The Swan 48 Sailboat
Specs & Key Performance Indicators

Published Specification for the Swan 48

Underwater Configuration: Fin keel & skeg-hung rudder

Hull Material: GRP (Fibreglass)

Length Overall: 47'11" (14.6m)

Waterline Length: 37'3" (11.4m)

Beam: 13'7" (4.2m)

Draft: 7'9" (2.4m)

Rig Type: Masthead sloop

Displacement: 36,000lb (16,330kg)

Designer: Sparkman & Stephens

Builder: Nautor (Finland)

Year First Built: 1971

Year Last Built: 1975

Number Built: 46

Owners Association: S&S Swan Owners Association

Published Design Ratios for the Swan 48

1. Sail Area/Displacement Ratio: 15.2

• 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: 39.2

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

3. Displacement/Length Ratio: 310

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

4. Comfort Ratio: 42.5

• 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: 1.7

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

read more about these Key Performance Indicators...

Summary Analysis of the Design Ratios for the Swan 48

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1. A Sail Area/Displacement Ratio of 15.2 suggests that the Swan 48 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 39.2 means that the Swan 48 will have a tendency to heel excessively in a gust, and she'll need to be reefed early to keep her sailing upright in a moderate breeze. 

3. A Displacement/Length Ratio of 310, tells us the Swan 48 is clearly a heavy displacement cruising boat. You can load her down with all your cruising gear and equipment and it will hardly affect her waterline. Not an ideal choice for coastal sailing, but she'll come into her own on an offshore passage in testing conditions.

4. Ted Brewer's Comfort Ratio of 42.5 suggests that crew comfort of a Swan 48 in a seaway is similar to what you would associate with the motion of a heavy bluewater cruising boat. Pitching and rolling will be well damped - your cup of coffee on the salon table stands a reasonable chance of staying there in most conditions.

5. The Capsize Screening Formula (CSF) of 1.7 tells us that a Swan 48 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0.