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Sailboat Specifications

Gem 550

Fractional Sloop · Swing Keel

Designed by Rob Humphries · Built by Central Boating Services · First built 1976

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LOA 18.04 ft  ·  Beam 7.91 ft  ·  Displacement 1,146.00 lb  ·  Sail Area 199  ·  Fractional Sloop  ·  Swing Keel
About the Gem 550 Sailboat

With limited specifications available in the public record, the Gem 550 represents one of the more elusive entries in the sailboat database. This scarcity of information often indicates either a limited production run or a regional builder whose documentation hasn't been widely preserved in marine archives. Based on the model designation suggesting a 550 configuration, this sailboat likely falls into the mid-range cruising category, designed for sailors seeking a balance between performance and comfort. Boats of this era and type typically featured practical layouts optimized for coastal cruising and weekend sailing, with sufficient accommodations for extended trips while maintaining manageable sailing characteristics for smaller crews. The Gem nameplate, while not as widely recognized as major production builders, suggests a focus on value-oriented sailing solutions. Without detailed specifications, potential buyers should conduct thorough inspections to assess construction quality, rigging condition, and systems integrity. The limited available data makes this boat particularly suitable for experienced sailors who can evaluate its seaworthiness through hands-on examination rather than relying solely on published specifications. For researchers and potential purchasers, the Gem 550 represents an opportunity to discover a potentially undervalued sailing vessel, though due diligence becomes especially critical given the sparse documentation.

Dimensions & Specifications
LOA (Length Overall) 18.04 ft / 5.50 m
LWL (Waterline Length) 16.67 ft / 5.08 m
Beam 7.91 ft / 2.41 m
Max Draft 3.28 ft / 1.00 m
Min Draft 0.75
Displacement 1,146.00 lb / 520 kg
Ballast 397.00 lb / 180 kg
Sail Area (Reported) 199
Design & Construction
Hull Type Swing Keel
Rigging Type Fractional Sloop
Construction FG
Designer Rob Humphries
Builder Central Boating Services
First Built 1976
Number Built 40
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Frequently Asked Questions

What is the Gem 550's sail area to displacement ratio?

The Gem 550 has a Sail Area to Displacement ratio (SA/D) of 29.13. Values between 14–18 are typical cruising sailboats; 18–22 is cruiser/racer; over 22 is performance racing.

What is the Gem 550's comfort ratio?

The Gem 550 has a Ted Brewer Comfort Ratio of 6.59. A ratio over 30 indicates good offshore comfort; over 40 is very comfortable offshore.

Is the Gem 550 safe for offshore sailing?

The Gem 550 has a Capsize Screening Formula value of 3.03. Values under 2.0 are considered acceptable for offshore sailing; under 1.8 is ideal.

What is the hull speed of the Gem 550?

The theoretical hull speed of the Gem 550 is 5.47 knots, calculated from its waterline length.

How much does a Gem 550 weigh?

The Gem 550 has a displacement of 1,146.00 lb and a length overall (LOA) of 18.04 ft.

Who designed the Gem 550?

The Gem 550 was designed by Rob Humphries, first built in 1976.