Sail Design Process

Three dimensional modeling, pressure distribution, stress strain pictorials, laser cutting, wind tunnel testing, and much more all figure into making a modern sail for your boat. The following outline will bring you through some of the steps used in designing sails in the 90’s and beyond.

The first step in any sail design process is to decide on the geometry of the sail needed to fit the boat. All the outside dimensions need to be defined. In most cases this is an easy operation and can be accomplished by directly measuring the boat with a tape measure or consulting a sail plan which is a scale drawing of the boat. Once the size of the sail is confirmed the interesting analysis starts.

The outside dimensions of the sail are entered into a sail design program where a 3 dimensional shape is described. In most cases 3-dimensional shapes are described by horizontal and vertical cross sections of the surface. The key factors in describing these sections are chord depth %, maximum draft position, entry and exit angle, and twist ( the amount of deflection the leech has from a straight line between the clew and head, generally described in degrees). For most boats the optimal sail shape cannot be applied to the sails because of several obstacles like genoa track locations, spreader lengths and position, headstay sag and mast bend.

For example, if a sailmaker designs a genoa for a boat that has long spreaders and does not consider the spreader length when designing the sail it can not achieve the designed 3-dimensional sail shape the genoa must be trimmed through the top spreader to do so. Since the spreader cannot move the sail cannot be trimmed in, and thus the sail sets with more twist than designed. This one little design flaw causes the sail to set with the following problems, flatter camber than designed, fuller entry to the sail in the upper portion thus, the sail luffs earlier and, wider exit angle decreases the power in the sail.

Once the 3-dimensional sail shape is described the sail is ready for wind tunnel testing. The goal of wind tunnel testing is to optimize the lift and drag ratios for the boat. These coefficients change with the change in 3-dimensional shape. Therefore several models may be made to hone in on exact specifications.

Doyle Sailmakers operate with a central design team. This team consists of highly qualified sailors who each bring different strengths to the team. Richard Bouzaid as the leading designer within the group leads the innovation and research for the Doyle Design team. The design tools are amongst the most advanced 3D modeling and airflow.

Doyle sails are engineered by experienced sailors with a world of know-how. The designs, loads and requirements are calculated on our in-house analysis and CAD programs. What makes Doyle Sailmakers standout from the competition is experience and practical knowledge that can only come from specialists in each specific area.

Specifics such as projected wind range, crossover charts and specifics of an individual sail can be modeled and predicted prior to the sail even being fitted to the boat – making the racing and cruising inventories more than just an estimation or guess at best as most sailmakers have done previously. The design team has the resources of all members of the Doyle group, which encompasses over 70 sailmaking operations.
Doyle Design Solutions
Design Engineering

Our engineers created uniquely effective construction methods, sail handling systems, battens, batten systems, head, tack and clew attachments. Doyle solutions are highly engineered and elegant.
Doyle 3D Imaging Sail Design

Recognizing each sailboat has its particular set of unique characteristics. Doyle sail designers draw on a worldwide pool of veteran sail designers and design information, exclusive Doyle fabrics, proprietary sail design software, and wind tunnel testing. This creates sails which are strong, durable and hold their shape across the wind range.

The sail designers at Doyle, lead by Richard Bouzaid, utilize the world leading sail design software “SailPack”, which has the ability to 3 dimensionally model any sail at the actual flying shape onboard the boat, combined with various sail combinations and settings.