North Design Suite

As the pioneer of modern computer assisted design (CAD) for sailmaking, North Sails developed the North Design Suite™ (NDS), the most powerful and diverse sail design tools in the industry. A family of 14 specialized software modules, NDS delivers unprecedented power and flexibility to sail design and rig/hull analysis. Each module can interface with any other module in the Suite, making it possible for North sail designers and engineers to virtually sail test a boat in an infinite variety of conditions before the boat is even built. NDS significantly expands a designer’s ability to compare different sail and rig combinations and accurately measure results. Equally important, NDS significantly reduces tuning and development time after launch.

Meet the Suite…


Creates a three-dimensional model of boat and rig

North designers initiate the sail design process using Desman, the skeleton of the North Design Suite. Mast dimensions, rig geometry and attachment points, trimming locations and sail dimensions are specified for a particular boat. The system then incorporates the mechanical properties of rig and sails (moments of inertia, surface area, materials stiffness and sail modulus).

Later in the process, the Membrain  module will use Desman data to determine deformation of sails under load, as well as every piece of standing and running rigging—right down to stretch in sheets and halyards.


Places sails on the Desman model

Spiral allows the designer to apply a specific three-dimensional sail design (mold) to the Desman framework. The sail’s three-dimensional shape is initially defined as a ‘molded’ membrane, without any wind pressure or load applied. Every dimension of the sail can be precisely adjusted both in horizontal and vertical axes, allowing Spiral to apply mainsails, genoas, jibs and asymmetric spinnaker designs.


Defines the structure of the sail

This is where the designer defines the material composition of the sail. For upwind and downwind paneled sails, sailcloth or laminate requirements are determined and individual panel profiles are generated. For 3D molded composite sails, tape layouts and densities are determined and applied in the same three-dimensional space they will assume when sailing.


Applies wind pressure to sail surface and calculates forces created

Using Flow, the designer introduces wind pressure to the sails created with Spiral and Warps. The pressure will vary across each sail’s surface based on the design of the sail and the strength and direction of the airflow. Flow also reports the drive and moments developed by sails, which can later be used by the North Sails VPP (or other VPPs) for sail performance analysis.


Balances wind pressure, sail shape and rig forces

Membrain uses the pressure fields provided by Flow to deform the rig/sail combination as a single unified structure. As the sail/rig structure is deformed, the shape of the sail changes, so Membrain sends the changes back to Flow to acquire updated pressure fields for the deformed surface. This changes the sail shape in Membrain yet again, so the process is repeated until a stable balance is achieved between pressure and rig/sail deformation.

By adjusting variables in sail design and rig, the designer can use Membrain to refine and optimize sail shapes, mast design, rig tune and more.

Virtual Wind Tunnel™ (VWT)

Models air flow on upwind and downwind sails

VWT allows the sail designer to visualize and analyze sail shape, sail forces, shape stability and ease of trim in the computer at 100% scale. It is the first wind flow simulator to model both upwind and downwind sails, and because VWT can work with sail and rig data from a specific boat, it delivers unprecedented accuracy. Originally developed jointly by the Dartmouth College Thayer School of Engineering and North Sails, VWT is now managed by the Stevens Institute of Technology.

VWT is uniquely able to integrate with Membrain, allowing both upwind and downwind sail shapes to be optimized over a virtually unlimited variety of wind and sea states.

North VPP™ and Hull VPP

Integrates rig, sail, hull and appendage performance data

North VPP and Hull VPP are powerful tools that allow sail, rig, hull and appendage data to be effectively integrated, giving sail and yacht designers the ability to analyze an entire sailboat — from masthead to the tip of the keel — as a unified working system.

First, sail and rig data for a specific boat is generated by Flow, Membrain and VWT. Separately, Hull VPP generates hydrodynamic data for the same boat’s hull and appendages. Both sets of data are then fed into North VPP. For particularly demanding analysis, North’s Das Boot is used as a more powerful alternative to Hull VPP.

As a result of this integration, sail refinements can be tailored to a specific boat’s characteristics and also optimized for targeted sailing conditions. North VPP and Hull VPP represent a significant leap forward for North sail designers, allowing them to customize and refine sails for virtually any boat with unprecedented precision.

Race Model™

Measures effects of sail and rig adjustments on rating and vice versa

Race Model allows North designers to make specific adjustments to sail, rig and stability factors — both upwind and downwind — and predict their effect on a boat’s rating under virtually any rule. The process can also be worked in reverse to determine what adjustments are required to achieve a specific rating target.


Quickly compares performance between different sail designs and trims

Sail Performance Prediction (SPP) allows North designers to quickly compare the performance of a new sail design relative to a baseline design. This allows them to test up to ten times the number of shapes within a given time frame (compared to running individual designs through Flow and then coupling these results into the VPP). Additionally, the SPP can derive hull performance data from a boat’s rating when there is insufficient hull data to run the North VPP.


Creates sail crossover charts in a user-friendly format

A good Sail Selection Chart is like an owner’s manual for your sail inventory. For coastal or offshore races, it is critical to have the next sail ready to hoist on the next leg or if sailing conditions change. Sailect clearly presents the optimum ranges of True Wind Speed and Angle for individual sails, allowing them to be used in their “sweet spot” at all times. Choosing correctly when changing sails also minimizes the number of sail changes.

SailScan II™

Compares actual sail shapes to the original design

SailScan II compares photographs of sail shapes taken while underway to the original design file created by Membrain. It is a valuable tool for determining if a sail needs shape adjustments. It also aids North sail engineers and production specialists in refining materials and production methods to improve the competitive life of our sails.


Uses historical weather data over a specific race course to predict sail performance

Router takes a boat’s polar performance predictions, combines them with a historical or predicted weather file for a specified race course, and then “sails” the boat from start to finish on each leg. Comparisons can be made between different sail combinations, allowing North designers to predict the fastest sails for a specific race leg. Router was initially developed by North mathematician Michael Richelson for the winning Illbruck Volvo Ocean Race Team in 2001-02.