Imagine a naval ship that combines the best elements from different technologies. The simplicity, rigidity and ruggedness of a steel hull, which can be built at almost any shipyard, ingeniously integrated with a superstructure with all the attributes of carbon fibre composites. And what if you could also pre-install and verify all the systems, radars and antennas in the superstructure, and then just lift the structure into place on the hull, attach all connections and launch the ship into the sea?
Such a concept is being presented by Saab, where knowledge, technologies and products from different parts of the company are integrated into a complete solution. It is a scalable concept, starting with SLIM, Saab Lightweight Integrated Mast, and extending all the way to composite superstructures with bridges, control rooms, weapons, and all the other equipment and systems needed in a modern ship.
In Karlskrona, Sweden, the department for composite technology has developed a method whereby a carbon fibre superstructure can be pre-built on a stainless steel frame. All the necessary equipment is installed in a controlled environment, and tested and verified. When it’s ready, the structure can be shipped to a shipyard and attached to a steel hull, anywhere in the world. Once it has been lifted on board the ship, the attachment is a simple plug and play process – a process that also reduces the overall construction time and cost.
Ships with improved performance and a reduced profile
A composite superstructure can have many advantages compared to traditional steel constructions. For example, the weight is reduced, which gives increased capacity for pay-loads. Since this reduction applies to the upper parts of the construction, the stability is also significantly increased. With a carbon fibre composite, you also get stealth attributes, such as a reduced radar cross-section and a lower IR signature.
Equipment such as antennas and radars can be installed inside the composite mast, which not only hides them but also protects them from exposure to harsh weather conditions. At the same time, interference between different systems can be minimised and tested, since all installations are performed before mounting onto the ship.
Constructions in composite materials have a very attractive life-cycle cost. Corrosion is non-existent, so is therefore not an issue. In the event that the structure should sustain damage, this is normally limited to the area of impact, making it easy to perform repairs on board. In addition, the sandwich construction also provides very good insulation, protecting against both the heat and the cold, which is perfect for tropical as well as Arctic conditions.
“At Saab Kockums, we have been using different methods to build composite ships since 1974, when the first mine sweeper, HSwMS Viksten was launched. Using non-magnetic materials, such as carbon fibre and plastic resin, makes it possible to design vessels with unique stealth attributes. It also gives significantly lower weight and lower maintenance costs”, says Daniel Oscarsson, Head of Business Unit Surface Ships at Saab Kockums.
The carbon fibre composite technology has been proven and verified in products such as the Visby-class corvettes. This is a series of five vessels, with the first ship being launched in 2000 in Sweden, and which has since gone on to receive recognition far beyond the Baltic Sea.
Recently, ST Marine in Singapore has launched the eighth and final Littoral Mission Vessels, RSS Fearless, for Singapore Navy, where Saab Kockums has contributed with basic design and superstructures in carbon fibre composite.
During recent years, Saab has also delivered carbon fibre superstructures for two Kamorta-class corvettes (P28) to Garden Reach Shipbuilders and Engineers in India.
Industrial cooperation and technology transfer
To most coastal countries, the ability to maintain shipbuilding capacity is of vital importance. This is essential not only for new constructions but also for the performance of maintenance and repairs, and to ensure high availability for the country’s navy.
“Saab and a local partner, can set up a joint industrial project to deliver modern naval ships that benefit from the best of two worlds – local control and ownership, combined with experience and technology from Saab”, says Lars Rönnquist, Head of Saab Singapore and former Head of Marketing for Saab Kockums.
This is a business model used by Saab and its partners in several markets and in various areas, such as for Gripen air fighters in Brazil. Another good example is the project for eight LMV ships in Singapore. In a contract with the main contractor, ST Marine, Saab provided the basic design for the ships, including calculations for performance, and documentation for classification, such as DNV-certification. The shipyard at Saab Kockums in Karlskrona was then awarded the contract to build the superstructures and ship them to Singapore. During this process, staff from Singapore came to Sweden for training and technology transfer, and composite experts from Saab Kockums conducted staff training at the shipyard in Singapore.
The result was that Singapore’s navy received eight modern ships with state-of-the-art technology, ready to patrol the busy waters of the Singapore Strait. But, in addition, the shipbuilding industry in Singapore also increased its competence and capability, ready to offer its services to new markets.