What is Sailing: Definition and 26 Discussions

Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the water (sailing ship, sailboat, windsurfer, or kitesurfer), on ice (iceboat) or on land (land yacht) over a chosen course, which is often part of a larger plan of navigation.
Until the middle of the 19th century, sailing ships were the primary means for marine exploration, commerce, and projection of military power; this period is known as the Age of Sail. In the 21st century, most sailing represents a form of recreation or sport. Recreational sailing or yachting can be divided into racing and cruising. Cruising can include extended offshore and ocean-crossing trips, coastal sailing within sight of land, and daysailing.
Sailing relies on the physics of sails as they derive power from the wind, generating both lift and drag. On a given course, the sails are set to an angle that optimizes the development of wind power, as determined by the apparent wind, which is the wind as sensed from a moving vessel. The course with respect to the true wind direction (as sensed from a stationary location) is called a point of sail. Conventional sailing craft cannot derive power from sails on a point of sail that is facing too close into the wind. The forces transmitted via the sails are resisted by forces from the hull, keel, and rudder of a sailing craft, by forces from skate runners of an iceboat, or by forces from wheels of a land sailing craft to allow steering the course.

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  1. U

    I Fluid dynamics of sailing boat when steering

    1. Is it possible that sailing boat(going backward) turns less when rudder is full right, then rudder is at some smaller angle? Due to too high AoA and flow separation/stall, trailing edge of rudder is sharp that also lower stall AoA... 2. Analysis waterflow when object move at curved path...
  2. BWV

    Sailing drone video from inside cat 4 hurricane

    https://www.saildrone.com/press-release/ocean-drone-captures-video-inside-category-4-hurricane The Saildrone Explorer SD 1045 was directed into the midst of Hurricane Sam, which is currently on a path that fortunately will miss the US East Coast. SD 1045 is battling 50-foot waves and winds of...
  3. infinitebubble

    Sailing for Inner Peace: Find Relaxation and Excitement

    Who here goes sailing into the night? Anyone here sailors or owners of a sailboat/catamaran? I sail often and find it calms the exhaustion of the week. Though relaxing and transcendence to a time far away only when I'm fishing and pulling in a large fish does it really get exciting! Anyone relate?
  4. Jezza

    Exploring the Mystery of Hull Speed: The Online vs. Textbook Debate

    There is a well known rule of thumb amongst sailors that a boat has a theoretical maximum speed called the hull speed, given by v_h \approx 1.34 \sqrt{L_{wl}}, where LWL is the waterline length of the hull. This so-called rule is pretty much complete rubbish; a boat can overcome this speed with...
  5. Hercuflea

    Sailboat Speed Question: Can a Motor Increase Speed Beyond 10 Knots with Sails?

    This is not a homework question, I'm just curious. Suppose you had a sailboat sailing on calm water. Let's say the sailboat is capable of sailing at 10 knots under the current wind conditions using only its sails. Now say the sailboat had a small propeller motor that was capable of propelling...
  6. tech99

    Can a sailing boat go faster than the wind when going in the downwind direction?

    If a sailing boat is running before the wind, i.e. with the wind exactly behind, is it possible for it to go faster than the wind? If one thinks of a wind generator on the boat it could perhaps operate an electric propulsion motor to give any desired speed? But what about the apparent wind when...
  7. W

    Calculate sailing ship drag, or anyway any drag of any shape

    Hello there, I'm trying to write a sailing model simulator (for ships with sails) i got buoyancy force and gravity force calculated so far. Before i go any further i need to tell you how i am calculating anything, and what is my ship exactly. First of all i am making that on a phone, it looks...
  8. E

    Calculating the forward force of a sailboat

    Sails can propel a boat in two ways. The first occurs simply when sailing with the wind (downwind) where the sail is set perpendicular to the wind to proved the greatest surface area. The air decelerates as it hits the sail omitting a force onto the sail. As a result, according to Newton's 3rd...
  9. L

    Lyman in Tampa Florida. Transplanted Canadian, eh~

    Old timer in electronics. Small defense contracting business and manufacturing our own products mostly for Ship's at Sea. Ex Ship's Radio Officer, Avionics engineer, ex Marconi, traveled 65 countries, photographer, pilot, scuba. I will be 71 next month. Was long distance solo cruiser on my...
  10. S

    Sailing along multiple Bearings Problem

    Homework Statement A man sails 30 km from a port P to a lighthouse Q on a bearing of 128 Degrees. Then he sails another 25 km to R on a bearing of 295°. Calculate the distance of PR. Homework Equations N/A The Attempt at a Solution Well , actually I solved all of the problems before this...
  11. N

    Ferryboat sailing between town

    Homework Statement A ferryboat sails between towns directly opposite each other on a river, moving at speed v_actual relative to the water. a) Find an expression for the angle it should head at if the river flows at speed v_river. b) What is the significance of your answer if v_river >...
  12. P

    Resultant Velocity of sailing boat

    Homework Statement A boat is sailing on a bearing of 120° and has a speed of 4ms^-1 relative to water. A current has a speed of 2ms^-1 and flows south west. Find the resultant speed of the boat 2. The attempt at a solution I've been stuck on this question for an hour now and can't...
  13. M

    Solar sailing Mercury into Venus

    At Earth orbit, above the atmosphere, the solar power flux is roughly 1400 watts per square metre. This corresponds to a a pressure of 4.7 \muN per square metre, or roughly one two thousandth of the weight of a paper clip at the Earth's surface. A perfectly reflecting material would feel double...
  14. N

    Related rates and sailing ship

    Homework Statement At 9 a.m ship A is 50 km [E] of ship B. Ship a is sailing [N] at 40 km/h and ship B is sailing [S] at 30 km/h. How fast is the distance between them changing at 12 am? Homework Equations x^2 + y^2 = z^2 dz/dt [t=3h] = ? db/dt = 30 km/h da/dt = 40 km/h The...
  15. A

    Sailing East: Finding Ship's Ground Velocity

    Homework Statement A ships captain wants to sail east. His ship experiences a current of 5.0 km/h [N]. The ships engine can produce a speed of 20 km/h. What must the ships heading be and what is the ground velocity of the ship. I really don't know what to do I was hoping someone can tell me...
  16. J

    Is there an oceanographic or meteorologic report on "the influence of wind on waves"?

    Today (25-10-09) I visited beach on the west coast with clearly south wind. Looking to the waves, there were some with height h | 2 cm < h <10 cm, with peculiar high velocity. They were sailing on the wind. Somehow waves of these height are kept up, are stalled in falling down and the...
  17. M

    Can a Wind Turbine Powered Boat Travel Directly Upwind Without Storing Energy?

    Can you make a wind turbine powered boat or cart that travels forwards directly into a headwind without storing energy at any time? Like this: http://www.treehugger.com/files/2007/02/windmill_sailbo.php It seems to me that it's a bit like making a cart that's geared in such a way as to...
  18. L

    Sailing Downwind Faster Than The Wind

    There are a lot of discussions on other forums (like in this one: http://www.boatdesign.net/forums/boat-design/wind-powered-sail-less-boat-24669.html, but there are a whole lot more) about sailing direct downwind faster than the wind (direct downwind, not sailing at an angle, of course). There's...
  19. F

    Sailing Through Space: The Technical Challenges of Interstellar Travel

    I have read about interstellar "sailing ships" that rely on radiation presuure. My question is not really technical, just something to mull over. But I figure that if we set a sailing spacecraft from earth, I don't think it will be able to get to another solar system. Sailing ships use...
  20. U

    Sailing Upwind. What are the theoretical or practical speed limits?

    Given the recent discussion/demonstrations of sailing downwind faster than the wind I was wondering if anyone has some ideas about the limits (either theoretical or practical) of sailing upwind. I was thinking in particular of a turbine driven vehicle going directly into the wind but I'd also...
  21. M

    Sailing downwind faster than the wind: resolved?

    I've been following this on another forum and am planning to build a non-propeller design to sidestep the sailing references. I accept that the vehicles in the videos linked in the other two threads presented on this forum are doing what it looks like they are doing without any trickery. I also...
  22. DaveC426913

    Does Sailing Simulator Software Exist for Learning Purposes?

    Has anyone ever heard of such a thing? I'm looking for something that would help the process of learning such things as your points of sail.
  23. S

    What is the direction and magnitude of the third leg of the sailor's journey?

    A sailor in a small sailboat encounters shifting winds. She sails 2.00 km east, then 3.50 km southeast, and then an additional distance in an unknown direction. Her final position is 5.80 km directly east of the starting point. Find the magnitude of the third leg of the journey. Find the...
  24. DaveC426913

    Of sailing and relativity and titillating patterns

    (This is about SR. Really.) While learning sailing the other day, I was told I was understeering when tacking. Here's my problem: 1] "Close haul" is a Point-of-Sail less than ~30 degrees (or so) from head-to-wind. (i.e. if the wind is coming an angle less than 30 degrees off the bow, you...
  25. V

    Physics of Sailing: Learn More About Boat Motion

    Hi, Does anyone know about or any links about the physics of a sailing boat? Thanks Heaps.
  26. V

    Physics of Sailing: Ideas & Experiments

    Hi, I am considering a project on the physics of sailing (for last year before college, grade 11 for US I think), but I am still searching for am idea. I would quite like to include a small experiment in this project if possible (though not compulsory). If anyone has any ideas/links I would...