The Sundeer 56 Sailboat
Specs & Key Performance Indicators

The Sundeer 56, an ultra-light fractional sloop, was designed by Steve Dashew and built in the USA by TPI Composites as a shortened version of the Sundeer 60.

'Scraatch', a Sundeer 56 long-distance cruiser at anchor off Ste Anne, Martinique.

Published Specification for the Sundeer 56

  • Underwater Profile: Fin keel & spade rudder
  • Hull Material: GRP (Fibreglass)
  • Length Overall: 56'11" (17.4m)
  • Waterline Length: 56'0" (17.1m)
  • Beam: 13'9" (4.2m)
  • Draft: 6'0" (1.8m)
  • Rig Type: Fractional Sloop
  • Displacement: 34,600lb (15,695kg)
  • Designer: Steve Dashew
  • Builder: TPI Composites (USA)
  • Year First Built: 1994
  • Year Last Built: 1997
  • Number Built: 17

Published Design Ratios for the Sundeer 56

1. Sail Area/Displacement Ratio: 15.7

  • 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: 28.9

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

3. Displacement/Length Ratio: 88.0

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

4. Comfort Ratio: 29.1

  • 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 Sundeer 56

1. A Sail Area/Displacement Ratio of almost 16.0 suggests that the Sundeer 56 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 28.9 means that a sailboat like the Sundeer 56 (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 just 88 places her firmly in the ultralight category. 

4. Ted Brewer's Comfort Ratio of 29.1 suggests that crew comfort of a Sundeer 56 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 1.7 tells us that a Sundeer 56 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0. 

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