After four years in production at Mconaghy Boats in Zhuhai China, the 42.5 m Adastra trimaran from naval architecture design firm John Shuttleworth Yacht Designs (JSYD) has been launched into the Pearl River in Southern China (also known as the Guangdong River and Canton River as part of an extensive river system in southern China).
Adastra was rolled into the water on a large steel trolley that ran in a track on a slipway. The trolley had to be custom built and required some complex structural design in and of itself.
Many initial, but basic tests were performed in the river to check the engine loading, fuel consumption, and speed curves. According to Shuttleworth, the seakeeping, a measure of how well-suited a watercraft is to conditions when underway, was monitored as well as the maneuverability with the outrigger engines.
“She has been exceeding our expectations with regards to speed and efficiency,” Shuttleworth reports. “It appears from the first measurements taken by the engine manufacturers on the sea trials, that the fuel consumption at 10.5 knots was as low as 29 liters per hour at a payload of 20 tons, (fuel, water, and people).”
The top speed even came in 8% higher than predicted. Initial estimates had Adastra topping out at nearly 26 miles per hour (22.5 knots) with a maximum range of 4,000 miles (when cruising at 17 knots).
The build went smoothly, but keeping the vessel on weight, as well as some other unforeseen challenges, forced the designers to make a few sacrifices along the way.
Keeping the weight of the vessel to a minimum was a priority throughout the entire design process. According to Orion Shuttleworth, one of Adastras design team, that meant several features which he had hoped to incorporate were not included in the final design, including a sliding sunroof in the bimini over the aft deck (the guest area closest to the back of the boat on the main level) and “pirate proof” automatic step covers on the wings that would’ve increased security.
More Photos of the Launch: Adastra Super Yacht Launches in Pearl River
Another interesting feature that didn’t make the final design was the articulating outriggers. “During the preliminary design stage, we built a tank test and remote-controlled model of the boat with outriggers that articulated up and down,” says Shuttleworth. “The idea was that one could lift the outriggers out of the water while at sea so they would be skimming the water, thus reducing drag, and then submerge them while at anchor or port to reduce the roll and make the vessel more comfortable.” In the end, JSYD decided that the additional weight required to build the articulating mechanism would increase the drag more than the potential energy savings from lifting the outriggers out of the water.
Instead, Shuttleworth opted for a fixed outrigger height that offered a compromise between efficiency and stability, and the idea wasn’t developed any further. In the first year of research and development, the company performed extensive tank tests and radio-controlled models tests. For example, the staff recorded a two-meter Adastra model on waves to analyze her stability and performance at sea.
Shuttleworth worked closely with the staff at McConaghy Boats from the moment the builders were selected to the launch and commissioning of the vessel. Over the last two years of the build, Shuttleworth flew to China and visited the yard every 12 weeks to ensure that JSYD’s designs were being constructed according to plan. During each visit, the partners would discuss and develop ideas before holding a design review meeting with the interior designers, the owner, and other relevant subcontractors. Inge Strompf-Jepsen of Hong Kong-based Jepsen Designs is credited with Adastra’s luxurious interior design.
Both John Shuttleworth and Richard Oliver of ASTA also paid regular visits to check on the structural elements of the vessel, and everyone regularly communicated via Skype and email as well. Oliver was charged with carrying out the preliminary Finite Element Analysis (FEA) of Adastra’s structure. The FEA model was put together and meshed in Femap, an advanced engineering simulation software program from Siemens PLM, which creates FEA models of complex engineering products and systems, and displays solution results.
Pain in the Glass
According to Shuttleworth, the windows turned out to be the biggest manufacturing challenge. “Both the saloon and pilot house windows have a large amount of double curvature, which is part of what makes the boat look so futuristic,” he says. “We always knew these would be difficult to build, but the team agreed that we should give it our best shot as [the windows] would look fantastic and be a defining feature of the design.”
The hunt was on for a manufacturer who could produce the windows, but it proved challenging as most companies felt it was beyond their capability. In the end, McConaghy Boats found an Italian company that manufactures windows for a wide range of uses, including Lamborghini motor cars. After several attempts, the company finally managed to achieve the desired result and the last windows were delivered days before the launch.
Adastra’s owners, who played a large role in the development of the vessel, were very pleased not only with the windows, but with the yacht’s entire design. The owners offered constant direction and design input throughout the project.
Staying on Weight
The trimaran came in exactly on the designed weight, an outstanding achievement for the builders. Monitoring the weight played a huge role in the project, as the vessel is incredibly weight sensitive. About 18 months prior to the launch, JSYD and McConaghy Boats made the decision to place load cells under the hull so that the weight could be continuously monitored. “This gave us a good idea of the center of gravity, so we were confident that she would float correctly,” Shuttleworth adds.
JSYD also designed fuel tanks to run along the length of the boat. This allows the owners to use the fuel to trim the vessel in order to optimize fuel consumption and speed. The resulting added tank capacity means that Adastra can also carry a larger-than-usual fuel load a long distance trip without refueling.
JSYD and the companies involved in the design and development of Adastra were recently awarded the title of "Most Innovative Company" at the China (Shanghai) Boat Show. The unique nature of the design was recognized by a panel of judges drawn from local and international media and marine industry professionals.
Shuttleworth had a few jitters when Adastra made her first splash, but those quickly subsided. “There were inevitably a few nerves when she actually went in the water,” he recalls. “Fortunately all went well, and she floated as expected.”
(David Mantey first reported on Adastra in "Super Yacht Prepares to Set Sail," Issue 7, September 2011)