The Jeanneau Sun Fast 39 Sailboat

Specs & Key Performance Indicators

The Jeanneau Sun Fast 39 is primarily crafted for speed and efficiency. This sailboat was designed by French naval architect Daniel Andrieu, known for his expertise in optimizing hull design and performance under sail. The vessel is built by Jeanneau, a company with a longstanding reputation in boat manufacturing based in Les Herbiers, France.

Established in 1957, Jeanneau has evolved to become a renowned builder in the nautical industry, continually integrating innovation with tradition in their wide array of boats. The Jeanneau Sun Fast 39 exemplifies this blend of modern performance features with reliable craftsmanship.

The Sun Fast 39 is a development of the more cruising-oriented Sun Charm 39 of 1988. The design was further developed into the cruising Sun Odyssey 39 in 1990.

A Jeanneau Sun Fast 39 sailboat at anchor

Published Specifications for the Jeanneau Sun Fast 39

Underwater Configuration: Fin keel with spade rudder
Hull Material: Fiberglass
Length Overall: 11.98 meters (39.3 feet)
Waterline Length: 10.95 meters (35.9 feet)
Beam: 3.89 meters (12.8 feet)
Draft:

Standard: 1.95 meters (6.4 feet)
Optional Shallow Draft: 1.50 meters (4.92 feet)

Rig Type: Masthead sloop
Displacement: 7,000 kilograms (15,432 lbs)
Designer: Daniel Andrieu
Builder: Jeanneau (France)
Year First Built: 1991
Year Last Built: 1995

Published Design Ratios for the Jeanneau Sun Fast 39

The Jeanneau Sun Fast 39 sailboat demonstrates several characteristics that can be inferred from its design ratios, which allude to its performance, stability, comfort, and safety capacities. Here’s a breakdown based on the provided ratios:

Sail Area/Displacement Ratio: 20.0 - This ratio suggests the Jeanneau Sun Fast 39 has high performance. With a Sail Area/Displacement Ratio above 20, the boat is expected to be relatively fast and agile, indicating efficient sail power for its weight. This makes it suitable for sailors looking for a spirited sailing experience.

Ballast/Displacement Ratio: 37.7 - The ratio is slightly below 40, which is usually indicative of a stiffer, more powerful boat. While the boat will likely offer good stability, it falls short of the stability seen in boats with higher ratios. However, the actual distribution and location of the ballast in terms of keel design also significantly affect the boat’s stiffness and ability to counterbalance the force of wind on sails.

Displacement/Length Ratio: 188.4 - Falling within the Light Displacement category (100-200), this indicates the boat is lighter relative to its length, which enhances speed and ease of handling. Lighter boats typically require less power to achieve their design speed, but may also be more responsive to sea state changes, impacting their seakeeping abilities.

Comfort Ratio: 21.7 - This places the Jeanneau Sun Fast 39 in the range associated with coastal cruisers (20-30). It suggests adequate comfort for coastal or near-shore journeys but might not have the motion comfort levels desired for extended bluewater passages. Coastal cruisers are designed for relatively shorter, less demanding trips compared to more substantial ocean-going vessels.

Capsize Screening Formula: 2.1 - A score of 2.1 is slightly above the ideal threshold (2.0 or less) for boats better suited for ocean passages. This implies that while the boat has reasonable stability, it might not be optimal for extended offshore sailing in rougher waters, where capsize risks are a more significant concern.

Theoretical nature and limitations of the design ratios:

The Ballast/Displacement Ratio provides insights into potential stability but does not account for the distribution or depth of the ballast. Modern designs often include features like bulb keels that lower the center of gravity and enhance stiffness beyond what this ratio alone can suggest.

Ted Brewer's Comfort Ratio is somewhat biased towards traditional heavy displacement cruisers. Modern vessel designs, which often feature lighter and wider hulls with different bow shapes, may not score as well in terms of theoretical comfort but can still be very capable and safe for bluewater cruising.

Read more about Design Ratios...

Summary: The boat was designed primarily for performance, boasting interior fittings and furnishings of an exceptional standard. It has three double cabins all with good standing area, a comfortable upholstered seat, and plenty of stowage and hanging space. The two aft cabins are mirror images of each other. The galley is equipped with a two-burner stove, an ice box and a double sink. The boat also has a splendid bathing platform built into the transom.

The Jeanneau Sun Fast 39 appears well-designed for enthusiastic performance sailing with a good balance of speed and comfort. It is likely best suited for coastal cruising rather than extended ocean voyages, due to its moderate capsize screening values and comfort ratio. However, these parameters are theoretical and should ideally be augmented by practical assessments and real-world handling characteristics.

The above text was drafted by sailboat-cruising.com using GPT-4 (OpenAI’s large-scale language-generation model) as a research assistant to develop source material; we believe it to be accurate to the best of our knowledge.