The Dufour 455 Sailboat
Specs & Key Performance Indicators

The Dufour 455, a light displacement fractional sloop, was designed by Umberto Felci and built in France by Dufour Yachts.

Dufour 455

Published Specification for the Dufour 455

Underwater Profile: Bulb fin keel & spade rudder

Hull Material: GRP (Fibreglass)

Length Overall: 45'2" (13.8m)

Waterline Length: 39'1" (11.9m)

Beam: 14'2" (4.3m)

Draft: 6'7" (2.0m)

Rig Type: Fractional sloop

Displacement: 22,985lb (10,426kg)

Designer: Umberto Felci

Builder: Dufour Yachts (France)

Year First Built: 2006

Published Design Ratios for the Dufour 455

1. Sail Area/Displacement Ratio: 16.9

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: 28.8

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

3. Displacement/Length Ratio: 172

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

4. Comfort Ratio: 25.6

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 455

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1. A Sail Area/Displacement Ratio of 16.9 suggests that the Dufour 455 will, in the right conditions, approach her maximum hull speed readily and satisfy the sailing performance expectations of most cruising sailors.

2. A Ballast/Displacement Ratio of 28.8 would usually mean that the Dufour 455 would have a tendency to heel uncomfortably 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 her keel, she's likely to be considerably stiffer than her published Ballast/Displacement Ratio might suggest.

3. A Displacement/Length Ratio of 172, tells us the Dufour 455 is a light displacement sailboat. If she's loaded with too much heavy cruising gear her performance will suffer to a degree.

4. Ted Brewer's Comfort Ratio of 25.6 suggests that crew comfort of a Dufour 455 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 1.9 indicates that a Dufour 455 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0.