With an Advanced Kit from Diab together with carbon fiber laminates, and support from CCG, Rosattra Boatyard has created an impressively light boat.
Rosattra Boatyard knows what it takes to make a fast sailing boat that is also comfortable enough to use as a second home for summer holidays. When the request came for a fast and easy-to-handle sailing boat, the experienced boat-builders chose to design it using an Advanced Kit from Diab together with carbon fiber laminates, and with support from CCG.
Founded in the 19th century, Rosattra Boatyard is the oldest operating boat-building yard in Sweden. The company offers custom-made sailing boats and is famous for its high-quality Linjett series. The experienced boat-builders are now taking their expertise to the next level with the Shogun 50, a speed demon made of carbon fiber composite materials. To achieve a fast-going yet comfortable sailing yacht, Rosattra Boatyard turned to Diab and CCG for help.
Composites Consulting Group (CCG)
An independent Diab Group company, Composites Consulting Group (CCG) provides specialty composite technology services. From design and engineering to testing, tooling, process optimization and training, CCG helps customers realize the full value of composite designs. The mechanical and process engineers, material scientists, naval architects and composite technicians at CCG have many years of experience from a wide range of industries.
The project: The Shogun 50
A Swedish owner of a Swan 50 wanted a new boat that would better serve his purposes. Due to the size and depth of his boat, he needed a big crew to sail it and could only enter a limited number of guest ports. He wanted an equally tough and fast boat that could be handled by fewer crew members and that featured a nicer interior.
Rosattra boatyard was commissioned to build the new vessel. The experienced boat-builders teamed up with renowned boat designer Håkan Södergren and his son Oscar Södergren, as well as the Vaxholm Komposit company, experts in carbon fiber composite solutions, to create this truly spectacular boat.
The hull of the Shogun 50 does not quite follow the traditional design with a wide and flat stern, common among modern racing sailboats. Instead, it features a slimmer stern and a narrow hull with a keel that can be lifted from 3.5 meters depth to 2 meters, allowing for more flexibility in the choice of harbor. However, the most spectacular thing about the Shogun is the incredibly low weight of 7,800 kg.
To save weight and achieve a perfect fit, from the keel to the mast, the builders decided to go for a full sandwich solution using an Advanced Kit of IPN, together with laminates of carbon fiber. Sandwich panels of IPN core and carbon fiber skins were also used for the interior, allowing for an extremely light boat. The panels were finished with a thin layer of oak veneer to complement the 3 mm thick deck made of teak wood, thus ensuring the look and feel of a luxury yacht. Weight and strength calculations were carried out by CCG engineers.
A kit from Diab consists of pre-cut parts, shaped to suit the design and then numbered to fit exactly into their designated places in the mold. The kit design is based on customer requirements for weight, cost and quality, as well as geometry, manufacturing process and lay-up sequence. With a kit solution, it is possible to boost performance in terms of weight, cost and quality, shorten lay-up time of the core in the mold and improve surface quality and decrease weight. In addition, the amount of waste handling is minimized, and material stocks reduced.
Divinycell HM80 was mainly used in the deck and hull. A high-performance structural core, Divinycell HM was designed for extremely demanding applications, such as fast marine hulls. It combines very high shear strength with an outstanding shear elongation. As a result, it’s an extremely tough product, capable of absorbing high dynamic impacts and slamming loads. Divinycell HM’s elongation exceeds the requirements of ISO 12215, GL and ABS rules, allowing for reduced safety factors in structural calculations while providing for a lighter, yet strong structure. Its high compressive properties offer excellent resistance to denting and skin wrinkling of thin skins. Offering a high operating temperature, it also reduces the risk of prints on dark hulls.
Divinycell H130 was used locally in heavily loaded areas. Providing excellent mechanical properties and low weight, it’s widely used and has a proven track record in virtually every application area where sandwich composites are employed, including marine, transport, wind energy and civil engineering. It’s compatible with most wet resin systems and its low thermal conductivity makes it especially suitable as insulation at low or cryogenic temperatures.
By eliminating the on-site shaping and cutting of flat sheets, the Rosattra boat-builders were able to reduce build times and achieve a perfect fit. “The kit saved us time in production and the result exceeded our expectations on accuracy and quality,” says Daniel Gustafsson, production manager and one of the owners of Rosattra Boatyard. “The injection process went according to previous tests and the quality was very good. The overall efficiency when it comes to time and economy was enhanced through the use of the ready-made kit.” The Advanced Kit decreased the resin uptake in the IPN core, allowing for a light yet strong material, while the calculations made by CCG engineers for weight and strength have ensured that both the hull and the deck of the Shogun 50 are as stiff as required for truly hard sailing. The demanding weight goal for the intended boat racing class has also been achieved.
Name: The Shogun 50
Length over all (LOA): 15.22 m
Length of waterline (LWL): 14.20 m
Width: 3.88 m
Depth: 3.5-2.00 m
Weight: 7,800 kg
Mainsail: 75 sqm
Foresail: 60 sqm
Gennaker: 230 sqm
More info: www.shogunyacht.se