The Westerly Cirrus 22 Sailboat
Specs & Key Performance Indicators

Published Specification for the Westerly Cirrus

Keel & Rudder Configuration: Fin keel & spade rudder
Hull Material: Fibreglass (GRP)
Length Overall: 22'0" (6.7 meters)*
Waterline Length: 19'0" (5.8 meters)*
Beam: 8'0" (2.4 meters)*
Draft: 3'6" (1.1 meters)*
Rig Type: Sloop
Displacement: 3,240 pounds (1,470 kilograms)*
Ballast: 1,455 pounds (660 kilograms)*
Sail Area: 233ft² (21.6m²)*
Fuel Tank Capacity: 7 gallons (26.5 liters)
Hull Speed: 5.8 knots 
Designer: John A. Butler
Builder: Westerly Marine Ltd
Year First Built: 1968
Year Last Built: 1972
Number Built: 398

* Used to derive the design ratios referred to later in this article - here's how they're calculated...

Published Design Ratios
The Key Performance Indicators (KPIs)

• Sail Area/Displacement Ratio (SA/D): 17.1 - This indicates that the Cirrus has a moderate sail plan relative to its displacement. It suggests a balance between power and ease of handling. This ratio implies that the Cirrus should perform well in a variety of wind conditions, providing decent speed while still being manageable for cruising.

• Ballast/Displacement Ratio (B/D): 44.9% - A higher B/D ratio like this one indicates good stability and stiffness. The Cirrus should be relatively stable, making it a reliable and steady performer. The substantial ballast helps the boat resist heeling and enhances its ability to right itself.

• Displacement/Length Ratio (D/L): 211 - This ratio is a measure of the boat's weight relative to its length. A ratio around this number typically suggests a moderate displacement boat, which balances comfort and performance. The Cirrus should have enough displacement to provide a comfortable ride without being overly sluggish.

• Comfort Ratio: 15.8 - This ratio gives an idea of the sailboat's motion in a seaway. A comfort ratio in this range indicates that the Cirrus is designed for a relatively smooth ride. 

• Capsize Screening Formula (CSF): 2.2 - This ratio assesses the likelihood of the boat capsizing. A CSF below 2.0 is generally considered safe for offshore sailing. At 2.2, the Cirrus is at the upper end of what's considered suitable for offshore use, suggesting it's better suited to coastal and inshore waters.

Overall, the Westerly Cirrus sailboat should offer a balanced sailing experience with good stability, decent performance, and reasonable comfort, making it well-suited for coastal cruising and general recreational sailing.

But the Design Ratios are Not the Whole Story...

Although the design ratios can be interpreted to provide an indication of such a vessel's likely sailing characteristics they do however, have their limitations:

• The design ratios are static measurements which don't account for dynamic factors like wave action, wind gusts, or crew actions.

• They simplify complex interactions into single numbers, which can be misleading. Real-world performance is influenced by a multitude of factors that these ratios can't fully capture.

• The context in which the boat is intended to be used (e.g., coastal cruising vs. offshore racing) can greatly affect how these ratios should be interpreted.

Consequently, while these ratios provide valuable insights into the theoretical performance characteristics of a sailboat, they should be used as part of a broader assessment that includes practical experience, sea trials, and expert advice.

More Specs & Key Performance Indicators for Popular Cruising Boats

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