SOUTHERLY 145 Sail Configuration Guide

Overview

The Southerly 145 is a high-performance bluewater cruiser designed by Richard Carter and built by Northshore for serious offshore passage-making. With only three boats in existence, this design prioritizes stability and long-range comfort for experienced cruising couples.

Rig Specifications & Performance Analysis

• Mainsail Configuration: A P/E ratio of 2.57 indicates a moderate aspect rig, balancing aerodynamic efficiency with a manageable center of effort.
• Foretriangle Design: The I/J ratio of 2.59 is optimized for versatile headsail setups, comfortably supporting both high-overlap genoas and working jibs.
• Sail Area: 82m² total upwind area provides significant power-to-weight for a vessel of this displacement.
• Performance: The sail plan is engineered for predictable offshore handling and steady cruising speeds rather than aggressive technical racing.

Popular Sail Configurations

• Mainsail: Most owners opt for fully battened configurations to maintain leach profile and simplify reefing.
• Headsail: Large furling genoas are standard, often supplemented by a removable inner forestay for heavy-weather staysails.

Key Characteristics

• Moderate P/E ratio ensures the rig remains manageable for shorthanded crews in heavy weather.
• Balanced I/J ratio allows for effective light-air performance with overlapping headsails.
• Deep 2.40m draft creates a stiff, weatherly platform that tracks well upwind.
• 82m² sail plan provides a versatile power range for varying sea states.

Sailing Considerations

• Recommended for 18-20 knot reefing intervals to maintain optimal heel angles.
• Typical crew requirements are 2-4 people for comfortable offshore handling.
• Expect a stiff, stable ride with minimal tender behavior in gusts due to the deep draft.

Sailmaking Recommendations

For the SOUTHERLY 145, 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 minimal base weight to maximize performance. For cruising or bluewater sailing, add a taffeta protective layer on both sides to enhance UV resistance and abrasion protection. Based on the 2.57 P/E ratio, a tri-radial fiber layout works best to handle the vertical loads of this moderate-aspect rig. A typical inventory includes a fully battened mainsail and a 135% furling genoa. With 82m² of sail area, plan to reef around 18 knots to keep the boat balanced and minimize weather helm.

Conclusion

The SOUTHERLY 145 is a robust, well-proportioned cruiser that rewards high-quality sail shapes with exceptional stability. Explore sail options for SOUTHERLY 145 to maximize your offshore potential.