Babcock looks at one of the UK’s most complex defence programmes

07:40 GMT, March 16, 2010 After many years in gestation, the UK’s new aircraft carrier programme – a highly complex engineering, logistical and project management undertaking – is coming to life, as the manufacturing programme gains momentum. In the following Babcock International, part of the integrated industry/UK MoD alliance, the Aircraft Carrier Alliance, responsible for the design and build of the Queen Elizabeth (QE) Class aircraft carriers, provides an insight to defpro.com readers into the programme and the company’s contribution, from preparations to ongoing work and the progress being made.

As preparations are being made for the imminent shipment of the first Lower Block from Babcock’s Appledore shipyard in Devon to Rosyth (marking a significant milestone and start of the assembly and integration process), and with work having recently begun on a section of the hull at Portsmouth (the fifth UK shipyard to start construction on the programme), work on this national project is now underway at sites across the country, with blocks under construction and many of the systems and machinery items in production.

At 65,000 tonnes, 280 metres long, 74 metres wide and 56 metres high, the two vessels will be the UK’s largest warships, each with a flight deck area of around 4 acres (1.6 hectares) from which to project airpower anywhere in the world. Inevitably, the scale of the operation and technical and logistical complexity of the delivery programme for these vital joint military assets is equally huge.


Infrastructure preparations

At Babcock’s Rosyth dockyard, where final assembly and integration of the massive Queen Elizabeth Class aircraft carriers is to take place, a significant programme of civil engineering works is in-hand, to allow entry of the blocks from the various dockyards where they are being built, assembly in No.1 Dock, and then departure of the completed vessels. Works to modify the dock itself began in March 2008.

“Modifications to No.1 Dock have now been successfully completed within the planned timescale and budget,” Babcock Warships Managing Director Mike Pettigrew comments. “This has included cutting back the huge granite steps (known as ‘altars’) along the sides of the dock to adapt its conventional V-shaped profile to a U-shape, and widening the gated entrance.”

Following the construction of a massive five cell, 50,000 tonne cofferdam (a temporary structure to create a dry work environment), the dock was de-watered in October 2008, and work was then undertaken to remove the intermediate caisson cills and jambs; install 165 rock anchors through the dock walls; build the new propped gate cills and jambs; demolish the original entrance to the dock and construct a new, wider, entrance; and reconstruct the foundations for the new gate. With the removal of the ‘altar steps’ the dock floor is some nine metres wider.

Two intermediate gate positions, recessed into the walls, have been located to suit the build strategy for the carriers, and the modified floating caisson gate has been installed. The primary skidding system, used to support and move the blocks in the dock once the water has been removed, has also been constructed. This carries the upper docking and skidding system comprising tools, jacks and rams required to support and manoeuvre the sections of the vessel to a high degree of accuracy during assembly.

Work to modify the direct entrance is still on-going. Rosyth has the largest non-tidal basin for ship repair in the UK, separated from the Firth of Forth by an existing sliding gate entrance to hold the water back. This is being widened by four metres to over 42 metres, and the substantial engineering project that this entails is due to be completed later this year.

Additionally, rails for the gigantic Goliath crane have also been installed, and the crane itself will arrive at Rosyth this autumn. “After four months to erect, test and commission it, the crane will be operational by early 2011,” Babcock Project Director Sean Donaldson reports. “At a height of 68 metres to the underside of the main beams, and with a span of 120 metres to cover the construction area of the new carriers, the Goliath crane will be largest in the UK. Its 1,000 tonne lifting capacity is provided by three hooks, which provides a valuable degree of flexibility. The crane will lift and place the carrier modules, including the upper blocks and sponsons, as well as the bow block, islands and aircraft lifts.”


Design and build

The design and build of the carriers is managed by the Aircraft Carrier Alliance (ACA); an integrated industry/MoD alliance comprising Babcock, BAE Systems, Thales UK and the UK MoD (acting as both partner and client), which is responsible for delivering the ships to time and cost. In addition to the modular build strategy involving construction at different locations, the design is being carried out at a number of different sites using 3D modelling, bringing its own challenges.

Two different CAD tools have been used; Tribon on the forward sections and Foran on the remainder. Babcock’s role includes almost 50% of the CAD-based modelling design and development work on the vessels and, as the assembly site for the carriers, its Rosyth-based engineering design team receives data in both CAD formats. Having one of the largest pools of marine design expertise in Europe, and familiarity with different CAD formats has been an important factor, according to Babcock Integrated Technology Director Ian Lindsay.

“Discussions with the software vendors has led to the successful procurement and integration of both systems allied to the associated hardware, allowing the whole ship to be modelled seamlessly (in itself a project involving hundreds of thousands of man-hours) to ensure that all the separately manufactured elements work together,” he says. “Massive servers are needed to hold all the information, to which all the high spec workstations needed are linked, requiring a high speed of communication for considerable quantities of data. Investment in integrating the software has been backed with parallel infrastructure investment, centralised offices and training programmes.”


Drawing board to reality

As the project moves from modelling to manufacture, construction of various blocks and component parts is now underway at five of the six UK shipyards involved (at Glasgow, Rosyth, Newcastle, Devon, Portsmouth) and is due to begin at Birkenhead in summer 2010, in addition to nearly 100 further contracts throughout the supply chain. The blocks include four Lower Blocks, five upper Central Blocks, 12 sponson units, and two island superstructures, each of which will be transported by sea to Babcock’s Rosyth dockyard for assembly and integration. The project has been aptly described as a gigantic 3D jigsaw puzzle.

Already initial component units for the first carrier sponsons have begun arriving at Rosyth. The first shipment, from Babcock’s Appledore yard in Devon, arrived last August, comprising 11 fabricated units and two flat packs for the first of the sponson blocks, each unit measuring around 10 metres long by 7.5 metres wide and three metres high, and weighing 20 to 36 tonnes. The 12 different sponson units for each carrier form part of the ship structure to provide a wider flight deck.

This was the first of some 20 shipments from Appledore to Rosyth for each of the two vessels, including the 12 sponson units, two shipments for the Lower Block 1 sub blocks, and four shipments for centre block units. For the first carrier these are taking place at various intervals from August last year to early 2012.

Each of the shipments received at Rosyth will allow work to start on combining the 20-40 tonne individual units into 300 tonne blocks. Major outfit can then commence on electrical cabling and equipments, mechanical pipe systems and equipments, ventilation ducts and equipments, furniture and propulsion, weapon or aviation systems. This will lead to completion of the approximately 1500 different compartments and numerous systems, prior to whole ship assembly.

Shipment of Lower Block 1 will be taking place by barge in the coming weeks. Manufacture of this block at Appledore has included the huge ‘bulbous bow’; a protruding ‘bulb’ at the bow of the ship just below the waterline which alters the water flow around the hull to reduce drag, increasing the carrier’s speed, fuel efficiency and stability. Similar in size and appearance to a conventional submarine, manufactured by joining massive steel plates to produce the complex curvature required, this component alone measures a substantial 27 metres long and 9.5 metres maximum height, and weighs some 315 tonnes, giving a good indication of the enormity of the vessel.

“The assembly and integration stage will involve the use of our heavy lifting, alignment, and fabrication skills,” Pettigrew points out. “As block build progresses, two 500 tonne transporters (delivered to Rosyth last year) as well as the Goliath crane, will play a major part.”


System advances

Meanwhile, many of the various components and machinery have been manufactured or are under construction, such as the diesel generators and turbines, aircraft lifts and steering gear, and progress is also being made on a number of the vessels’ systems. Among these, the highly mechanised weapons handling system (HMWHS) , and integrated waste management system (IWMS), both designed and being built by Babcock, are two examples.

Here again, strong progress is being seen, with component delivery milestones recently announced. The first component of the HMWHS, a pair of hydraulically operated magazine doors each measuring 12 metres wide by 3 metres high and weighing 6000kg, were delivered to schedule for integration at the end of last year. “These will be fitted within the deep magazine complex and are designed to operate automatically as part of the HMWHS,” Babcock Integrated Technology director Matt Hatson explains. “Delivery of the doors was required at this early stage in the build programme as their size and location within the ship means that the doors are an integral component of the vessel. The door insert is welded into the bulkhead of the ship.”

The HMWHS provides mechanical handling facilities for moving palletised munitions around the deep magazine and weapon preparation areas, and a series of weapons lifts connect the magazines, hangar, weapon preparation area and flight deck. This innovative solution to munitions handling represents the first maritime application of shore-based commercial warehousing processes using automated systems with all-electric control, adapted for safe transport and stowage of munitions in a warship environment. The system equates to more than 300 linear metres of handling and storage equipment, with multiple stowage locations for high levels of flexibility and redundancy, and plays a critical role in meeting enhanced operational capability requirements. It is estimated to yield a 65% reduction in manpower required for what is traditionally a labour-intensive, time-consuming and potentially hazardous process, thereby helping to reduce through-life costs and adopt increased safety standards.

Similarly, the first major component of the IWMS, the waste water treatment plant, was also delivered at the end of 2009 by Babcock, ready for installation. The QE Class aircraft carriers are to have the first fully integrated waste management system in a warship, which addresses the collection, transfer, treatment, stowage and disembarkation of the various fluid and solid waste streams generated onboard the carriers, and will process these until the outputs are benign and compatible with International Maritime Organisation (IMO) requirements for overboard discharge, or enabling them to be stored efficiently until landed.

Fluid shipboard waste includes, black water (sewage), grey water (from showers, washbasins, galleys and laundries), and bilge water (oily water waste accumulating in the bottom of the hull), while solid waste products include clinical waste, sanitary waste, food waste, paper, glass, metals and plastics. The IWMS integrates these waste streams and final treatment into a coherent system operating through the ship’s Integrated Platform Management System. It will minimise the manpower requirement and remove some of the current labour associated with waste handling, as well as freeing up valuable on-board storage space, and minimising reliance on shore side facilities. The system will also ensure that increasingly stringent environmental and marine pollution control requirements are met.

“Systems such as these, along with the construction of the vessels themselves and the multiple components that involves, are seeing years of combined design, effort, and integration, starting to come to fruition, thanks to close working between the Aircraft Carrier Alliance partners and throughout the national supply chain,” Pettigrew remarks. “As Defence Secretary Bob Ainsworth commented recently, the progress already being made to deliver these assets which will be a cornerstone of future defence policy is a testament to the skill and professionalism of UK industry.”

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