The Island Packet 40 Sailboat
Specs & Key Performance Indicators

The Island Packet 40, a long-keeled cutter, was designed by Robert K. Johnson and built in the USA by Island Packet Yachts.

An Island Packet 40 sailboat making good progress under full sailAn Island Packet 40 making good progress on a broad reach

Published Specification for the Island Packet 40

Underwater Configuration: Long keel

Hull Material: GRP (fibreglass)

Length Overall: 41′ 6″ (12.68m)

Waterline Length: 34′ 0″ (10.36m)

Beam: 12′ 11″ (3.94m)

Draft: 4′ 8″ (1.42m)

Rig Type: Cutter

Displacement: 22,280 lb

Designer: Robert K. Johnson

Builder: Island Packet Yachts (USA)

Year First Built: 1994

Year Last Built: 2000

Number Built: 139

Published Design Ratios for the Island Packet 40

Sail Area/Displacement: 18.1

  • Less 16 would be considered under-powered;
  • 16 to 20 would indicate reasonably good performance;
  • Over 20 suggests relatively high performance.

Ballast/Displacement: 43.9

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

Displacement/Length: 259

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

Comfort Ratio: 32.6

  • 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

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 all-important numbers...

Summary Analysis of the Design Ratios for the Island Packet 40

1. A Sail Area/Displacement Ratio of 18.1 suggests that the Island Packet 40 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 43.9 means that the Island Packet 40 will stand up well to her canvas in a blow, helping her to power through the waves.

3. A Displacement/Length Ratio of 259, tells us the Island Packet 40 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 32.6 suggests that crew comfort of a Island Packet 40 in a seaway is similar to what you would associate with the motion of a moderate bluewater cruising boat - a predictable and acceptable motion for most seasoned sailors.

5. The Capsize Screening Formula (CSF) of 1.8 tells us that a Island Packet 40 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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