The Slipper 42 Sailboat
Specs & Key Performance Indicators

The Slipper 42, a centre-cockpit ketch, was designed by Robin Chadworth-Musters & Alan Gurney and built in the UK by Tyler Boat Company Ltd.

'Larus', a Slipper 42 Ketch at anchor in Falmouth Harbour, Antigua.A Slipper 42 Ketch

Published Specification for the Slipper 42

Underwater Profile: Fin keel with skeg-hung rudder;

Hull Material: GRP (Fiberglass);

Length Overall: 42'0" (12.8m);

Waterline Length: 30'4" (9.2m);

Beam: 12'3" (3.7m);

Draft: 6'0" (1.8m);

Rig Type: Masthead ketch;

Displacement: 16,500lb (7,484kg);

Designer: Robin Chadworth-Musters & Alan Gurney;

Builder:  Tyler Boat Co. Ltd. (UK);

Year First Built: 1978;

Year Last Built: 1979;

Number Built: 13

Published Design Ratios for the Slipper 42

1. Sail Area/Displacement Ratio: 15.9

  • 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: 43.4

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

3. Displacement/Length Ratio: 264

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

4. Comfort Ratio: 26.8

  • 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: 1.9

  • 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 Slipper 42

1. A Sail Area/Displacement Ratio of 15.9 suggests that the Slipper 42 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 43.4 means that the Slipper 42 will stand up well to her canvas in a blow, helping her to power through the waves.

4. Ted Brewer's Comfort Ratio of 26.8 suggests that crew comfort of a Slipper 42 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 1.9 tells us that a Slipper 42 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0. 

Recent Articles

  1. Used Sailing Equipment For Sale

    Nov 30, 22 01:59 AM

    Here's where people with sailing equipment for sale advertise their stuff entirely free of charge. If you're looking for used sailing gear or other used boating accessories, here's where to find it!

    Read More

  2. Are Heavy Displacement Hulls the Best Choice for Offshore Cruising?

    Nov 27, 22 06:38 AM

    Increasingly, offshore sailboat skippers are choosing moderate displacement hull forms in preference to heavier vessels when planning for an ocean crossing. And here's why...

    Read More

  3. Popular Cruising Yachts from 35 to 40 feet Length Overall

    Nov 22, 22 05:09 AM

    Medium sized cruising yachts like these are often the sailboat of choice for short-handed crews, and if properly equipped and maintained, will take long offshore voyages in their stride.

    Read More