The SHE 31 Sailboat
Specs & Key Performance Indicators

The SHE 31, a heavy displacement sloop, was designed by Sparkman & Stephens and built in the UK by South Hants Engineering Ltd (hence 'SHE').

A SHE 31 sailboat at anchorThe SHE 31

Published Specification for the SHE 31

Underwater Profile: Fin keel & skeg-hung rudder

Hull Material: GRP (Fibreglass)

Length Overall: 30'4" (9.2m)

Waterline Length: 22'0" (6.7m)

Beam: 8'10" (2.7m)

Draft: 5'5" (1.7m)

Rig Type: Masthead sloop

Displacement: 7,800lb (3,538kg)

Ballast: 3,400lb (1,542kg)

Designer: Sparkman & Stephens

Builder: South Hants Engineering Ltd (UK)

Year First Built: 1969


Published Design Ratios for the SHE 31

1. Sail Area/Displacement Ratio: 16.7

  • 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: 43.6

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

3. Displacement/Length Ratio: 327

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

4. Comfort Ratio: 27.0

  • 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: 1.8

  • 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 SHE 31

1. A Sail Area/Displacement Ratio of 16.7 suggests that the SHE 31 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 43.6 means that the SHE 31 will stand up well to her canvas in a blow, helping her to power through the waves.

3. A Displacement/Length Ratio of 327, tells us the SHE 31 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 27.0 suggests that crew comfort of a SHE 31 in a seaway is similar to what you would associate with the motion of a coastal cruiser with moderate stability, which is not the best of news for anyone prone to seasickness. 

5. The Capsize Screening Formula (CSF) of 1.8 indicates that a SHE 31 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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