Hydraulic refit helps boost ferry capacity

Bosch Rexroth has supplied hydraulic lifting cylinders and associated control systems for new high level linkspan bridges at Southampton and East Cowes on the Isle of Wight.

Bosch Rexroth has supplied, installed and commissioned hydraulic lifting cylinders, variable displacement power units and associated control systems for new high level linkspan bridges at Southampton and East Cowes on the Isle of Wight.

The client, Red Funnel Group, commissioned the work through main contractor Dean and Dyball Construction, as part of a GBP 10 million investment in the ferry company's Southampton to East Cowes route, which was triggered by significant traffic growth in recent years.

Red Funnel, the original Isle of Wight ferry operator, has extended and refurbished two of its three modern 2900 tonne, Raptor class vessels, Red Osprey and Red Falcon, stretching each boat and adding an additional full-length car deck, to provide the capacity for another 80 or so vehicles.

The provision of another deck necessitated an additional roll-on/roll-off linkspan level at both ports, as well as the refurbishing of existing hydraulics lifting equipment.

Rexroth, whose UK Hydraulics in Civil Engineering team specialises in the installation and upgrade of ro-ro linkspan and walkway facilities, completed the work on schedule with minimum disruption to ferry sailings, in line with Red Funnel's policy of not inconveniencing its customers.

The scope of supply included three new 160mm bore, 5.5m stroke hydraulic cylinders for the Southampton end, including a spare; two new 280mm, 5.1m stroke units for East Cowes; the refurbishment and refit of three existing cylinders; two hydraulic power packs featuring tandem fixed displacement pumps; and associated control systems, complete with automatic linkspan levelling facilities.

Originally formed in 1861 by a merger between two competing Solent ferry operators, the Red Funnel Group is a modern and highly successful transport company based in Southampton, whose activities include ro-ro and high-speed catamaran ferry operations, ferry-inclusive holidays and short breaks, nationwide distribution and freight services.

The famous red funnel and black top was first adopted across the entire fleet in 1935, giving rise to the Red Funnel name and today's distinctive brand identity.

The group actively promotes the brand through advertising, events and sponsorship and was one of lone yachtswoman Ellen MacArthur's first personal sponsors, as well as supporting Olympic gold medallist Shirley Robertson.

Red Funnel's cross-Solent ferries carry in excess of 2.6 million passengers and 0.6 million vehicles annually, the majority on its ro-ro service between Southampton and East Cowes, and last year the group announced substantial traffic growth, outperforming an already buoyant market for Isle of Wight travel.

To meet this increased demand, it launched a long-term investment programme, including the launch of a new Red Jet 4 high-speed catamaran and the refit of its roll-on/roll-off passenger/vehicle ferries.

Red Osprey, one of Red Funnel's three state-of-the-art ro-ro ferries, sailed to Gdansk in Poland, in September 2003, to undergo stretch and refurbishment work, a replacement vessel operating in its place to maintain the normal timetable.

This extensive conversion, since applied to the second of three sister ships, Red Eagle, involved the removal of the complete passenger lounge, promenade area and wheel house, the separation of the hull and insertion of a new mid-body section, and the building of a full-length car deck, resulting in extra capacity for around 80 cars and an additional lane for heavy goods vehicles.

The third vessel, Red Eagle, will be stretched in 2005.

The extra car deck clearly required revised ro-ro vehicle handling facilities and Red Funnel simultaneously commissioned the Ringwood southern region office of Dean and Dyball, one of the largest privately owned construction groups in the UK, to build new high level linkspans at both terminals, including access ramps, hydraulic lifting equipment and infrastructure.

Thanks to its technical expertise in this area and competitive tender, Rexroth was chosen to design and install the hydraulics systems.

At both ports, it needed to accommodate the extra loads imposed and the considerable vertical movement of the linkspan ramps, dictated by the high Solent tides.

At East Cowes, the original linkspan was operated by two hydraulic cylinders mounted on an overhead gantry, with a purpose-built machinery room and operator kiosk located alongside.

The additional linkspan, designed to connect with the new upper car decks, is now mounted over the original, with a concrete bankseat constructed as an abutment for the linkspan hinge and a fixed cradle on the original linkspan to support the front end.

The effect of this revised design was to increase the load on the cylinders, so Rexroth was required to increase the capacity of the hydraulic system and install a new control panel, without disrupting ferry operations.

Four cylinders, two each side, now support the two-tier linkspan, which are operated by two power units housed in an enlarged machinery room.

In addition to refurbishing and refitting the existing equipment.

Rexroth supplied two 280mm bore, 125mm rod, 5.1m stroke hydraulic cylinders, installed a new hydraulic power pack and connected all four cylinders to the tandem power units, in a revised configuration.

Rexroth additionally incorporated an existing diesel-powered generator into the system, to provide emergency standby power, and linked together three hydraulic fluid reservoirs with a large balance line, complete with separate isolators.

The operator's kiosk has been relocated to the moving linkspan, for optimum view of both decks, and a new control system installed, including main panel, cylinder load transducers and an auto levelling function that synchronises the raising/lowering speed of all cylinders.

The original linkspan at the Southampton terminal was a floating design, with buoyancy adjusted to suit the ferry height, which was considered inappropriate for the revised ro-ro arrangement.

So Rexroth collaborated with Dean and Dyball on the design and construction of a new hydraulically-operated 30m linkspan, incorporating a fixed ramp to gain height to the elevated ferry deck, a bankseat and linkspan hinge, and a forward gantry for supporting the cylinders.

The concrete ramp also provides space beneath for the machine room and hydraulic power unit.

Two 160mm bore, 80mm rod and 5.5m stroke cylinders support the new Southampton linkspan and are mounted rod upwards, since the hydraulic lines are routed along the linkspan deck.

Control of the hydraulic system, again incorporating auto levelling, is achieved by radio transmitters or handheld pendants connected directly to the deck.

The linkspan is additionally designed to "float" with the ferry deck, as the vessel's buoyancy changes according to the tide, and it enters this mode once lowered into position; although if physical contact with the ferry is lost or sudden movement detected, the control system locks and holds the linkspan in a failsafe position.

Work was completed over a scheduled three-month period, with both ports remaining open throughout, other than a 2200-0500h overnight shutdown on just two days.

The system has been successfully commissioned and is being operated as normal by Red Funnel.

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