The Beneteau Oceanis 381 Sailboat
Specs & Key Performance Indicators

Published Specification for the Beneteau Oceanis 381

Underwater Profile: Bulb fin keel & spade rudder

Hull Material: GRP (Fibreglass)

Length Overall: 38'7" (11.8m)

Waterline Length: 32'10" (10.0m)

Beam: 12'11" (3.9m)

Draft: 5'4" (1.6m)

Rig Type: Masthead sloop

Displacement: 14,991lb (6,800kg)

Designer: Berret-Racoupeau Yacht Design

Builder: Beneteau (France)

Year First Built: 1996

Published Design Ratios for the Beneteau Oceanis 381

1. Sail Area/Displacement Ratio: 15.5

• 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: 31.6

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

3. Displacement/Length Ratio: 189

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

4. Comfort Ratio: 22.2

• 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: 2.1

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Summary Analysis of the Design Ratios for the Beneteau Oceanis 381

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1. A Sail Area/Displacement Ratio of 15.5 suggests that the Beneteau Oceanis 381 will need a stiff breeze to get her going. In light conditions, unless you've got plenty of time on your hands, motor-sailing may be the way to go.

2. A Ballast/Displacement Ratio of 31.6 would usually mean that the Beneteau Oceanis 381 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 189, tells us the Beneteau Oceanis 381 is clearly 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 22.2 suggests that crew comfort of a Beneteau Oceanis 381 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 of 2.1 tells us that a Beneteau Oceanis 381 would not be as good a choice of sailboat for ocean passage-making, owing to the increased risk of capsize in strong winds and heavy seas when compared to a sailboat with a CSF of less than 2.0.