Sail area / displacement
How much sail the boat carries for its weight — its power in light air.
- 34.4· Racing
How it is worked out
sail area (ft²) ÷ (displacement as ft³ of seawater)^⅔
mainsail + jib, added up

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Swan 108 sailing — Nautor Swan
* A standard reference image, not the actual boat — shown to help visualise this model's published dimensions.
Classic yacht-design ratios worked out from the builder's published figures, each shown against the bands designers read it by.
How much sail the boat carries for its weight — its power in light air.
sail area (ft²) ÷ (displacement as ft³ of seawater)^⅔
mainsail + jib, added up
How heavy the boat is for its waterline length. Lower is lighter and quicker; higher is steadier and roomier.
displacement (long tons) ÷ (0.01 × waterline length in ft)³
The share of the weight carried in the keel — a rough guide to stiffness, though how deep that weight sits matters as much.
ballast ÷ displacement × 100
Ted Brewer's measure of how gently a boat moves in a seaway. Higher means a slower, easier motion.
displacement (lb) ÷ (0.65 × (0.7 × LWL + 0.3 × LOA) × beam^1.333), lengths in ft
A guide from the inquiry after the 1979 Fastnet race: below 2 was taken as suited to ocean passages. It ignores hull shape and where the ballast sits.
beam (ft) ÷ (displacement as ft³ of seawater)^⅓
Roughly the speed a displacement hull reaches before it has to climb its own bow wave.
1.34 × √(waterline length in ft), in knots
Most builders publish a light displacement. The ratios were defined on a loaded boat, so every boat here reads a little lighter than a surveyor's figure would — all alike, which keeps them comparable.
What the builder publishes about how fast, how strong and how much the boat carries.
Fuel and water on one scale: a tank twice the height holds twice as much.
A figure marked with a quote mark was read from the builder's page. Open it for the exact line, the page and the date.
Figures read fromthe builder's page
1 drawing from the builder's page: general arrangement, sail plan, profile.

swan108 sailplan concept standard — Nautor Swan
Premium production
Finnish builder of luxury sailing yachts, founded in 1966 in Pietarsaari and known worldwide as Nautor Swan.
Oy Nautor AB was founded in 1966 by Pekka Koskenkylä at Pietarsaari, Finland, on centuries of Finnish boatbuilding and a wish to build high-performance sailing yachts of high quality. The first was the Swan 36, whose glass-reinforced hull came with a number of other innovations: it matched the traditional wooden yacht for performance and safety while steering more steadily, weighing less and offering more room below. Sparkman & Stephens drew roughly the first thousand Swans, the Swan 38 and Swan 47 among them, and the larger, seagoing Swan 55 and Swan 65 followed -- one of them, Sayula II, winning the first Whitbread Round the World Race in 1973-74. Ron Holland designed five yachts between 1978 and 1981, including the Swan 37, 39 and 42, and Germán Frers became the principal designer through the 1980s, later opening the one-design racing division with the Swan 45 in 2001 and the ClubSwan 42 in 2005. More than 2,350 yachts between 28 and 131 feet have been built in six decades. Everything is made at Pietarsaari, where engineering sits beside production, and the range now runs across six lines: Swan, Swan Maxi, ClubSwan, Swan Alloy, SwanScape and the motor yacht division Swan Shadow.
Visit brand pageEvery model Nautor Swan publishes, by length — where this one sits in the range.
Boats this boat's designers also drew, for other builders too. Credits are grouped only where the names clearly agree, however each builder spelled them; an unclear one is left out.