Stories with Tag sailing

• How a yacht works: sailboat physics and design

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  Posted: 2025-04-15 21:19:33

  Verbose tl;dr

  Sailboats harness the wind to generate propulsive force through aerodynamic principles. The sails, acting as airfoils, create a pressure difference, generating lift perpendicular to the wind. This lift force can be resolved into two components: one pushing the boat sideways (leeway), and the other propelling it forward. The keel or centerboard counteracts leeway, allowing the boat to move efficiently against the wind by sailing at an angle. Sail shape, hull design, and appendage configuration are crucial for optimizing performance, balancing stability and speed. Different sail types and trims are used depending on the wind direction and strength, allowing sailors to adjust to varying conditions and desired points of sail.

  This comprehensive article delves into the intricate world of sailboat design and the underlying physics that govern their movement, exploring the delicate interplay of forces that allow these vessels to harness the power of the wind for propulsion. It begins by elucidating the fundamental principle of sailing: generating lift through the interaction of the sail and the wind, analogous to the aerodynamic principles that enable airplane flight. The sail, acting as an airfoil, curves the airflow around its surface, creating a pressure difference – lower pressure on the leeward side and higher pressure on the windward side. This pressure differential results in a net force perpendicular to the apparent wind direction, a force that can be resolved into two components: thrust, which propels the boat forward, and heeling force, which pushes the boat sideways.

  The article then meticulously dissects the different types of sails and their specific functions, differentiating between the mainsail and the jib, and explaining how their combined operation contributes to generating the necessary lift. It emphasizes the importance of sail shape and trim in optimizing performance, illustrating how adjustments to sail controls like the halyard, sheet, and outhaul can influence the curvature of the sail and thus the lift generated. Furthermore, it underscores the role of the center of effort, the point where the resultant force from the sails acts, and the center of lateral resistance, the point where the hydrodynamic resistance of the hull and keel opposes the heeling force, in maintaining equilibrium and preventing capsize.

  The article further elaborates on the significance of keel design in providing stability and counteracting the heeling force. It distinguishes between different keel configurations, explaining how fin keels, bulb keels, and bilge keels contribute to hydrodynamic lift, which opposes leeway, the sideways drift of the boat. This lateral resistance, coupled with the righting moment generated by the keel's weight and its distance from the centerline, allows the sailboat to maintain an upright position even under strong winds.

  Moreover, the piece explores the complex interplay between apparent wind, the wind experienced by the boat while in motion, and true wind, the actual wind direction and speed. It describes how the apparent wind shifts forward as the boat gains speed, enabling sailboats to sail at angles closer to the wind than one might initially expect. This "sailing close-hauled" is crucial for navigating upwind and is a testament to the sophisticated interplay of aerodynamic and hydrodynamic forces at play.

  Finally, the article touches upon other design considerations, including hull shape and rudder design, highlighting how these elements contribute to the overall performance and maneuverability of the sailboat. It elucidates the importance of minimizing drag and maximizing efficiency in hull design, and the role of the rudder in controlling the direction of the boat. In essence, the article provides a thorough and insightful overview of the physics and design principles that underpin the art of sailing, demonstrating the intricate balance of forces that allows these vessels to harness the wind and navigate the waters with grace and precision.

  • yacht
  • sailboat
  • sailing
  • physics
  • design
  • naval architecture
  • hydrodynamics
  • aerodynamics
  • keel
  • rudder
  • sail
  • mast
  • hull
  • Marine Engineering
  • boat design

  Summary of Comments ( 1 )
  https://news.ycombinator.com/item?id=43698522

  Verbose tl;dr

  HN commenters largely praised the article for its clear explanations of complex sailing concepts like apparent wind, sail trim, and heeling forces. Several appreciated the interactive diagrams, highlighting their effectiveness in illustrating how these forces interact. Some commenters with sailing experience shared personal anecdotes and added further details, expanding upon points made in the article, such as the importance of sail shape and the challenges of heavy weather sailing. A few mentioned the site's outdated design but emphasized that the quality of the content outweighed the aesthetic shortcomings.

  The Hacker News post "How a yacht works: sailboat physics and design" linking to onemetre.net sparked a moderate discussion with 16 comments. Several commenters praised the clarity and comprehensiveness of the linked article. One user, pjmlp, appreciated the "excellent diagrams and explanations" particularly regarding apparent wind, a concept they found often poorly explained elsewhere. Another, sp332, simply stated it was a "great explanation." throwaway30012 agreed, specifically highlighting the explanation of heeling force and righting moment as being "well explained."

  A recurring theme in the comments was the comparison of different sailboat designs. toomuchtodo pointed out the advantages of multihulls over monohulls in terms of speed and stability, referring to monohulls as "slow and tippy." This spurred a small discussion about the trade-offs, with yters countering that monohulls offer a more engaging and "fun" sailing experience, despite their performance disadvantages. They elaborated that the heeling and responsiveness of a monohull provides more feedback and a closer connection to the forces at play. sp332 further contributed to this comparison by mentioning the reduced wetted surface area of multihulls as a key factor in their speed.

  The discussion also briefly touched on the complexities of sail trim. throwaway30012 noted the subtleties involved in adjusting sail shape for optimal performance in varying wind conditions. However, this point wasn't elaborated on further by other commenters.

  Finally, there was a minor tangential discussion about the use of computational fluid dynamics (CFD) in modern yacht design, initiated by pjmlp. They mentioned the prevalence of CFD analysis in optimizing hull shapes and sail designs, acknowledging its significance in pushing the boundaries of performance.

  Overall, the comments on the Hacker News post generally praised the linked article for its accessible explanation of sailing principles. The discussion also touched upon some broader topics within sailing, such as the advantages and disadvantages of different hull designs, the intricacies of sail trim, and the role of modern technology like CFD in yacht design.

• Pirates and Privateers – Superstitions and the Sea (2007)

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  Posted: 2025-02-06 09:49:36

  Verbose tl;dr

  Sailors, including pirates and privateers, were highly superstitious due to the unpredictable and dangerous nature of the sea. They believed in a variety of omens and rituals to appease the sea and ensure good fortune. These included avoiding whistling aboard ship (believed to summon storms), respecting certain creatures like dolphins and albatrosses, and performing specific actions on certain days, such as not sailing on a Friday. Many superstitions arose from practical concerns, like the prohibition against red clothing due to its similarity to the color of blood, which could demoralize the crew. These beliefs and practices, while seemingly irrational, provided a sense of control and order in a chaotic environment.

  Cindy Vallar's 2007 blog post, "Pirates and Privateers – Superstitions and the Sea," delves into the rich tapestry of maritime superstitions prevalent during the Golden Age of Piracy, exploring the beliefs and practices that both shaped and reflected the lives of seafaring individuals, particularly those engaged in piracy and privateering. Vallar meticulously illustrates how these superstitions, often rooted in ancient folklore and practical observations of the unpredictable ocean environment, permeated virtually every aspect of a sailor's existence.

  The article commences by establishing the inherent dangers and uncertainties of life at sea, highlighting how the constant threat of storms, shipwrecks, disease, and violent encounters fostered a climate of anxiety and superstition among sailors. This environment, where life and death often hung precariously in the balance, naturally led seafarers to seek methods, however irrational, to control their fate and appease the seemingly capricious forces of nature. Vallar then proceeds to catalogue a fascinating array of specific superstitions, meticulously explaining their origins and the rituals associated with them.

  Among these superstitions, Vallar discusses the ill-omen associated with whistling aboard a ship, believed to summon unfavorable winds, and the taboo of cutting one's hair or nails at sea, linked to bad luck. She also explores the belief in the protective power of carrying a lucky coin or charm, a tangible representation of hope in a world dominated by chance. The significance of certain animals, such as albatrosses and dolphins, is also examined, with some considered harbingers of good fortune while others portended disaster.

  Furthermore, the post delves into the intriguing practices surrounding death and burial at sea, revealing the solemn rituals observed by sailors to appease the spirits of the departed and ensure safe passage for the living. Vallar elaborates on the superstitions related to women aboard ships, often seen as a source of misfortune, likely stemming from practical concerns about distractions and potential conflicts in the close quarters of a vessel.

  The role of Fridays, especially Friday the 13th, as a day of ill-omen is also examined, highlighting the deep-seated fear associated with this particular day. Vallar also explores the belief in mythical creatures of the sea, such as mermaids and sirens, and their purported influence on sailors' fortunes. The discussion extends to the superstitions surrounding specific actions, like embarking on a voyage on a certain day of the week or starting a voyage with an empty wallet, emphasizing the meticulous attention paid to even seemingly trivial details in an attempt to ensure a successful journey.

  Throughout the post, Vallar carefully distinguishes between the superstitions adhered to by common sailors and those specifically attributed to pirates and privateers, acknowledging that while there was considerable overlap, certain beliefs were more prominent within these specific groups. In concluding, Vallar emphasizes that these superstitions, though seemingly irrational to modern sensibilities, provide a valuable window into the mindset and worldview of sailors during the Golden Age of Piracy, offering a deeper understanding of their fears, hopes, and the challenges they faced in navigating the perilous world of the sea. The post effectively demonstrates how these seemingly fantastical beliefs served a practical purpose, providing a sense of control and order in an environment characterized by uncertainty and peril.

  • pirates
  • privateers
  • superstitions
  • maritime history
  • nautical folklore
  • sea shanties
  • naval history
  • sailing
  • age of sail
  • 2007
  • cindy vallar

  Summary of Comments ( 0 )
  https://news.ycombinator.com/item?id=42960772

  Verbose tl;dr

  HN users discuss the practicality of some of the superstitions mentioned in the article, like avoiding whistling at sea (could be mistaken for piped orders) and not setting sail on a Friday (historically a common day for executions, making crews uneasy). Some commenters share additional maritime superstitions, including ones about bananas, redheads, and sharks following a ship. Several recall personal experiences or anecdotes related to seafaring superstitions, highlighting their enduring presence in nautical culture, even if not always taken seriously. The role of superstition in creating a sense of shared experience and camaraderie among sailors is also touched upon.

  The Hacker News post discussing the article "Pirates and Privateers – Superstitions and the Sea" has generated a moderate amount of discussion with a mix of humorous and insightful comments. Several commenters focus on specific superstitions mentioned in the linked article, elaborating on their origins or providing additional context.

  One commenter highlights the superstition regarding bananas on ships, suggesting it stems from poisonous spiders being transported along with the fruit, leading to illness and even death among crew members. They also mention the possibility of bananas emitting ethylene gas, which could spoil other food stored onboard, further contributing to the negative association.

  Another commenter focuses on the "no whistling" superstition, offering two potential explanations. Firstly, they suggest whistling might have been associated with summoning unfavorable winds. Secondly, they propose that whistling could have been seen as interfering with the important auditory cues sailors relied on in the pre-engine era, such as the sounds of the waves and wind.

  A third commenter touches on the "red sky at night, sailor's delight" proverb, providing a meteorological explanation. They explain that a red sky at night often indicates high pressure and stable air to the west, which is the direction from which weather typically travels in mid-latitudes. This implies good weather is approaching. Conversely, a red sky in the morning suggests the high pressure has already passed, and the observer is now facing the unsettled, possibly stormy weather coming from the west.

  Some commenters engage in lighter banter, jokingly linking the "Friday being an unlucky day to sail" superstition to the release schedule of software updates, humorously suggesting that deploying updates on Fridays often leads to problems and sleepless nights.

  In addition to these specific discussions, some users share related anecdotes about superstitions in other professions, such as theater and aviation. This expands the conversation beyond maritime superstitions, exploring the broader theme of superstitions in high-risk occupations.

  While the overall volume of comments is not exceptionally high, the discussion provides interesting perspectives and expansions on the superstitions mentioned in the original article. The comments are a mix of informative explanations, humorous takes, and personal anecdotes, offering a well-rounded view of the topic.