The Najad 391 Sailboat
Specs & Key Performance Indicators

Published Specification for the Najad 391

Underwater Profile: Fin keel and skeg-hung rudder

Hull Material: GRP (Fibreglass)

Length Overall: 39'9" (12.1m)

Waterline Length: 33'2" (10.1m)

Beam: 11'11" (3.6m)

Draft: 6'3" (1.9m)

Rig Type: Masthead sloop

Displacement: 22,046lb (10,000kg)

Designer: Thorwald Karlsson

Builder: Najad Varvet AB (Sweden)

Year First Built: 1995

Year Last Built: 2003

While the Najad 391 shares many similarities with the earlier Najad 390, the Najad 391 is considered an upgrade from the 390 with improvements in hull, keel, and rudder design leading to an enhanced sailing performance.

Published Design Ratios for the Najad 391

• With a Sail Area/Displacement Ratio of 16.9, the boat is in the range that indicates reasonably good performance, suggesting it can handle a moderate amount of sail power relative to its weight.

• The Ballast/Displacement Ratio of 42.0 points to a potentially stiffer and more powerful boat capable of standing up better to wind, though this ratio does not account for ballast placement, which can significantly impact actual performance.

• The Displacement/Length Ratio of 270 categorizes this vessel within the moderate displacement range, which implies a balance between speed and comfort in various sea conditions, without needing excessive sail area to achieve hull speed.

• Its Comfort Ratio of 35.8 classifies it as a moderate bluewater cruising boat, suggesting it will have a less abrupt motion at sea, which is preferable for comfort on longer passages.

• Lastly, a Capsize Screening Formula of 1.7 indicates a strong suitability for ocean passages, as it falls well within the range suggesting greater stability and safety in rough waters.

However, it is important to note the theoretical nature of these values, particularly the limitations of the Ballast/Displacement Ratio that doesn't consider the depth or concentration of ballast. Additionally, the Comfort Ratio can disproportionately favor traditionally designed heavy displacement boats over more modern light-displacement designs, which may not be less capable but simply differently balanced in design priorities.

Therefore, while these ratios provide a helpful initial assessment, actual performance and comfort should be validated through real-world sailing experience and reviews.