Sub contracting

Ever wondered what life is like below the waves? At the Royal Navy Submarine Museum in Gosport, Portsmouth Harbour you have the chance to find out. A visitor attraction devoted to life undersea, it is home to HMS Alliance, the UK’s only walk-through submarine. From 1 August nautical fans have had an extra reason to visit, with the public opening of the John Fieldhouse building.

The new two-storey extension forms part of a £3.1 million expansion of the museum, which includes the complete renovation of an existing, adjoining building. Named after the most senior submariner in history, Lord John Fieldhouse of Gosport, its primary purpose is to house a World War II X-craft mini-submarine, the HMSX24, which was corroding in its previous outdoor position. It will also include interactive displays and space for temporary exhibitions and events.

In keeping with the museum theme, architect Robert Warren designed the building to resemble a submarine. As well as the overall shape, the interior was given the naval treatment. Southern Electric Contracting (SEC) project manager Peter Crew explains: “The architect had very strong opinions on what he wanted the building to look like, which is basically like the inside of a submarine, so he was looking for an industrial look.

“It’s unusual because normally the architect doesn’t want to see anything on view...this architect’s vision was to see all the services.”

SEC carried out the electrical installation in both new and existing buildings. Its subsidiary, SEC Datacom completed the Category 6 data cabling installation for the exhibition area. SEC won the contract by competitive tender at pre-design stage, working with the consultant to finalise the detailed design.

SEC southern area manager Rodney Sheriff elaborates: “There were a lot of aesthetic design solutions that went into the building once we hit the site. That was through working with the architect and the consultants to come up with solutions that would work functionally and to the architect’s requirements.”

Work began on the site in earnest in November 2004 following the removal of an oil storage bund from the area – the remnants of a formal navy ship petrol station. Some stripping out of the existing building was done while the site was being cleared.

Submarine services

The first job on the new build for SEC was the installation of ground floor conduit and service routes prior to the floor slab being poured. Its early involvement was imperative as the submarine was craned into position immediately afterwards, with a temporary protective covering erected while the building was constructed around it.

The firm then worked in the existing exhibition building until the new structure was watertight, before it recommenced work there. The co-ordination of work and contractors in the new building was slightly unusual, with generally no need for separate first and second fixes. Crew explains: “It was fairly unconventional because there isn’t any plastering. Because there aren’t very many walls in effect, we put all the containment on the mezzanine floor, then surface conduit from there in one fix.”

“Close co-ordination with the architect and the consultant was essential to deliver the solution that was required,” adds Sheriff. No formal partnering agreements were in place but SEC has worked with management contractor Henry Jones on many previous contracts as had the two firm’s project managers, which proved beneficial. Sheriff confirms: “We have existing relationships at management level and site level. We know how to interface with their company, so it gives us some benefits.”

“I think once you’ve worked with somebody you know their requirements, so it does definitely help,” adds Crew. The process was further aided by the formation by Henry Jones of a site office compound in a car park on navy grounds alongside the buildings. All access to the site was from this area as the remainder of the museum complex, which comprises several buildings and displays over a large site, remained open to the public throughout construction.

The electrical services in both buildings are reasonably conventional. Here, the positioning, installation methods and finishes required careful attention to detail to meet the architect’s vision.

The lack of ceiling voids and desire for an industrial feel combined to put the final finishes in the spotlight. “Trunking and cable tray would normally go above the ceiling, so it needs to be mechanically sound and level, but it’s not on show. Because there’s no ceiling in [the new] building it needs to be of a higher quality than usual...you’re looking at the finished product, whereas normally you’d only see the socket or outlet,” stresses Crew. The bulbous wall of the structure was to remain as free from services as possible, which necessitated the majority being distributed via the mezzanine floor.

The heart of the electrical installation is the existing switchroom at the rear of the old building, from which all circuits emanate. The primary supply is from the ringmain feeding the surrounding naval base, which comprises mainly admin and accommodation and includes an escape tower for training submariners.

New distribution boards have been installed to serve the various circuits. From these, cabling feeds underfloor into a single riser at the rear of the John Fieldhouse building and out at floor and mezzanine levels. A circular network of lighting attached to the underside of the mezzanine floor provides lighting for the ground floor and inner walls.

At ground level – the area for corporate hire and temporary exhibitions – floor boxes have been installed in co-ordination with the museum curators and exhibition organisers. When interactive displays are needed they can simply be plugged in without trailing cabling.

Further sockets have been installed on the steel girders supporting the mezzanine floor. SEC apprentice Douglas Orrell (see box) cites this as one of the most challenging parts of the installation. “The architect didn’t want us to use pre-manufactured clips,” he explains, “We had to drill and tap rather than just hammer on a clip.” This meant careful work to ensure the final finish met standards, but also added around 20% onto the installation time for this task – pre-planning was essential to maintain schedules. “It’s all on show so has to look exactly right,” he stresses.

The mezzanine floor houses the family-orientated interactive displays. These are fed via floor void services.

In the existing building, m&e services were completely stripped out and replaced. The historical artefacts displayed here previously are being returned, albeit rehoused in more modern display cabinets. Most are irreplaceable, a fact that the m&e services had to account for. “Light is the issue in the museum space,” explains museum spokesperson Brian Seeney, “hence there are no windows and the [m&e] system is designed to take lighting types into account – daylight is what kills artefacts.”

A ceiling-suspended track lighting system has been installed on a grid layout in this area. This will give flexibility for future changes to the displays; the lamps can simply be removed from the track and repositioned where needed. To maintain the architectural design here a specially manufactured black trunking was used, again meaning pre-planning was essential as a three to four week delivery time was needed for the product.

The official opening of the building by HRH the Princess Royal is scheduled for 8 September. And with up to 80 000 visitors a year, if you want to beat the crowds and experience a depth charge, now is the time to set sail.