The Dufour 40e Sailboat
Specs & Key Performance Indicators

The Dufour 40e, a light-displacement fractional sloop, was designed by Umberto Felci and Patrick Roséo and built in France by Dufour Yachts.

A Dufour 40e 'Ker Yamm' at anchor in Deep Bay, Antigua

Published Specification for the Dufour 40e

Underwater Profile: Bulb fin keel and spade rudder

Hull Material: GRP

Length Overall: 40'5" (12.4m)

Waterline Length: 35'3" (10.8m)

Beam: 12'9" (3.9m)

Draft: 6'10" (2.1m)

Rig Type: Fractional sloop

Displacement: 16,283lb (7,386kg)

Designer: Umberto Felci and Patrick Roséo

Builder: Dufour Yachts (France)

Year First Built: 2002

Owners Association: Dufour Owners Association

Published Design Ratios for the Dufour 40e

1. Sail Area/Displacement Ratio: 23.8

Less than 16 would be considered under-powered;
16 to 20 would indicate reasonably good performance;
Over 20 suggests relatively high performance.

2. Ballast/Displacement Ratio: 30.0

Under 40: less stiff, less powerful
Over 40: stiffer, more powerful

3. Displacement/Length Ratio: 178

Under 100: Ultralight
100 to 200: Light
200 to 275: Moderate
275 to 350: Heavy
Over 350: Ultraheavy

4. Comfort Ratio: 24.7

Under 20 indicates a lightweight racing boat
20 to 30 indicates a coastal cruiser
30 to 40 indicates a moderate offshore cruising boat
40 to 50 indicates a heavy offshore boat
Over 50 indicates an extremely heavy offshore boat

5. Capsize Screening Formula: 2.0

Under 2.0 (the lower the better): Better suited for ocean passages
Over 2.0: Less suited for ocean passages

Summary Analysis of the Design Ratios for the Dufour 40e

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1. A Sail Area/Displacement Ratio of 23.8 suggests that, in the right hands, the Dufour 40e will have enough performance to leave most other sailboats of similar waterline length well astern.

2. A Ballast/Displacement Ratio of 30.0 would usually mean that the Dufour 40e would have a tendency to heel excessively in a gust, and need to be reefed early to keep her sailing upright in a moderate breeze.

However, as she has much of her ballast concentrated in a bulb at the foot of the keel, she's likely to be considerably stiffer than her published Ballast/Displacement Ratio might suggest.

3. A Displacement/Length Ratio of 178, tells us the Dufour 40e is clearly a light displacement sailboat. If she's loaded with too much heavy cruising gear her performance will suffer dramatically.

4. Ted Brewer's Comfort Ratio of 24.7 suggests that crew comfort of a Dufour 40e in a seaway is similar to what you would associate with the motion of a coastal cruiser with moderate stability, which is not encouraging news for anyone prone to seasickness.

5. The Capsize Screening Formula (CSF) of 2.0 indicates that a Dufour 40e would not be the wisest choice of sailboat for ocean passage-making owing to the lower resistance to capsize in strong winds and heavy seas that is associated with sailboats with a CSF of 2.0 and above.