The Shannon 28 Sailboat
Specs & Key Performance Indicators

Published Specification for the Shannon 28

Underwater Profile: Fin keel with transom-hung rudder

Hull Material: GRP (Fibreglass)

Length Overall: 28'0" (8.5m)

Waterline Length: 22'11" (7.0m)

Beam: 9'6" (2.9m)

Draft: 4'3" (1.3m)

Rig Type: Cutter

Displacement: 9,300lb (4,218kg)

Designer: Walter Shultz

Builder: Shannon Boat Company (USA)

Year First Built: 1978

Year Last Built: 1985

Number Built: 50

Published Design Ratios for the Shannon 28

1. Sail Area/Displacement Ratio: 17.1

• 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: 38.7

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

3. Displacement/Length Ratio: 345

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

4. Comfort Ratio: 29.3

• 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 Shannon 28

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1. A Sail Area/Displacement Ratio of 17.1 suggests that the Shannon 28 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 38.7 means that a sailboat like the Shannon 28 (which doesn't have its ballast concentrated in a bulb at the foot of a deep keel), is likely to benefit from being reefed early to keep her sailing upright in a moderate breeze.

3. A Displacement/Length Ratio of 345, tells us the Shannon 28 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 ## suggests that the Shannon 28 will have the motion underway to that of a lightweight racing boat. Crew comfort will often be memorable for all the wrong reasons. Upwind in lively conditions the xxxxx will slam enough to shake your fillings out with a motion that most cruising sailors have no desire to get used to.

4. Ted Brewer's Comfort Ratio of 39.3 suggests that crew comfort of a Shannon 28 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 1.8 tells us that a Shannon 28 would be a safer choice of sailboat for an ocean passage than one with a CSF of more than 2.0.