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Sailboat Specifications

Island Packet 31

Cutter · Long Keel

Designed by Bob Johnson · Built by Island Packet Yachts (Usa) · First built 1983

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LOA 31.00 ft  ·  Beam 11.60 ft  ·  Displacement 11,000.00 lb  ·  Sail Area 530.00 ft²  ·  Cutter  ·  Long Keel
About the Island Packet 31 Sailboat

Built from 1983 to 1989, this Bob Johnson-designed cruiser represents Island Packet's commitment to seaworthy, comfortable passage-making vessels. With 262 hulls produced during its six-year run, the IP 31 established itself as a popular choice among serious coastal and offshore cruisers seeking a manageable yet capable platform. The boat's long keel configuration and substantial 11,000-pound displacement create exceptional directional stability and a forgiving motion in seas, while the 4,500 pounds of ballast provide reassuring stiffness. The cutter rig arrangement offers versatility in sail handling, particularly valuable when conditions deteriorate offshore. With a comfort ratio of 22.62, this design prioritizes seakindliness over speed, making extended passages notably pleasant for the crew. Island Packet's reputation for quality fiberglass construction shines through in this model, featuring the builder's characteristic attention to structural integrity and finish details. The moderate sail area-to-displacement ratio of 17.2 reflects the design philosophy of steady progress rather than racing performance. While the hull speed of 7.06 knots won't win any races, the boat's ability to maintain course and comfort in challenging conditions has earned it respect among blue-water cruisers who value reliability over speed.

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The IP31 features a balsa-cored deck. Chainplate and stanchion base areas are known trouble spots where water enters core through fastener holes, causing soft spots and rot in the balsa core. Pay particular attention to the area around all deck hardware.
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The long keel on the IP31 uses a cast iron ballast encapsulated within the fiberglass hull. The keel-to-hull interface can develop stress cracks, and any rust staining in the bilge should be investigated as a sign of internal iron corrosion or keel bolt weeping.
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The IP31 uses an interior chainplate system glassed to the inner hull liner. These chainplates are prone to hidden corrosion and are difficult to inspect without removing interior furniture. Weeping rust stains on the liner near the shroud attachments are a warning sign.
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Market Price Estimate Beta
$39,000 – $70,000
typical asking price
Median $50,000  ·  8 listings used
All listings
$39,000 – $70,000 8
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Dimensions & Specifications
LOA (Length Overall) 31.00 ft / 9.45 m
LWL (Waterline Length) 27.75 ft / 8.46 m
Beam 11.60 ft / 3.54 m
Max Draft 4.00 ft / 1.22 m
Displacement 11,000.00 lb / 4,990 kg
Ballast 4,500.00 lb / 2,041 kg
Sail Area (Reported) 530.00 ft² / 49.24 m²
Design & Construction
Hull Type Long Keel
Rigging Type Cutter
Construction FG
Designer Bob Johnson
Builder Island Packet Yachts (USA)
First Built 1983
Last Built 1989
Number Built 262
Associations Official Island Packet Yacht Owners Association
Owner Reviews

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Engine & Accommodations
Engine Type Diesel
Horsepower 27
Fuel Capacity 25 gals / 95 L
Water Capacity 70 gals / 265 L
Frequently Asked Questions

What is the Island Packet 31's sail area to displacement ratio?

The Island Packet 31 has a Sail Area to Displacement ratio (SA/D) of 17.2. Values between 14–18 are typical cruising sailboats; 18–22 is cruiser/racer; over 22 is performance racing.

What is the Island Packet 31's comfort ratio?

The Island Packet 31 has a Ted Brewer Comfort Ratio of 22.62. A ratio over 30 indicates good offshore comfort; over 40 is very comfortable offshore.

Is the Island Packet 31 safe for offshore sailing?

The Island Packet 31 has a Capsize Screening Formula value of 2.09. Values under 2.0 are considered acceptable for offshore sailing; under 1.8 is ideal.

What is the hull speed of the Island Packet 31?

The theoretical hull speed of the Island Packet 31 is 7.06 kn knots, calculated from its waterline length.

How much does a Island Packet 31 weigh?

The Island Packet 31 has a displacement of 11,000.00 lb and a length overall (LOA) of 31.00 ft.

How much does a used Island Packet 31 cost?

Based on 8 recent market listings, used Island Packet 31 sailboats typically sell for between $39,000 and $70,000, with a median asking price of $50,000. Price varies significantly based on year, condition, location, and included equipment.

Who designed the Island Packet 31?

The Island Packet 31 was designed by Bob Johnson, first built in 1983.