The Island Packet 350 Sailboat
Specs & Key Performance Indicators

The Island Packet 350, a long-keeled cutter, was designed by Bob Johnson and built in the USA by Island Packet Yachts.

An Island Packet 350

Published Specification for the Island Packet 350

Underwater Profile: Long keel

Hull Material: GRP (Fibreglass)

Length Overall: 34'8" (10.6m)

Waterline Length: 29'4" (8.9m)

Beam: 12'0" (3.7m)

Draft: 4'3" (1.3m)

Rig Type: Cutter

Displacement: 16,000 lb (7,257 kg)

Designer: Bob Johnson

Builder: Island Packet Yachts (USA)

Year First Built: 1997

Year Last Built: 2004

Published Design Ratios for the Island Packet 350

1. Sail Area/Displacement Ratio: 18.3

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: 46.9

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

3. Displacement/Length Ratio: 283

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

4. Comfort Ratio: 29.2

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

Summary Analysis of the Design Ratios for the Island Packet 350

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1. A Sail Area/Displacement Ratio of 18.3 suggests that the Island Packet 350 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 46.9 means that the Island Packet 350 will stand up well to her canvas in a blow, helping her to power through the waves.

3. A Displacement/Length Ratio of 283, tells us the Island Packet 350 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 29.2 suggests that crew comfort of a Island Packet 350 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 an Island Packet 350 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0.