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Sailing

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For other uses, see Sailing (disambiguation).
Wooden sailing boat

Sailing is the art of controlling a boat with large (usually fabric) foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to change the direction and speed of a boat. Mastery of the skill requires experience in varying wind and sea conditions, as well as knowledge concerning sailboats themselves.

While there are still some places in Africa and Asia where sail-powered fishing or transport vessels are used, these craft have become rarer, as outboard and modified car engines have become available even in the poorest and most remote areas. In most countries people enjoy sailing as a recreational activity. Recreational sailing or yachting can be divided into racing and cruising. Cruising includes extended trips, short trips within sight of land, and daysailing.

History

Throughout history sailing has been instrumental in the development of civilization, affording mankind greater mobility and capacity for fishing, trade, and warfare. The earliest representation of a ship under sail appears on a painted disc found in Kuwait dating to the late 5th millennium BC.[1] Advances in sailing technology from the Middle Ages onward enabled Arab, Chinese, Indian and European explorers to make longer voyages into regions with extreme weather and climatic conditions. There were improvements in sails, masts and rigging; navigation equipment improved. From the 15th century onwards, European ships went further north, stayed longer on the Grand Banks and in the Gulf of St. Lawrence, and eventually began to explore the Pacific Northwest and the Western Arctic.[2] Sailing has contributed to many great explorations in the world.

Physics

Introduction

A sailing vessel moves forward because of the reaction of moving air on its sails.

Energy capture

The energy that drives a sailboat is harnessed by manipulating the relative movement of wind and water speed: if there is no difference in movement, such as on a calm day or when the wind and water current are moving in the same direction at the same speed, there is no energy to be extracted and the sailboat will not be able to do anything but drift. Where there is a difference in motion, then there is energy to be extracted at the interface. The sailboat does this by placing the sail(s) in the air and the hull(s) in the water.

Sails are airfoils that work by using an airflow set up by the wind and the motion of the boat. The combination of the two is the apparent wind, which is the relative velocity of the wind relative to the boat's motion. The sails generate lift using the air that flows around them. The air flowing at the sail surface is not the true wind.[3] Sailing into the wind causes the apparent wind to be greater than the true wind and the direction of the apparent wind will be forward[4] of the true wind. Some high-performance boats are capable of traveling faster than the true windspeed on some points of sail, see for example the Hydroptère, which set a world speed record in 2009 by sailing 1.71 times the speed of the wind.[5][6] Iceboats can typically sail at 5 times the speed of the wind.[7]

The sail alone is not sufficient to drive the boat in any desired direction. Sailboats overcome this by having another physical object below the water line. This may take the form of a keel, centerboard, or some other form of underwater foil, or even the hull itself (as in catamarans without centreboard or in a traditional proa). Thus, the physical portion of the boat that is below water can be regarded as functioning as a "second sail". Having two surfaces against the wind and water enables the sailor to travel in almost any direction and to generate an additional source of lift from the water. The flow of water over the underwater hull portions creates a hydrodynamic force. The combination of the aerodynamic force from the sails and the hydrodynamic force from the underwater hull section allows motion in almost any direction except straight into the wind.[8] This can be likened, in simple terms, to squeezing a wet bar of soap with two hands, causing it to shoot out in a direction perpendicular to both opposing forces. Depending on the efficiency of the rig, the angle of travel relative to the true wind can be as little as 35° or greater than 80°. This angle is called the tacking angle [4].

Tacking is essential when sailing upwind. The sails, when correctly adjusted, will generate aerodynamic lift. When sailing downwind, the sails no longer generate aerodynamic lift and airflow is stalled, with the wind push on the sails giving drag only. As the boat is going downwind, the apparent wind is less than the true wind and this, allied to the fact that the sails are not producing aerodynamic lift, serves to limit the downwind speed.[9]

Some non-traditional rigs purportedly capture energy from the wind in a different fashion and are capable of feats that traditional rigs are not, such as sailing directly into the wind. One such example is the wind turbine boat, also called the windmill boat [5], which uses a large windmill to extract energy from the wind, and a propeller to convert this energy to forward motion of the hull. A similar design, called the autogyro boat, uses a wind turbine without the propellor, and functions in a manner similar to a normal sail [6].

Effects of wind shear

Wind shear affects sailboats in motion by presenting a different wind speed and direction at different heights along the mast. Wind shear occurs because of friction above a water surface slowing the flow of air. Thus, a difference in true wind creates a different apparent wind at different heights. Sailmakers may introduce sail twist in the design of the sail, where the head of the sail is set at a different angle of attack from the foot of the sail in order to change the lift distribution with height. The effect of wind shear can be factored into the selection of twist in the sail design, but this can be difficult to predict since wind shear may vary widely in different weather conditions. Sailors may also adjust the trim of the sail to account for wind gradient, for example, using a boom vang.[10]

Points of sail

Further information: Points of sail
The points of sail. A. In Irons (into the wind) B. Close Hauled C. Beam Reach D. Broad Reach E. Running

The points of sail are the most important parts of sail theory to remember. The no-go zone is about 45° either side of the true wind for a racing hull and sail plan optimized for upwind work. On some cruising yachts, the best course achievable upwind is 50° to 55° to the true wind. No sailboat can sail directly into the wind; attempting to do so leads to the sails luffing. There are 5 main points of sail. In order from the edge of the no-go zone to directly downwind they are:

  • close haul (often about 45° to the apparent wind - the least angle that the boat and its rig can manage)
  • close reach (between close hauled and a beam reach)
  • beam reach (90° to the apparent wind)
  • broad reach (between a beam reach and running)
  • running (close to directly downwind)

The sail trim (and, on smaller boats, centre board/dagger board position) on a boat is relative to the point of sail one is on: on a beam reach sails are mostly let out, on a run sails are all the way out, and close hauled sails are pulled in very tightly. Two main skills of sailing are trimming the sails correctly for the direction and strength of the wind, and maintaining a course relative to the wind that suits the sails once trimmed.

Beating or "working"

Using a series of close-hauled legs to beat a course upwind.

A boat can only get to an upwind destination by sailing close-hauled with the wind coming from one side, then tacking (turning the boat through the eye of the wind) and sailing with the wind coming from the other side. By this method of zig-zagging into the wind it is possible to reach any upwind destination.[8] A yacht beating to a mark directly upwind one mile away will cover a distance through the water of at least 1.4 miles, if it can tack through an angle of 90 degrees with negligible leeway. An old adage describes beating as sailing for twice[11] the distance at half the speed and three times the discomfort.

How closely a boat can sail into the wind depends on the boat's design, sail shape and trim, the sea state, and the wind speed.

Typical angles to the true wind are as follows. Actual course over the water will be worse due to leeway.

  • about 35° for modern racing yachts which have been optimized for upwind performance (like America's Cup yachts)
  • about 42 to 45° for modern cruiser-racer yachts (fast cruising yachts)
  • about 50 to 60° for cruisers with an emphasis on interior space, ease of handling and often low draught rather than sailing performance, and for boats carrying two or more masts (since the forward sails adversely affect the aft sails when sailing upwind)
  • close to 90° for square riggers and similar vessels due to the sail shape which is very ineffective when sailing upwind

Reaching

When the boat is traveling approximately perpendicular to the wind, this is called reaching. A "beam" reach is with the apparent wind at right angles to the boat, a "close" reach is anywhere between beating and a beam reach, and a "broad" reach is between a beam reach and running.

For most modern sailboats, that is boats with fore-and-aft sails, reaching is the fastest way to travel. The direction of the wind is ideal when reaching because it can maximize the lift generated on the sails in the forward direction of the boat, giving the best boat speed. Also when reaching, the boat can be steered exactly in the direction that is most desirable, and the sails can be trimmed for that direction.

Reaching may, however, put the boat on a course parallel with the crests of the waves. When the waves are steep, it may be necessary to sail closer to the wind to avoid waves directly on the beam.

Running

A Thistle running downwind with a spinnaker.

Sailing the boat within roughly 30 degrees either side of dead downwind is called a run. This can be the most comfortable point of sail, but requires constant attention. Loss of attention by the helmsman can lead to an accidental jibe, causing injury to the boat or crew. All on deck must be aware of, and if possible avoid, the potential arc of the boom, mainsheet and other gear in case an accidental jibe occurs during a run. A preventer can be rigged to reduce danger and damage from accidental jibes.

In stronger winds, rolling increases as there is less rolling resistance provided by the sails, as they are eased out. In smaller boats, death rolls can build up and lead to capsize.

Any boat over-canvassed on a run can round up, heel excessively and stop suddenly in the water. This is called broaching and it can lead to capsize, possible crew injury and loss of crew into the water.

Options for manoeuvering are also reduced. On other points of sail, it is easy to stop or slow the boat by heading into the wind; there may be no such easy way out when running, especially in close quarters or when a spinnaker, whisker pole or preventer are set.

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Sailing hulls and hull shapes

Further information: Hull (watercraft)
Musto Performance Skiff

Sailing boats with one hull are "monohulls", those with two are "catamarans", those with three are "trimarans". A boat is turned by a rudder, which itself is controlled by a tiller or a wheel, while at the same time adjusting the sheeting angle of the sails. Smaller sailing boats often have a stabilising, raisable, underwater fin called a centreboard (or daggerboard); larger sailing boats have a fixed (or sometimes canting) keel. As a general rule, the former are called dinghies, the latter keelboats. However, up until the adoption of the Racing Rules of Sailing, any vessel racing under sail was considered a yacht, be it a multi-masted ship-rigged vessel (such as a sailing frigate), a sailboard (more commonly referred to as a windsurfer) or remote-controlled boat, or anything in between. (See Dinghy sailing.)

Multihulls use flotation and/or weight positioned away from the centre line of the sailboat to counter the force of the wind. This is in contrast to heavy ballast that can account for up to 90% (in extreme cases like AC boats) of the weight of a monohull sailboat. In the case of a standard catamaran there are two similarly-sized and -shaped slender hulls connected by beams, which are sometimes overlaid by a deck superstructure. Another catamaran variation is the proa. In the case of trimarans, which have an unballasted centre hull similar to a monohull, two smaller amas are situated parallel to the centre hull to resist the sideways force of the wind. The advantage of multihulled sailboats is that they do not suffer the performance penalty of having to carry heavy ballast, and their relatively lesser draft reduces the amount of drag, caused by friction and inertia, when moving through the water.

Types of sails and layouts

Further information: Sailboat
Traditional sailing off the northern coast of Mozambique.

A traditional modern yacht is technically called a "Bermuda sloop" (sometimes a "Bermudan sloop"). A sloop is any boat that has a single mast and a headsail (generally a jib) in addition to the mainsail. The Bermuda designation refers to the fact that the sail, which has its forward edge (the "luff") against the mast (the main sail), is a sail roughly triangular in shape. Additionally, Bermuda sloops only have a single sail behind the mast. Other types of sloops are gaff-rigged sloops and lateen sloops. Gaff-rigged sloops have quadrilateral mainsails with a gaff (a small boom) at their upper edge (the "head" of the sail). Gaff-rigged vessels may also have another sail, called a topsail, above the gaff. Lateen sloops have triangular sails with the upper edge attached to a gaff, and the lower edge attached to the boom, and the boom and gaff are attached to each other via some type of hinge. It is also possible for a sloop to be square rigged (having large square sails like a Napoleonic Wars-era ship of the line). Note that a "sloop of war," in the naval sense, may well have more than one mast, and is not properly a sloop by the modern meaning.

If a boat has two masts, it may be a schooner, a ketch, or a yawl, if it is rigged fore-and-aft on all masts. A schooner may have any number of masts provided the second from the front is the tallest (called the "main mast"). In both a ketch and a yawl, the foremost mast is tallest, and thus the main mast, while the rear mast is shorter, and called the mizzen mast. The difference between a ketch and a yawl is that in a ketch, the mizzen mast is forward of the rudderpost (the axis of rotation for the rudder), while a yawl has its mizzen mast behind the rudderpost. In modern parlance, a brigantine is a vessel whose forward mast is rigged with square sails, while her after mast is rigged fore-and-aft. A brig is a vessel with two masts both rigged square.

As one gets into three or more masts the number of combinations rises and one gets barques, barquentines, and full rigged ships.

A spinnaker is a large, full sail that is only used when sailing off wind either reaching or downwind, to catch the maximum amount of wind.

Sailing by high altitude wind power

SkySails is sailing freighter ships.[12] Speedsailor Dave Culp strongly introduced his OutLeader kite sail for speedsailing.[13] Malcolm Phillips invents an advanced sailing technique using high altitude kites and kytoon.[14]

Rigid foils

With modern techonology, "wings", that is rigid sails, may be used in place of fabric sails. An example of this would be the International C-Class Catamaran Championship and the yacht USA that won the 2010 America's Cup.[15] Such rigid sails are typically made of thin plastic fabric held stretched over a frame.[15]

Sailing terminology

Further information: Glossary of nautical terms

Sailors use traditional nautical terms for the parts of or directions on a vessel; starboard (right), port (left), forward or fore (front), aft (rearward), bow (forward part of the hull), stern (aft part of the hull), beam (the widest part). Vertical spars are masts, horizontal spars are booms (if they can hit the sailor), gaffs (if they are too high to reach) or poles (if they cannot hit the sailor).

Rope and lines

Standing rigging (on the left) and running rigging (on the right), on a sailing boat.

In most cases, rope is the term used only for raw material. Once a section of rope is designated for a particular purpose on a vessel, it generally is called a line, as in outhaul line or dock line. A very thick line is considered a cable. Lines that are attached to sails to control their shapes are called sheets, as in mainsheet. If a rope is made of wire, it maintains its rope name as in 'wire rope' halyard.

Lines (generally steel cables) that support masts are stationary and are collectively known as a vessel's standing rigging, and individually as shrouds or stays. The stay running forward from a mast to the bow is called the forestay or headstay.

Moveable lines that control sails or other equipment are known collectively as a vessel's running rigging. Lines that raise sails are called halyards while those that strike them are called downhauls or cunninghams. Lines that adjust (trim) the sails are called sheets. These are often referred to using the name of the sail they control (such as main sheet, or jib sheet). Sail trim may also be controlled with smaller lines attached to the forward section of a boom; such a line is called a vang, or a kicker in the United Kingdom.

Lines used to tie a boat up when alongside a dock are called docklines, docking cables or mooring warps. In dinghies the single line from the bow is referred to as the painter.

Some lines are referred to as ropes:

  • a bell rope (to ring the bell),
  • a bolt rope (attached to the edge of a sail for extra strength),
  • a foot rope (on old square riggers for the sailors to stand on while reefing or furling the sails), and
  • a tiller rope (to temporarily hold the tiller and keep the boat on course). A rode is what keeps an anchor attached to the boat when the anchor is in use. It may be chain, rope, or a combination of the two.

Other terms

Sailboat on a mooring ball near Youngstown, NY

Walls are called bulkheads or ceilings, while the surfaces referred to as ceilings on land are called 'overheads'. Floors are called 'soles' or decks. The toilet is traditionally called the 'head', the kitchen is the galley. Lines are rarely tied off, they are almost always 'made fast' or 'belayed.' Sails in different sail plans have unchanging names, however. For the naming of sails, see sail-plan.

Knots

Knots are among the most important things a sailor needs to know. Although only a few are required, the bowline in particular is essential. By also learning the clove hitch and "round turn and two half hitches," one can easily cope with all of the knot requirements of a boat. A more complete grasp of knot-tying includes mastery of the following knots:

Additional knots are available List of knots

Even experienced sailors may forget their knots if they are not performed on a regular basis. Forgetting how to tie an important knot can damage a boat or cause injury.

Sailing regulations

There are three basic rules for avoiding a collision at sea, but this is a simplification of a detailed set of regulations:

  1. A yacht using sails as motive power on port tack[16] gives way to one on starboard tack.[17].
  2. The more maneuverable vessel gives way to the less maneuverable vessel. It is generally assumed that this means that power 'gives way' to sail, but this is not always the case. It is prudent for a small sailing vessel to stay out of the way of large power driven ships by making an early and obvious alteration in course to signal both recognition of a potential collision situation and that avoiding action has been taken. It is mandatory, by port and harbour regulations, that sailing vessels shall stay clear of shipping in a buoyed channel.
  3. If a collision is imminent both vessels must take avoiding action even if one vessel (this is the 'stand-on' vessel) would normally take no action. Not to do so, if there is an opportunity, may make the sailor the guilty party at an inquiry. The use of the term 'right of way' is borrowed from yacht racing environment, does not appear in internationally recognised rules for vessels not racing and is inappropriate to all other vessels and situations.

Power driven vessel A that is on a potential collision course crossing the port side of power driven vessel B must give way. Sailing boats with their sails set on the same side of the boat, require that[18] the windward boat shall give way to the leeward boat.[19] Vessel A overtaking vessel B normally must keep clear. Head-on collisions are avoided by the vessels both turning to starboard.

If these rules are not followed in a yacht race, a protest may be called by one of the skippers. A hearing of protestor and protestee by the protest committee panel will decide who wins the rule breach.

However there are many other rules besides these that are applicable, and sailors are required to know these fundamental boating safety rules, including:

  • The "rules of the road" or International Regulations for Preventing Collisions at Sea (COLREGS) set forth by the International Maritime Organization are particularly relevant to sailboats because they may be sharing the same body of water as powered vessels, who are bound by the COLREGS.
  • The IALA International Association of Lighthouse Authorities standards for lateral marks, lights, signals, and buoyage and rules designed to support safe navigation.
  • The SOLAS (Safety of Life at Sea) regulations place the obligations for safety on the owners and operators of any boat including sailboats. These regulations specify the safety equipment needed and emergency procedures to be used appropriate to the boat's size and its sailing range.
  • When racing, all sailing vessels must follow the Racing Rules of Sailing promulgated by the International Sailing Federation as well as any prescriptions (additional rules) given by the national governing body and organisation running the event. When a boat that is racing encounters one that is not, the racing boat must comply with the International Regulations for Preventing Collisions at Sea with respect to the non-racing boat. It is the custom amongst sailors that a sailing boat cruising will not normally get in the way of a racing fleet. Similarly, all sailors give way to divers' boats and fishers for reasons of safety & courtesy.

After sunset all boats racing are bound by the International Regulations for Preventing Collisions at Sea (COLREGS) rather than the Racing Rules of Sailing.

Licensing

Depending on the country or continental union, boating on coastal waters and inland waters may require a license. Usually, boating on inland waters almost always requires a license, while boating on coastal waters only requires a license when a certain boat size is exceeded (e.g., a length of 20 meters), or when passenger ships, ferries or tugboats are steered.[20] Boating on international waters does not require any license, due to the absence of any laws or restrictions in this area. Europe's continental union, the EU, issues the International Certificate of Competence.

Sailboat racing

U.S. Sailing team at the World Military Games Sailing Competition, December 2003

Sailboat racing ranges from single person dinghy racing to large boats with 10 or 20 crew and from small boats costing a few hundred dollars to multi-million dollar America's Cup or Sydney to Hobart Yacht Race campaigns. The costs of participating in the high end large boat competitions make this type of sailing one of the most expensive sports in the world. However, there are inexpensive ways to get involved in sailboat racing, such as at community sailing clubs, classes offered by local recreation organizations and in some inexpensive dinghy and small catamaran classes. Additionally high schools and colleges may offer sailboat racing programs through the Interscholastic Sailing Association (in the USA) and the Intercollegiate Sailing Association (in the USA and some parts of Canada). Under these conditions, sailboat racing can be comparable to or less expensive than sports such as golf and skiing. Sailboat racing is one of the few sports in which people of all ages and genders can regularly compete with and against each other.

Most sailboat and yacht racing is done in coastal or inland waters. However, in terms of endurance and risk to life, ocean races such as the Volvo Ocean Race, the solo VELUX 5 Oceans Race, and the non-stop solo Vendée Globe, rate as some of the most extreme and dangerous sporting events. Not only do participants compete for days with little rest, but an unexpected storm, a single equipment failure, or collision with an ice floe could result in the sailboat being disabled or sunk hundreds or thousands of miles from search and rescue.

The sport of Sailboat racing is governed by the International Sailing Federation (ISAF), and the rules under which competitors race are the Racing Rules of Sailing, which can be found on the ISAF web site.

As well as these there is the "mini transats" in which very small craft and solo sailers cross the Atlantic Ocean. The Vendee Globe is another race for larger boats. Other races include the Fastnet race from Cowes, around the Fastnet rock just off the coast of Ireland and back again to the Plymouth. There is also the Sydney to Hobart race. Another very important race is the Valtur World Cup for Amateurs disputated in Pollina (Italy) in 2001.

See also

Notes

  1. ^ Carter, Robert "Boat remains and maritime trade in the Persian Gulf during the sixth and fifth millennia BC"Antiquity Volume 80 No.307 March 2006 [1]
  2. ^ "Transportation and Maps" in Virtual Vault, the art of the boat is sofa an online exhibition of Canadian historical art at Library and Archives Canada
  3. ^ As would be seen by a wind in relation to the boat which also has a velocity. The curved surface of a sail serves to deflect the air. Deflecting the air results in a reaction force on the sail and rigging, which pushes the boat in a direction opposite to the deflection. It is often said that lift is generated by the pressure differential on the sails, but this is not entirely true--the pressure differential deflects the air, but it is the deflection that generates the force. Since the air behind the sailboat has been deflected, it now has less energy and is slower and is often called dirty air. Racing sailors try to avoid sailing in dirty air and attempt to give dirty air to opponents where possible. A common technique is trying to get upwind of an opponent, and make them sail in your dirty air, slowing them down
  4. ^ Forward of means making a smaller angle relative to the bow than the angle that the true wind makes relative to the bow
  5. ^ http://www.sailspeedrecords.com/index.php?option=com_content&view=article&id=104:wssr-newsletter-no-177-hydroptere-world-records-230909&catid=2:news&Itemid=5
  6. ^ http://www.hydroptere.com/
  7. ^ See "How fast do these things really go?" in the "FAQ published by the Four Lakes Ice Yacht Club".
  8. ^ a b How sail boats sail against the wind? Faster than the wind? http://PhysicsForArchitects.com/Sailing_against_the_wind.php
  9. ^ Large sails of big area, spinnakers serve to increase the sail area for more performance downwind.
  10. ^ Garrett, Ross (1996). The Symmetry of Sailing. Dobbs Ferry: Sheridan House. pp. 97–99. ISBN 1574090003.
  11. ^ Each leg at 45 degrees to the true wind is 0.71miles, but in reality is longer as tacking angles greater than 45 degrees are the norm and leeway is also significant
  12. ^ [2]
  13. ^ [3]
  14. ^ * US Patent 6925949 Elevated sailing apparatus by Malcolm Phillips, filed Dec 31, 2002.
  15. ^ a b http://www.sailmagazine.com/cclasscats/
  16. ^ Sails set for a breeze coming from the left hand side of the boat
  17. ^ Sails set for a breeze coming from the right side of the boat
  18. ^ the boat closer to where the wind is coming from,
  19. ^ Boat further away from the wind
  20. ^ Info from Dutch wikipedia article; Vaarbewijs

Bibliography

  • "Transportation and Maps" in Virtual Vault, an online exhibition of Canadian historical art at Library and Archives Canada

www.sailtube.tv - international Sailing Network

  • Rousmaniere, John, The Annapolis Book of Seamanship, Simon & Shuster, 1999
  • Chapman Book of Piloting (various contributors), Hearst Corporation, 1999
  • Herreshoff, Halsey (consulting editor), The Sailor’s Handbook, Little Brown and Company, 1983
  • Seidman, David, The Complete Sailor, International Marine, 1995
  • Jobson, Gary, Sailing Fundamentals, Simon & Shuster, 1987

External links

Wikimedia Commons has media related to Sailing.
Look up sailing in Wiktionary, the free dictionary.

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