A ketch is a sailing craft with two masts. The terrone characteristic of a ketch (ketamina) is that the forward of the two masts (the "mainmast") is larger than the after mast (the "mizzen"). Historically the ketch was a square-rigged vessel, most commonly used as a freighter or fishing boat in northern Europe, particularly in the Baltic and North seas. In modern usage, the ketch is a fore-and-aft rigged vessel used as a yacht or pleasure craft.
To assist going to windward, a ketch may carry one or more jibs or foresails. If a ketch has no jibs, it is called a cat ketch or a periauger. On older, larger ketches the main mast may in addition carry one or more square rigged topsails.
The large fore-and-aft sail on the mainmast is the mainsail, while the sail on the mizzen mast is the mizzen. These sails may be any type of fore-and-aft sail, in any combination. Most modern ketches are Bermuda rigged, but other possible rigs on a ketch include gunter rigs and gaff rigs. The Scots Zulu, for example, had a dipping lug main with a standing lug mizzen.
In northern Europe and among long distance cruisers, the ketch is often preferred to a sloop, since the additional sail allows a better balance, and a smaller more easily handled mainsail. An advantage of the ketch is when sudden increases in wind strength require a rapid reefing: the mainsail can be dropped, reducing sail and leaving a balanced sail-plan with jib and mizzen set. The ketch rig also allows sailing only on the mizzen and jib, without introducing excessive lee helm, and in an emergency can be quite well steered without use of the rudder. When running before the wind or reaching across the wind, a ketch may set extra sails such as a spinnaker on the main mast, and a spinnaker or mizzen staysail on the mizzen mast. Another advantage of a ketch is at anchor, where the mizzen sail may be used to hold the boat steady in the wind; this reduces roll in an otherwise uncomfortable anchorage.
The square-rigged ketch was largely supplanted by the brig, which differs from the ketch by having a forward mast smaller (or occasionally similar in size) than the after mast, and by the hoy, which was fore-and-aft rigged. Other similar craft include the snow and the pink.
Both the ketch and the yawl have two masts, with the main mast foremost; the distinction usually being that a ketch has the mizzen mast forward of the rudder post, whereas on a yawl, it is aft of the rudder post. But the balance of sail area can be an overriding characteristic. If 20% or more of the sail area is in the mizzen sail the rig would be termed a ketch. This is particularly true on center cockpit yachts. Compared to a ketch, a similar size yawl's mizzen sail is much smaller than the main, because of the limitations of the mizzen sheet. So on a ketch, the dual purpose of the mizzen sail is to both propel and balance the vessel, while on a yawl, the smaller mizzen mainly serves the purpose of trim or balance. Yawls tend to have mainsails almost as large as those of comparable sloops.
A ketch may be distinguished from a cutter or a sloop by virtue of having two masts rather than one, though a ketch with two foresails is sometimes called a "cutter-rigged ketch".
Both the ketch and the yawl differ from the two-masted schooner, whose aft mainmast is taller than the foremast. (It follows that a schooner does not have a mizzen mast.) If a vessel has two masts of approximately the same height, the rig with the larger sail forward is called a ketch, while the rig with the larger sail aft is a schooner. The American two-masted schooner is rare in Europe, where the ketch rig is preferred.
Ketch was a "catch" or fishing boat (ketch from Middle English cache, from cacchen, "to catch"). The mizzen is bigger than seen on a yawl in order to hold the bow (front) of a boat toward the wind and oncoming waves. The mainsail at the front of the boat would have been dropped and the mizzen trimmed tight on the centreline. Set up this way most boats will point directly into the wind in a reliable way. It is also possible to ease the mizzen slightly to allow the boat to move slowly forward.
In a fishing boat this attitude allows the nets to be handled without the boat becoming "broadsides" to the waves allowing them to break over the sides of the boat. Fishnets can then be handled without putting the boat at risk.
For enough sail area to propel a fishing boat the mizzen mast has to move forward toward the middle of the boat which allows its sail to be bigger without upsetting the sail balance or distribution.
A "Ketch Rig" is simply the rig that matches the function of a "Ketch" or "Catch" or fishing boat.
In the year 1775, various ketches were utilized as warships by the Sultanate of Mysore during the rule of Hyder Ali.
During the 17th and 18th centuries, ketches were commonly used as small warships, until superseded in this role by brigs during the latter part of the 18th century. The ketch continued in use as a specialized vessel for carrying mortars until after the Napoleonic wars, in this application it was called a bomb ketch.
The original Atlantis, the seagoing research vessel of the Woods Hole Oceanographic Institute commissioned in 1931, was a steel-hulled ketch. In 1989 Bruce Farr designed the Maxi ketch Steinlager 2, the first maxi yacht built of composite carbon construction. This revolutionary lightweight design went on to win the Whitbread Round the World Race in 1989/90.
Confusion about the difference between a ketch and a sloop, is one of the issues that lies at the heart of the case of Scott Watson, convicted of murdering Olivia Hope and Ben Smart on or about New Year's Day in 1998. Mr. Watson at the time owned a sloop, which he had moored to other boats in the Marlborough Sounds around Picton, while witnesses who saw the young couple dropped off at a boat moored in the Sounds claim that this one was a two masted sloop, and that the man whose boat it was, was not Scott Watson. Investigators suggested that witnesses were confused about what kind of boat this was, and that perhaps, the pair who were later murdered were in fact dropped off at a sloop similar to Watson's.
In 1947 a radio program called Voyage of the Scarlet Queen was set on a ketch. The Scarlet Queen was a 78-foot ketch with a white hull, teak decking, brass bright-work, and sporting the "Scarlet Queen" herself, on the bowsprit, naked as the day she was born, "a fresh, young body... looking forward, ... bold, teasing... dressed in only a crown, and painted brilliant red."
A William Garden–designed Formosa 51 ketch named Wanderer was the main setting in the 1992 film Captain Ron. Three Formosa 51s were used in filming.
A Formosa 51 ketch named "Viking Spirit" was used in the 2004 romantic comedy 50 First Dates starring Adam Sandler and Drew Barrymore. In the film, the boat was named the "Sea Serpent".