Published Design Ratios for the Swan 59
1. Sail Area/Displacement Ratio: Not published
- 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: 36.5
- Under 40: less stiff, less powerful
- Over 40: stiffer, more powerful
3. Displacement/Length Ratio: 250
- Under 100: Ultralight
- 100 to 200: Light
- 200 to 275: Moderate
- 275 to 350: Heavy
- Over 350: Ultraheavy
4. Comfort Ratio: 45.3
- 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 59
1. The Sail Area/Displacement Ratio of the Swan 59 is not published, hence we are unable to comment on this aspect of the boat's predicted performance.
2. A Ballast/Displacement Ratio of 36.5 means that a sailboat like the Swan 59 (which doesn't have its ballast concentrated in a bulb at the foot of a deep keel), is likely to benefit from being reefed early to keep her sailing upright in a moderate breeze.
3. A Displacement/Length Ratio of 250, tells us the Swan 59 is a moderate displacement cruiser, which means she'll carry all your cruising gear without it having a dramatic effect on her performance. Most of today's sailboats intended for offshore cruising fall into this displacement category.
4. Ted Brewer's Comfort Ratio of 45.3 suggests that crew comfort of a Swan 59 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 59 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0.