KER 11.3 Sail Configuration Guide

Overview

Designed by Jason Ker and built by Vision Yachts, the KER 11.3 is a high-performance racing yacht optimized for competitive IRC fleets. This design targets serious racing teams looking for a fast, responsive platform capable of both windward-leeward and offshore courses.

Rig Specifications & Performance Analysis

• Mainsail Configuration: A P/E ratio of 2.88 indicates a high-aspect rig designed for maximum lift and efficiency when sailing upwind.
• Foretriangle Design: The I/J ratio of 3.54 is optimized for high-aspect, non-overlapping working jibs that provide exceptional pointing ability.
• Sail Area: 76m² total upwind area delivers a high power-to-weight ratio for a vessel of this displacement.
• Performance: The combination of a deep draft and high-aspect rig makes this boat exceptionally weatherly and fast in light-to-moderate air.

Popular Sail Configurations

• Mainsail: Most boats utilize high-roach or square-top configurations to maximize the 15.30m luff length.
• Headsail: Common setups favor a range of non-overlapping jibs (J1 to J3) to maintain efficiency across the wind spectrum.

Key Characteristics

• High-aspect 2.88 P/E ratio for superior aerodynamic efficiency.
• 3.54 I/J ratio designed for high-performance, easy-tacking jibs.
• Deep 2.40m draft provides the necessary stiffness to carry 76m² of upwind sail.
• Responsive hull design suited for technical racing and aggressive sail trimming.

Sailing Considerations

• Requires an active crew of 7-9 to manage righting moment and rig tension.
• Highly sensitive to backstay and jib lead adjustments for optimal slot control.
• Performance expectations include early planing speeds and high pointing angles.

Sailmaking Recommendations

For the KER 11.3, we recommend SurgeX membrane sails as the optimal choice for most sailors. SurgeX uses continuous fiber construction where fibers are laid along load paths and embedded in a thin membrane, providing superior shape retention compared to traditional Dacron while being more affordable than premium laminates. The continuous fiber structure means less stretch over time, maintaining the designed sail shape for years.

For racing applications, specify a lightweight SurgeX configuration with carbon or Technora fibers and minimal base weight to maximize performance. For offshore or dual-purpose use, add a light taffeta protective layer on both sides to enhance UV resistance and abrasion protection. Based on the 2.88 P/E ratio, a load-path-mapped membrane layout works best to handle the high vertical loads of this tall rig. A typical inventory includes a square-top mainsail, a medium-heavy jib, and an A2 asymmetric spinnaker. With 76m² of sail area, plan to reef the mainsail around 20 knots to maintain flat boat trim and rudder grip.

Conclusion

The KER 11.3 is a refined racing machine that rewards precise sail trim and high-modulus materials. Explore sail options for KER 11.3 to unlock its full IRC potential.