thumb|upright=1.0|Amante, a 1983 "Choate 48" in Newport Beach, California, in February 2015 flying a symmetric spinnaker
thumb|Bear of Britain, a [[Farr Yacht Design|Farr 52 with masthead spinnaker in front of Calshot Spit]]
A spinnaker is a sail designed specifically for sailing off the wind on courses between a reach (wind at 90° to the course) to downwind (course in the same direction as the wind). Spinnakers are constructed of lightweight fabric, usually nylon, and are often brightly colored. They may be designed to perform best as either a reaching or a running spinnaker, by the shaping of the panels and seams. They are attached at only three points and said to be flown.
Etymology
Some dictionaries suggest that the origin of the word could be traced to the first boat to commonly fly a spinnaker, a yacht called Sphinx, mispronounced as Spinx. Sphinx first set her spinnaker in the Solent in 1865, and the first recorded use of the word was in 1866 in the August edition of Yachting Calendar and Review (p. 84). In addition, the term may have been influenced by the spanker, originally a gaff rigged fore-and-aft sail.
Another suggestion is that the idea for the sail was conceived in 1865 by William Gordon, owner of the racing yacht Niobe. He wanted to name the sail after his yacht but a crewman's comment, "Now there's a sail to make her spin" became "spin maker" which developed into the commonly accepted term spinnaker. Gordon was widely known in the yachting world of the time as "Spinnaker Gordon".
It has been pointed out, however, that the skippers of Thames sailing barges also used the term spinnaker for their jib staysails. Unlike the other, tanned sails of these boats, the spinnakers were usually white. It has thus been suggested that the term could be "connected with the obsolete word spoon, meaning to run before the wind (cf. spindrift)." Early usage of the verb to spoon can be traced back to the 16th century; the change from spoon to spin in the term spindrift is attributed to a local Scottish pronunciation. According to Merriam Webster's dictionary, however, spindrift derives from a local Scottish pronunciation of speen (not spoon), meaning "to drive before a strong wind."
According to Merriam-Webster's etymology, the origin of the word spinnaker is simply unknown.
Types
There are two main categories of spinnakers, symmetric and asymmetric depending on whether a plane of symmetry exists for that particular sail. Asymmetric spinnakers operate more like a jib, generating lift from the side, rather than the top like a symmetric spinnaker. This makes asymmetrics a better choice on reaching courses than symmetric spinnakers, which excel when running. While a fully equipped racing boat might have a number of spinnakers, both symmetric and asymmetric, to cover all courses and wind conditions, cruising boats almost always use an asymmetric, due to the broader application and easier handling afforded by the asymmetric.
Symmetric
thumb|[[420 (dinghy)|420 class dinghies with symmetric spinnakers.]]
The symmetric one is the most classic type, running symmetrically alongside the boat controlled by lines known as a sheet and a guy running from the lower two corners of the sail. The windward line, or guy, is attached to the corner called the tack of the sail, and is stabilized by a spinnaker pole. The leeward (downwind) line is called the sheet. It attaches to the clew of the spinnaker and is used to control the shape of the sail. The spinnaker pole must be moved in each gybe, and is quite difficult for beginners to use. However, it can be sailed in all downwind wind directions.
Asymmetric
thumb|RS K6 keelboat with an asymmetric spinnaker on a retracting [[bowsprit.]]
Asymmetrical spinnakers resembling large jibs and flown from spinnaker poles are not a new idea and date back to at least the 19th century. However, in the 1980s a new concept appeared, starting with the Sydney Harbour 18ft Skiff fleet.
Since the 1960s, many faster sailing craft, starting with catamaran classes, have discovered that it is faster to sail downwind on a series of broad reaches with efficient airflow across the sail rather than directly downwind with the sails stalled. This technique had developed to the extent that in bar conversation at the end of one season Andrew Buckland observed that the 18s had sailed all season without pulling the spinnaker pole back from the forestay and that all the systems could be simplified by eliminating the pole and setting the spinnaker from a fixed (but often retractable) bowsprit. The concept quickly evolved to a sail with a loose luff much more like a conventional spinnaker than the old jib-style asymmetric sails. Julian Bethwaite was the first to rig and sail a boat with one the next season, followed shortly by Andrew Buckland. The first modern offshore sailboats to incorporate a retractable bow sprit and an asymmetric spinnaker was the J/Boats J/105.
The concept has spread rapidly through the sailing world. The tack of the sail may be attached at the bow like a genoa but is frequently mounted on a bowsprit, often a retracting one. If the spinnaker is mounted to a special bowsprit, it is often possible to fly the spinnaker and the jib at the same time; if not, then the spinnaker will be shadowed by the jib, and the jib should be furled when the spinnaker is in use.
The asymmetric has two sheets, very much like a jib, but is not attached to the forestay along the length of the luff, but only at the corners. Unlike a symmetric spinnaker, the asymmetric does not require a spinnaker pole, since it is fixed to the bow or bowsprit. The asymmetric is very easy to gybe since it only requires releasing one sheet and pulling in the other one, passing the sail in front of the forestay. Asymmetrics are less suited to sailing directly downwind than spinnakers, and so instead the boat will often sail a zig-zag course downwind, gybing at the corners. An asymmetric spinnaker is particularly effective on fast planing dinghies as their speed generates an apparent wind on the bow allowing them to sail more directly downwind. It is also particularly useful in cruising yachts in the form of a cruising spinnaker or cruising chute, where the ease of handling is important.
Cruising
A cruising chute is a form of asymmetric spinnaker used by cruising yachts and designed for easy use when short-handed. Two sheets are used, with the tack line eased by a foot or so before gybing. Alternatively, only one sheet is used, with the sail snuffed before a gybe.
Code Zero
A Code Zero is a light-weight sail that approaches the dimensions of a genoa jib, for light airs and points of sail up to a close reach. It may be launched furled on its own stay. and asymmetric sails.
- Code 1 is a light air reaching sail, where the apparent wind angles at low speeds has a significant effect to create angles of less than 90 degrees.
- Code 2 is a medium air running sail, used for apparent wind angles over 90 degrees.
- Code 3 is a medium air reaching sail, used for apparent wind angles near 90 degrees.
- Code 4 is a heavy air running sail, used in the heaviest winds normally expected.
- Code 5 is a heavy air reaching sail, used in the heaviest winds normally expected.
- Code 6 is a storm sail, for running in storm conditions.
Setting the sail
thumb|Aigue Blu raising her spinnaker during the Corsica Classic 2013 yacht race
Since they will only be used on certain points of sail, raising and lowering the spinnaker is a task that is often performed while under sail. Due to the size of spinnakers (the spinnaker is often double or more the size of the mainsail) this can be a difficult operation, since the sail will immediately catch the wind.
Symmetric
Typically the symmetric spinnaker is packed in its own bag, called a turtle, with the three corners on top for ready access. The clews (lower corners) are controlled by lines called sheets. The sheets are run in front (outside) of the forestay and lead to the back of the boat. The head (top corner) is attached to the spinnaker halyard, which is used to raise the sail up the mast. On racing boats, the tack of the asymmetric is often rigged to a retractable bowsprit, which increases the foretriangle area and prevents interference with the jib. As this trend becomes more popular in racing boats, it may result in similar adaptations to cruising boats as well.<!--Presenting a single commercial website of a boatbuilder adding this feature dies not support this speculation about this trend in boat design. I do not disagree that it is true. I disagree that WP editors are to speculate on sport equipment design trends, but rather are to quote experts as they state their **published, peer-reviewed** opinions.-->
Jibing with the asymmetric is much less complex than the symmetric, due to the lack of the spinnaker pole. Much like a jib, all that is required is to change sheets; however, since the asymmetric still flies in front of the forestay, the operation is reversed. The loaded sheet is slackened, and the opposite (lazy) sheet is pulled in, which allows the sail to pass around in front of the forestay, and then be sheeted in on the new lee side of the boat.
Retrieving the asymmetric is similar to the process for the symmetric. The sheets are released, allowing the sail to collapse to the front of the boat. The foot of the sail is then gathered, the halyard released and the head of the sail lowered, where it is packed into the turtle.
The spinnaker is raised as normal, but with the sock in place, the spinnaker is unable to catch the wind. Once the spinnaker is raised and the guys are ready to set, the sock is raised, releasing the spinnaker. The sock remains bundled up at the head of the sail while the spinnaker is deployed. To retrieve the spinnaker, the sheet or the tack is released and the sock is pulled down, gathering the sail. The halyard is then dropped and the sail may be packed away. One system focuses on the launching of the spinnaker, only, and it makes use of special sail-packing and a funnel system that places breakable elastic bands as the sail is launched, bands that break as sheet and guy of the filled spinnaker are trimmed. which also stores the sail, which after launching (sock hoisting) is rigged such that the sock's top ring is toward the halyard and bottom ring toward the deck, where release of the spinnaker is accomplished by rigging that draws the bottom ring toward the halyard, allowing the bottom of the sail to fill, a design that leaves the collapsed sock aloft "at the head of the spinnaker while it is flying". and updated older classes, it often consists of a tube or an aperture mounted on the deck close to the forestay. To allow recovery of the spinnaker into the chute during dousing, the spinnaker is fitted with one or more recovery patches to, or through which, the tail of the spinnaker halyard is attached or passed; the spinnaker head and its halyard form a continuous loop, passing through the chute. If a watertight arrangement is not required, a cloth tube may be used to contain the lowered spinnaker.