The Irwin 54 Sailboat
Specs & Key Performance Indicators

Published Specification for the Irwin 54

Underwater Configuration: Stub keel with centreboard and semi-balanced rudder

Hull Material: GRP (Fibreglass)

Length Overall: 54'0" (16.5m)

Waterline Length: 44'0" (13.4m)

Beam: 15'4" (4.7m)

Draft: 5'6" (1.7m)

Rig Type: Cutter (as shown in pic, but also produced as a staysail ketch)

Displacement: 46,000lb (20,865kg)

Designer: Ted Irwin

Builder: Irwin Yachts (USA)

Year First Built: 1988

Published Design Ratios for the Irwin 54

1. Sail Area/Displacement Ratio: 15.7

2. Ballast/Displacement Ratio: 34.8

3. Displacement/Length Ratio: 241

4. Comfort Ratio: 39.9

5. Capsize Screening Formula: 1.7

read more about these Key Performance Indicators...

Summary Analysis of the Design Ratios for the Irwin 54

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The Irwin 54 is a 54.0ft staysail ketch designed by Ted Irwin and built in fiberglass by Irwin Yachts. Based on the design ratios, the theoretical sailing characteristics of the Irwin 54 are:

• Sail Area/Displacement Ratio (15.7): This ratio is effectively the Power-to-Weight Ratio and gives an indication of a boat's performance capability. A ratio of 15.7 suggests that the Irwin 54 is slightly underpowered, which might limit its speed potential under certain conditions.
• Ballast/Displacement Ratio (34.8): This ratio indicates the stability of the boat. A ratio of 34.8 suggests that the Irwin 54 is reasonably stable and stiff, and has a good righting capability if knocked down. However, this ratio doesn't take into account the location of the boat's ballast, which can be misleading. A boat with the ballast in a shallow draft keel will be less stiff than the same boat with much of its ballast in a bulb at the foot of its keel.
• Displacement/Length Ratio (241): This ratio indicates the boat's speed potential. A ratio of 241 classifies the Irwin 54 as a Moderate Displacement boat, which means it requires a moderate amount of sail area to reach its design hull speed.
• Comfort Ratio (39.9): This ratio, created by yacht designer Ted Brewer, is a measure of motion comfort. A ratio of 39.9 suggests that the Irwin 54 has a motion associated with a moderate bluewater cruising boat, which should provide a reasonably comfortable ride in various sea conditions.
• Capsize Screening Formula (1.7): This formula indicates if a boat has blue water capability. A result of 1.7 suggests that the Irwin 54 is better suited for ocean passages rather than coastal cruising, as it has a lower vulnerability to capsize.

It's important to note that these ratios are theoretical and have their limitations. For instance, the Ballast/Displacement Ratio doesn't consider the location of the ballast, which can significantly impact the boat's stability.

Similarly, Ted Brewer's Comfort Ratio favors heavy displacement, narrow-beamed vessels with long overhangs. Therefore, today's light-displacement, beamy cruisers with plumb bows might not score well for crew comfort according to this ratio, even though they may well have bluewater capability.