main engines producing a total of 3,480 bhp to power the same type of Rolls Royce propulsion units as their smaller sisters. A 40 ton bollard pull and 13 knots free running speed is anticipated and the vessels inherent agility will be enhanced further with a bow thruster.

Again, the level of equipment and facilities will far exceed that normally installed in a commercial tug of this type. Two double drum towing winches will be fitted, along with extensive underwater fendering, fire fighting equipment and facilities for passenger and stores transportation. These ‘multipurpose’ tugs will be used for harbour and coastal towing and the deployment and recovery of towed array sonar systems. Delivery is expected in October and November of 2009.

Another established tug design on the Serco Denholm shopping list is the increasingly popular and versatile Stan Tug 2608, a conventional twin screw tug that has emerged as a very effective vessel for coastal and port operations. The tug has a length of 26.61m, beam of 8.8m, a draft of 3,40m and a particularly spacious after deck. Caterpillar 3508B TA diesels, rated at 2,200 bhp (total) will give a bollard pull of 30 tons and maximum speed of 12 knots.

For naval service the tug will have a comprehensive outfit of equipment to equip it for a wide variety of tasks, in addition to towage operations in port and at sea, in much the same way as the ASD 2509. A double drum towing winch and deck crane will be fitted, as well as a versatile communications and navigational installation. The after deck is particularly suitable for the deployment of towed sonar arrays and, if necessary, an accommodation module can be carried to increase the number of personnel that can be carried from 12 to 30. Three such vessels will be completed between January and June 2009.

The largest and perhaps most interesting purchase is a batch of four purpose designed azimuthing tractor drive (ATD) tugs designated the Damen ATD Tug 2909. These 29.19m vessels, with a 9.98m beam, will have Caterpillar 3512B TA-HD+ main engines producing a total of 4,023 bhp coupled to Rolls Royce US205CP propulsion units with controllable pitch propellers located beneath the bow. With a bollard pull of 40 tons, and speed of 12 knots, these vessels will be used to handle aircraft carriers and other large vessels due to come into service. The tugs will have a relatively shallow draft (for tractor tugs) of 4.80m and incorporate extensive fendering above and below the waterline.

All four ATD 2909 tugs will be delivered during 2010. These vessels will replace or supplement existing classes of large berthing tugs. Some of the existing twin Voith tractor tugs, the ASD tugs of the ‘Imp’ class and the recently purchased twin screw vessel ‘Atlas’ will be retained.

Among the remaining work vessels in the Serco Denholm package are two vessels based on the commercial Damen Multi Cat 2510 but equipped for two different purposes, one being mooring and buoy handling and the other being trials support. Both vessels will have standard production pontoon style hulls of 26.27m in length with a beam of 10.64m and draft of 2.55m. Two Caterpillar C18 diesels will power each vessel, with a total of 957 bhp driving a twin screw/fixed nozzle propulsion system. This arrangement will give a bollard pull of 12.5 tons and speed of 8 knots.

The mooring and buoy handling variant will have a single marine crane capable of lifting up to 9 tonnes at an out reach of 7m and be equipped to carry out dive support duties. These vessels will be equipped in much the same way as the tugs previously described with respect to personnel accommodation, transportation, pumping and other peripheral duties.

The trials support version of the multi Cat 2510 will be extensively fitted out, with two cranes to carry out torpedo recovery, towed sonar array deployment and recovery, diving training and many other duties. The hull will be fendered above and below the waterline and the engines flexibly mounted to reduce noise and vibration. Extensive accommodation will be provided for trials staff and the vessel will be fitted with a comprehensive outfit of navigational and communications equipment.

Delivery of the mooring and buoy handling variant is expected in July of 2009 and the trials support vessel in May 2010.

An important feature of the Serco Denholm marine services contract is the transportation and distribution of stores, fuel, water and virtually all the commodities required by a modern warship. In order to streamline the distribution of liquids in particular, three modern (non-propelled) tank barges, each a specialised vessel in its own right, form part of the newbuild package. A 29m Damen Water Lighter Barge 2909 will have a maximum capacity of 272 tons of potable water. The barge will be equipped with two generator sets to power the onboard systems, including two high capacity transfer pumps. A deck crane will handle the transfer hoses and a dedicated gangway. A very similar barge with a carrying capacity of 300 tons, designated a Diesel Lighter Barge 3009, will have almost identical equipment and be used to deliver diesel fuel. The third and more complex barge is a Damen Liquid Mixed Lighter Barge 4315. This 43.22m barge will have dedicated tanks for 424 tons of diesel fuel, 212 tons of Avcat aviation fuel, 424 tons of compensating water and 212 tons of sullage. High rate transfer pumps rated at 100 m3 /hr will be provided for each commodity. The diesel lighter will be delivered in November 2009 and the remaining barges in 2010.

The remaining two vessels in the Serco Denholm order are very interesting indeed and much could be written about them, but a brief outline must suffice until a later date.

A Damen Fast Crew Supplier 3307 is a highly developed crew transport vessel embodying the unique ‘Sea Axe bow’ designed to afford good seakeeping qualities in all weathers. In this naval role, the vessel will be used to transfer submarine crews and training personnel to and from vessels offshore in conditions of up to sea state 4. The all aluminium boat will be 33.21m long, with a beam of 7.4m and depth of 3.3m Two Caterpillar C32-C diesels will run at between 2,100 and 2,300 rpm to give the vessel a maximum speed of 22 knots. Provision will be made for a crew of four and up to 34 passenger, all in individual seats. To ensure that personnel transfer between vessels is as safe as possible, the craft will be equipped with a special fendering system and a swivelling gangway operated by a hydraulic crane with heave compensation. The FCS 3307 will operate out of the Clyde and completion is expected in August 200, when it will replace the existing tender ‘Adamant’.

The largest and most sophisticated vessel in the newbuild package is described as a ‘Worldwide Support Ship 8316’. The 83m vessel is intended to meet an MOD Special Operational Requirement for a ship capable of worldwide operation to carry out training operations with military personnel, transport military personnel and equipment, and conduct diving support operations. Among the extensive facilities embodied in this design are classrooms, briefing and operations rooms, workshops, extensive storage areas of various kinds, a helicopter winching deck, and provision to carry and operate Rigid Inflatable Boats. The ship will have a twin screw diesel propulsion system to give a speed of over 14 knots and an endurance of 30 days. This complex and sophisticated vessel will be built to SOLAS standards at Damen Shipyard Galatz and completion is scheduled for May of 2010.

In addition to the Damen package, SDMS have ordered two Henderson International design 50.9m multi-role support vessels, which are under construction by the Abu Dhabi based company ADYard. These are twin screw vessels based on a small, shallow draft, anchor handler design incorporating a large clear after deck, winches and deck crane.

As previously described, the Briggs Group will work closely with Serco Denholm as sub-contractors to take joint responsibility for delivering moorings and navigational buoys services. Looking to the future, Briggs has placed its own orders with Damen Shipyards. One of the newbuild vessels will be allocated to provide support to the contract. Ordered separately at a cost of €14m is a Damen anchor handling supply vessel 6114 to be equipped for buoy and anchor handling and general towage duties. To be named the ‘Kingdom of Fife’, the 61m vessel will have a bollard pull of 68 tons and maximum speed of 13 knots. Delivery is expected in the spring of this year, when a full description of this impressive vessel will appear in Maritime Journal.

Also ordered, to their own account, Briggs has under construction the ‘Forth Jouster’ a Damen Multi Cat 2612 triple screw work vessel equipped for a wide range of anchor handling and marine operations. Due for delivery in August 2008, the vessel will have a bollard pull of 33 tons and maximum speed of 10.5 knots.