The Design Spiral Helps Lead Teams From Concept to Completion

Experience Across High-Performance Designs

I’ve been involved with many new and exciting designs for years. My focus has been high-performance vessels ranging from 20- to 120-feet, including motor yachts, production boats, patrol craft, and fishing vessels. Early in my career, I developed a passion for designing sportfishing boats, whether smaller outboard-powered craft (these days not necessarily so small) or larger sportfishing yachts up to 105 feet in length.

It’s been my privilege to develop long-lasting relationships with many of the top builders of these vessels. One thing I still find intriguing is how different each project is—and how different the design process can be with each builder. While the designer/builder relationship varies, there are similarities that are almost always present.

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Understanding Builder Needs

Every builder has a unique set of needs. Some have large staffs of engineers, designers, and naval architects, while others have no in-house design team at all. Production builders typically have many resources available internally. Custom builders in the sportfishing world—often cold-molded builders—usually do not.

Even among custom builders, needs and approaches vary. Every new design, whether quantified or not, uses the design spiral approach to some degree.

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The Design Spiral in Practice

The design spiral always starts with mission requirements. This may seem obvious, especially for a sportfishing yacht, but every project has specific goals. Speed, range, power, arrangements, bespoke features—these must all be defined early.

The design spiral allows for iteration during the design process while converging on the ultimate solution. The process can also be customized for each design and build.

As the spiral tightens, levels of detail increase. A concept design may involve just one loop. As the design progresses, additional loops are required—moving from concept design, to preliminary design, to detailed design, and sometimes to full production design. In my experience with custom sportfishing clients, needs typically fall somewhere in the middle of these successive design levels.

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Core Design Deliverables

At a minimum, a builder may require:

• Weight estimating (critical in high-speed hulls)
• Performance and powering estimates
• Hull form development, including propeller tunnels
• Shaftline arrangement, locating engines, gears, shafts, and appendages

Some level of structural design is also normally required, including structural arrangement, material specifications, and laminate schedules. For cold-molded builders, a set of jig frames is required, based on these inputs.

The scope of deliverables may include hull jigs alone or extend to jigs for the deck, deckhouse, flybridge, and even exterior furniture.

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Increasing Design Detail and the Shift to 3D

A more functional or detailed design can include general arrangement (GA), machinery layout, systems design, and countless other elements.

One clear trend over the past five to ten years has been the move toward 3D modeling. Instead of endless 2D drawings, many builders now prefer 3D models that can be used directly for assembly and fabrication. In many cases, a 3D model communicates design intent more clearly than traditional drawings.

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Collaboration Is the Key

Sometimes a full detailed or production design package is required. This demands significantly more time and effort from the design team, and costs can rise quickly depending on the level of detail involved.

A builder’s approach depends heavily on who they have on staff. In some cases, the design and engineering group functions as an external entity. I prefer to think of the design group as part of the builder’s team. This approach makes collaboration easier—and in my view, it’s the only way to do it right.

Every build requires input from many parties: owner, builder, designer, naval architect, suppliers, and vendors. It always takes a village.

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From Concept to Completion THE BOAT DESIGNER/BUILDER RELATIONSHIP

My experience with custom builders varies greatly, and that variety is what keeps these projects exciting. Being involved from the concept phase through sea trials and delivery is both fulfilling and reinforces the team aspect of the process.

I’ve been fortunate to work with world-class sportfishing builders and to develop lasting relationships throughout the industry. With clearly defined goals and open, positive collaboration, a successful design can be achieved.

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By Christopher Swanhart

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