Design News for Mechanical and Design Engineers

Today, thanks to a surge in demand for luxury megayachts, a five-year delay to cover the design-to-delivery cycle doesn’t cut it. That’s why a number of high-end yacht builders are transforming the way they engineer vessels, leveraging 3D CAD tools and high-end Computer Numerical Control machines to create a more production-style environment. With these new engineering practices in place, high-end yachts are now sailing off the line in a scant 18 months or less, even with a moderate degree of customization, and quality has improved as boat builders are able to repeat their complex designs on a more consistent basis.

Prior to 3D CAD models, 2-D drawings and human craftsmanship commandeered high-end yacht design. Designers created the complex shapes for the boat — everything from the hull to the interior cabinetry — in 2D drawings. Next, highly skilled loftsman and other craftsman would leverage their years of boat-building expertise to “fill in the gaps” and make the appropriate modifications that would make the 2D drawings spring to life as an intricate boat design. The problem was design elements often got lost in the translation and there was no guarantee the same design would actually yield an identical boat when orchestrated by different loftsman.

“The loftsman at the boat yard would have to reconstruct all the information in such a way that they could build the boat,” says Scott Davidson, product manager at Robert McNeel & Assoc., the Seattle-based maker of the Rhino freeform 3D modeling software used extensively by yacht makers. “In that translation, however, information is lost putting limits on what you can do. You’re limited in how you build things, you’re limited in terms of what shapes you can do and you limit the repeatability of the project.”

A 3D Blueprint

The combination of 3D modelers like Rhino and sophisticated CNC machinery is rapidly altering the boat-building landscape. Instead of one-off, custom designs that are individually hand-cut and built-to-order on the shop floor, 3D models provide a mathematically accurate blueprint for the base model of the boat, which is fed to large-scale CNC machines that cut each component with a high-degree of precision. Yacht manufacturers can then add customer-specified options and preferences to the base model assembly just prior to delivery instead of building each individual vessel to specification from scratch. As a result, the 3D CAD/CAM-driven approach has bolstered design consistency for yacht makers and paved the way for a production-style environment that shortens lead times and boosts their ability to produce multiple vessels.

That’s certainly the case at Westport Shipyard, the second largest manufacturer of composite motoryachts in the U.S., with models ranging from 98 to 164 ft. In 2003, Westport shelved its 2-D CAD tools for SolidWorks' 3D CAD software as part of its strategy to move to a production environment. 2-D design methods were limited in that they demanded a parallel design architecture and there were often interferences when integrating additional systems, which required a great deal of rework in the field, according to Jack Sanford, Westport’s application engineer. “2D comes up short when you’re delivering to the shop floor exactly what you want to build so there’s lots of room for interpretation,” Sanford says. “There was always something left out of the equation so you’d have to get on the boat and decide how to custom fit pieces and trim. It’s simple to do that when you’re building a house where everything is linear and rectangular, but with a boat, everything has shape.”

Westport embarked on its 3D journey with the development of its 164-ft luxury model, which has more than 30,000 components in the boat structure alone and would require over 250,000 to 300,000 man-hours to build. The original intent was to design all of the interior woodwork in SolidWorks — cabinetry, the walls, the ceiling and anything else that was constructed of wood in the boat after the fiberglass frame — the goal being to more efficiently reproduce the boat over and over again while reducing the amount of man hours for production.

With its older 2D-based processes, Westport’s first production boat was a prototype, but also a deliverable. Armed with incomplete 2D data, Westport crew members would physically have to adjust designs to fit, which meant there could be different interpretations from crew to crew and boat to boat. Moreover, on a boat this size, design changes occur dynamically depending on which system crew is up first. For instance, the electrical team is impacted by where the plumbing team puts in their systems and vice versa. “With a partial amount of information, everyone was scrambling to refit around who was there first so there were constant modifications that deterred repeatability,” Sanford says. “The next boat was built differently and so on and so on.”

That’s not the case with a 3D model, which has robust large assembly capabilities, allowing Westport designers to resolve fit and interference issues prior to production. The software, coupled with CNC automation for all cabinetry, interior joinery and other select systems, has enabled Westport to reduce its customer delivery times by 75 percent, down to 18 months from five years. It’s also reduced production time and decreased Westport’s reliance on skilled labor.

SolidWorks’ eDrawings 3D viewer has also helped Westport improve quality and reduce errors. The boat maker’s cabinet shop uses eDrawings files and the tool’s redlining capability to communicate details and changes amongst the internal team and with suppliers. In addition, interior designers tap eDrawings to help clients more fully visualize rooms, including materials selections and finish options, as opposed to providing a limited look with 2D drawings.

Moving forward, Sanford expects Westport to broaden the role of 3D as the platform for building all systems, including the fuel tanks. While some of these systems are currently built in other design tools, Sanborn says Westport will eventually move to a single CAD system to eliminate much of the conversion efforts that regularly occur.

While the move to 3D has increased the amount of design time, Sanford says the payoff is tenfold, particularly at the production floor level. “We’ve got hundreds of people now assembling, not trying to decide what they need to do,” he says. “It’s improved our design and reduced the amount of time to get things done. We know exactly what we’re building every time.”

Sabre Yachts, a maker of high-end, Down East-style powerboats and sailboats, has also embraced 3D CAD in its quest for design repeatability. The company employs Solid Edge from Siemens PLM Software for its interior joinery along with Rhino and the MultiSurf 3D surface modeler for boat components that require more curvature and shape. As a production-style boat maker, Sabre makes a base boat, which can then be customized with options based on customers’ requirements. While the options were possible with a 2D design approach, 3D tools like Solid Edge make the process faster and more repeatable, according to Paul Naughton, product engineer for the South Casco, ME, company.

“We put out a standard set of specifications, but what we can excel at with 3D is making changes quicker and faster to accommodate customers,” he says. Sabre also spends less time building something once and then building it again. “Now we put forethought into the design so the option has less impact on the production line than it did before.”

It’s a similar story at The Hinckley Co., another production-style boat maker, which builds between 60 to 80 boats on an annual basis. While there is a base Hinckley design for each model, a good 10 percent of a boat is custom tailored to individual customer’s preference so repeatability, even with options, is critical. “Anything from the engine package to a custom rail to electrically actuated transom steps can be specified,” says Burr Shaw, Hinckley’s engineering director. “If it’s at all possible to accommodate a customer’s request, we’re going to do so. We don’t say no to anything.”

Using Solid Edge, Hinckley is able to produce those one-off options in a much shorter period, Shaw says. In addition, 3D models and CNC machinery enable the company to create a boat’s interior on the production floor as prefab assemblies as opposed to building the cabinetry and joinery in the boat like it used to do. “Now things can only go together one way,” Shaw says. “All the mounting surfaces are molded in, critical dimensions are controlled and variability is limited, not to mention, it’s more obvious if something goes wrong.”

Likewise, the software has helped Hinckley optimize interior configurations on boats, making more effective use of limited cabin space on its 29- to 55-ft models to accommodate components like fuel tanks, machinery and additional cabinetry below deck. Prior to using Solid Edge, Hinckley engineers would design for the unknown, leaving clearances to accommodate possible interferences with parts and assemblies. While that approach addressed some of the limitations of 2D, it didn’t do much to help Hinckley engineers maximize interior space. “With a highly accurate model and tooling, we don’t need to design for adjustability,” Shaw says. “We’re able to more closely dial in our tolerances so not only can we be more efficient in assembly, our designers are a lot finer — hatches and lids work together more smoothly and we fit more into the same space.”

Case in point: Hinckley’s new T38R Convertible boat, which features a new hydraulic, stainless-steel convertible top, which folds away with the push of a button much like a convertible car top. Shaw maintains such a design wouldn’t have been possible with the limited information served up by 2D CAD packages. “The tolerances are very tight,” he says. “The top is over 500 pounds and it changes shape as it moves. It had to be done in 3D to get the tolerances just so.”

In the end, it’s the transition to 3D and all that comes with it that’s playing a key role in high-end yacht makers’ transition to a production environment. “That’s the magic with Hinckley,” says Rick Loring, president of LMGi, a value-added reseller and consulting company that worked with Sabre and Hinckley on their Solid Edge implementations. “You can’t get to higher production with the same level of craftsmanship without doing something like this.”

		Sabre’s popular 34-foot Express model
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