The Atlantic 49 Sailboat
Specs & Key Performance Indicators

The Atlantic 49 sailboat, designed by J & J Design, a Slovenian design firm, is constructed by Anassis-Raptis, a builder based in Greece.

An Atlantic 49 sailboat at anchor

Published Specification for the Atlantic 49 Sailboat

Keel & Rudder Configuration: Fin keel with rudder on skeg
Hull Material: Fiberglass
Length Overall: 14.94 meters (49'0")
Waterline Length: 14.36 meters (47'2")
Beam: 4.58 meters (15'0")
Draft: 2.00 meters (6'6")
Rig Type: Masthead Sloop
Displacement: 12,000 kg (26,455 lbs)
Ballast: 3,800 kg (8,377 lbs)
Water Tank Capacity: 800 liters (211 gallons)
Fuel Tank Capacity: 370 liters (97 gallons)
Hull Speed: 8.6 knots
Designer: J & J Design
Builder: Anassis-Raptis
Year First Built: 1990

Sail Areas & Rig Dimensions

I: 18.00 meters (59.06 feet)
J: 5.50 meters (18.04 feet)
P: 15.50 meters (50.85 feet)
E: 5.20 meters (17.06 feet)

Published Design Ratios
The Key Performance Indicators (KPIs)

The Atlantic 49 sailboat has the following design ratios:

Sail Area to Displacement Ratio (SA/D): 17.0
Ballast to Displacement Ratio (B/D): 31.67%
Displacement to Length Ratio (D/L): 167
Comfort Ratio: 23.24
Capsize Screening Formula (CSF): 2.02

Here's how to calculate the KPIs yourself - without having to wrestle with the mathematics...

With a Sail Area to Displacement Ratio of 17.0, the Atlantic 49 falls into the range indicating reasonably good performance. This suggests that the sailboat has a decent power-to-weight ratio and should perform well under sail, providing a balance between performance and comfort.

A Ballast to Displacement Ratio of 31.67% means this sailboat has a moderate amount of ballast. It won't be as stiff or powerful in standing up to the wind compared to boats with a B/D ratio of 40 or more. However, it should provide a reasonable compromise between stability and performance.

With a Displacement to Length Ratio of 167, the Atlantic 49 falls into the "Light Displacement" category. This indicates that the boat is relatively easy to drive to its hull speed with a moderate amount of sail area. It implies better acceleration and more responsive handling, characteristics often associated with more agile and quicker sailboats.

A Comfort Ratio: of 23.24 suggests that the Atlantic 49 has a motion typical of a coastal cruiser with moderate stability. It should provide a reasonable level of comfort in coastal cruising conditions, making it suitable for family outings and less demanding passages. However, in rougher seas, it might not be as comfortable as boats with higher comfort ratios.

With a Capsize Screening Formula of 2.02, the Atlantic 49 is right on the threshold for blue water capability. While it is marginally suited for ocean passages, care should be taken, particularly in rough conditions. Generally, boats with a CSF of 2.0 or less are considered better suited for extended offshore cruising.

Summary
The Atlantic 49 sailboat is a well-balanced coastal cruiser with good performance capabilities and moderate stability. It is designed to be relatively easy to handle and offers a reasonable level of comfort for coastal cruising. While it can be used for blue water passages, it is on the borderline, so it's better suited for shorter or less demanding ocean trips. The balance of these characteristics makes it a versatile choice for sailors who want a boat that performs well in a variety of conditions without being overly specialized.

Design Ratios: Notes of Caution...

The Sail Area/Displacement Ratio (SA/D): This ratio provides an estimate of the sail power relative to the boat's weight, which can indicate potential speed in various wind conditions. But it doesn't account for the efficiency of the sail plan, the rigging, or the skill of the crew. Real-world performance can vary significantly based on these factors.

The Ballast/Displacement Ratio (B/D): This ratio gives an idea of the boat's stability and stiffness, which is crucial for handling and safety. But it doesn't consider the distribution of the ballast or the hull shape, both of which can greatly affect stability. A high B/D ratio alone doesn't guarantee a stable boat if the ballast is poorly distributed.

The Displacement/Length Ratio (D/L): This ratio helps predict the boat's speed potential and its behaviour in different sea conditions. But it doesn't account for the hull design or the boat's overall weight distribution. Two boats with the same D/L ratio can perform very differently if their hull shapes are different.

The Comfort Ratio (CR): This ratio estimates the boat's motion comfort in a seaway, which is important for long passages. But it doesn't consider the boat's interior layout, which can also affect comfort. Additionally, personal tolerance to motion varies, so a boat that is comfortable for one person might not be for another.

The Capsize Screening Formula (CSF): This formula assesses the likelihood of a boat capsizing in heavy seas, which is critical for offshore safety. But it doesn't take into account the boat's handling characteristics or the skill of the crew. A boat with a low CSF can still capsize if poorly handled in severe conditions.

General Limitations

Static Nature: These ratios are static measurements and don't account for dynamic factors like wave action, wind gusts, or crew actions.

Simplification: They simplify complex interactions into single numbers, which can be misleading. Real-world performance is influenced by a multitude of factors that these ratios can't fully capture.

Context: The context in which the boat is used (e.g., coastal cruising vs. offshore racing) can greatly affect how these ratios should be interpreted.

In summary, while these ratios provide valuable insights into the theoretical performance characteristics of a sailboat, they should be used as part of a broader assessment that includes practical experience, sea trials, and expert advice.

This article was written with the assistance of Gemini, a large language model developed by Google. Gemini was used to gather information, summarize research findings, and provide suggestions for the content and structure of the article.