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The junk rig, also known as the Chinese lugsail or sampan rig, is a type of sail rig in which rigid members, called battens, span the full width of the sail and extend the sail forward of the mast.
While relatively uncommon in use among modern production sailboats, the rig's potential advantages of easier use and lower cost for blue-water cruisers have been explored by individuals such as trans-Atlantic racer Herbert "Blondie" Hasler and author Annie Hill.
An origin of the name junk rig is not directly recorded, but it is popularly attributed to the name from the traditional Chinese junk ship, where the rig was in use when first encountered by Europeans. Paul Johnstone and George Hourani, however, attributes the invention of this type of sail to Malay from Island Southeast Asia. They were originally made from woven mats reinforced with bamboo, from at least several hundred years BCE. They were adopted by the Chinese after contact with Malay traders (K'un-lun po) by the time of the Han dynasty (206 BCE to 220 CE). However, the Chinese vessels during this era were essentially fluvial (riverine), they did not build true ocean-going fleets until the 10th century Song dynasty.
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The junk rig is a simple and effective rig. The rig contrasts starkly with the Bermuda rig which is prevalent on Western sail boats. In its most traditional form the junk rig is carried on an unstayed mast (i.e. a mast without shrouds or stays, supported only on the step at the keelson and the partners); however, standing rigging of some kind is not uncommon.
The cost to rig a boat with a junk rig would typically be a fraction of the cost of a Bermuda rig, due mostly to the lower number of parts and adaptability of the rig to cheaper materials (especially the sailcloth.)
The junk rig typically produces less drive than a similarly sized Bermuda rig at low angles of attack (e.g. when sailing upwind, close-hauled) and this is especially pronounced in light wind. Performance close-hauled is perhaps the strong point of the Bermuda rig -- key to winning a race with an upwind leg or outmaneuvering an opponent in battle.
The junk rig typically produces more drive than a similarly sized Bermuda rig when running downwind without a spinnaker. A junk-rigged boat can let its sails out athwartships (and beyond). On a Bermuda-rigged boat the shrouds interfere with sails if the sail was let out until it was athwartship. The full battens of a junk sail prevent the sail from collapsing when running in light wind (dispensing with the need for a whisker pole.) On double-masted junk-rigged boats, the sails can be flown wing-and-wing (i.e. on opposite sides of the boat), even when on a broad reach, as can a Bermudan rig. The junk rig is well suited to downwind travel with its working sails.
The junk rig appeals to shorthanded sailing crews for many reasons, especially because the rig reefs very easily. To lessen sail ("reef") all that is required is to let out the halyard. In contrast, reefing sail on a Bermuda-rigged boat would typically require crew to move about the deck, which increases the chance of falling overboard, especially during a high-sea state which is typical of conditions which would encourage reefing.
It is typical to run the halyards (lines used to raise and lower the sail) and sheets (lines used to trim the sail) to the companionway on a junk-rigged boat. This means that typical sailhandling can be performed from the relative safety of the cockpit, or even while the crew is below deck.
Junk sails are typically carried on a mast which rakes (slants) forward a few degrees from vertical. The forward rake of the sail encourages the sail to swing out, which makes the use of a preventer unnecessary. Another way to say this is that the sail is stable when swung out and doesn't return to the middle of the ship when the wind drops.
Other benefits of the junk rig over the Bermuda rig include:
Other shortcomings of the junk rig compared to the Bermuda rig include:
There are several ships in Island Southeast Asia that use junk rigs with local hulls instead of the Chinese junk hull, they include:
Among the ships used on the coast of China:
Each of the traditional sailing rigs can be achieved using the modern junk sail.
The junk sail is a low tech approach to sailing and requires only inexpensive components. Spars are typically of wood. Lines for running rigging are typically 3-strand cordage rather than dual core braid. The sailcloth materials are typically light canvas or tarpaulin, used Dacron from discarded sails, or even PVC sheeting.
The junk sail is composed of the following components:
The junk sail has essentially the same sides and corner names as the traditional gaff rigged 4-corner sail. Knowing the names of the sides and corners help understand the running rigging and sail trim of the modern junk sail.
The 4 corners of the junk sail are:
The 4 sides of the junk sail are:
The running rigging for the modern junk rig can be divided into two groups--the "pull ups" and the "pull downs." This is important because the action of hauling one line in a group will be resisted by the opposite group. For example, when raising the sail via the halyard, the pull-downs must be uncleated and free to run.
The running rigging which pulls up the junk sail are:
The running rigging which pulls down on the junk sail are:
The running rigging that sets or trims the junk sail (controls the angle of attack relative to the direction of the wind) is the sheet. On a traditional Chinese junk rig, the sail is controlled by sheetlets--small sheet lines running from the battens to blocks that in turn are on lines running through a euphroe, a long piece of wood with holes in it. This helps maintain uniform tension in each panel of the sail. Western ship designers Tom Colvin, Michael Kasten and Herbert "Blondie" Hasler use the same technique, but others (such as Derek Van Loan and Phil Bolger) use a simplified design without euphroes.
Sail handling on the junk rig is ideal for cruising sailors, particularly when sailing short- or single-handed.
There is no need to point "head to wind" when raising sail. When the sheets are sufficiently eased, the junk sail will rotate around the mast to any point of the wind. While sailing dead down wind is inconvenient for making sail, it is still possible to raise the junk sail with the sail luffing.
Raising the junk sail is done by easing the sheets until the furled sail is blown down wind. This will take the pressure off the sail and ease the raising. Then it is important to watch the lines that will run in while the sail is raised, including the gaff hauling parrel, luff hauling parrel, the downhauls if equipped, and the sheets. Hauling the sail with a 3:1 or 4:1 purchase will ease the burden, but the length of halyard will consequently be very long. The fully battened sail will remain calm in the lee of the mast during the hauling. Due to the weight of a huge canvas sail and its many spars, some junk sailors find a winch is needed for the last few feet. There is probably already a standing tack line in place, so the halyard is hauled until the tack line is taut, although there is no need to tighten up the leech severely to avoid scallops as in trimming the triangular sails. After hauling and securing the halyard, the fore and aft position of the leech is set by hauling the yard hauling parrel until the halyard is close to the mast. A short pull on the luff hauling parrel may be needed to extend the middle battens toward the leech to control wrinkles in the sail. The last act is to haul the sheets and set the sail to the wind.
Reefing a junk rigged sail is very easy. When sailing close to the wind, all that is needed is to ease the halyard. As the sail lowers by its own weight, the other running lines will also relax. The sail is lowered until the desired batten is along the boom. Then the gaff hauling parrel and luff hauling parrel are trimmed, and the sheet is hauled to reset the sail to the wind. When reefing on other points of sail, it is helpful to ease the sheet first to take the pressure off the sail, and then ease the halyard and trim the other running lines. When sailing dead down wind, it may be helpful to use a downhaul to reef larger sails.
Emergency furling is fast and simple. When the sheets and halyard are let go, the sail will blow down wind, drop into the cradle of the topping lifts, while being steadied by the full battens. While this is fast and easy, it will also make a mess of the halyards, boom hauling parrel, yard hauling parrel, and downhauls. They will have to be put in order before raising the sail again. For non-emergency furling, it is preferable to drop the sail with two crew so that the slackening lines can be hauled in and maintained in order. Alternatively, a single-handed sailor can lower the sail in stages and attend to the slack lines.
The junk rig brings unique characteristics to each point of sail.
When close hauled, the junk sail rig comes under harsh criticism. In a racer/cruiser world that favors speed and sport, the criticism is quite valid. The junk sail is very inefficient when sailing up wind. The rig cannot "point" as close to the wind, and the craft loses ground by sailing a longer path. In addition, the sails do not generate as much power per square foot of sail area because of the flatness of the sail induced by full battens. In a practical junk rig, this is overcome by having larger sails. However, in a handicap racing situation, this criticism hits an extreme because the handicap is based on sail area: the handicap rating will punish the junk rigged boat severely. On a race course, the buoys are set to assure that the boats will battle directly upwind for half of the race. Thus the junk rigged boat must sail a longer race course to the up wind buoy, at a slower speed, and then is punished by its handicap rating.
In a cruising environment however, sailing up wind is judged differently. Slowing down when beating to windward is sensible cruising. The junk rig is also self tacking. None of the running lines need to be touched to tack the boat through the eye of the wind: one simply puts the helm down, and the sails will swing over close hauled on the new tack.
On the reach, the criticism of the inefficiency of the flat sail shape of the junk sail seems to apply again, but only in very light winds. This can be overcome with cruising spinnaker and gennaker on the junk rig. However, in moderate winds, both the larger inefficient junk sails and the small efficient modern sails will generate sufficient power to drive the hull near its hull speed. In high winds, the flatness of the junk sails is a benefit, where the modern rigged boat will require reefs. In a heavy blow, the ease of reefing will give the junk rig a clear advantage.
When running, the junk sail rig shows its advantage. When cruising, many sailors seek the trade winds and maximize their downwind routes. The huge sail area cross section of the junk rigged sail spreads a powerful wall of canvas far greater than a modern rigged boat, which will require a spinnaker to catch up. The junk rigged boat sails more easily downwind because it is self-jibing (just as self-tacking): just put the helm over to windward, and around she goes without touching anything. The center of effort on the junk sail can be adjusted by sliding the sail forward, exchanging sail area from behind the mast to before the mast: this improves the downwind balance of the sail and tames the jibe. Directly down wind, the junk rigged boat can sail "goose winged" (also known as "wing and wing," or even "wing and wong" by cruising sailors such as Annie Hill) with great ease and success. In this cruising environment, the junk rigged yacht is fast, easy to use, and inexpensive to set up and maintain.
Heaving to in the junk rigged yacht is simple. Simply luff the boat into the wind with the sails close hauled and then put the helm down when the forward speed is spent. The battens will tame the luffing sails. Heaving to in severe weather is done by dropping the forward junk sails into their cradle and reefing the aft junk rigged sails--both tasks that are simplified by the junk rig. Heaving to in light winds can be difficult due to the lack of sail drive up wind.
Bill King sailed the junk schooner (i.e. junk-rigged boat with two masts) Galway Blazer II in the Sunday Times Golden Globe Race.
Joshua Slocum and his family built and sailed a junk-rigged boat Liberdade from Brazil to Washington, DC after the wreck of his barque Aquidneck. Slocum had high praise for the practicality of the junk rig: "Her rig was the Chinese sampan style, which is, I consider, the most convenient boat rig in the whole world."
Kenichi Horie sailed across the Pacific Ocean in 1999 aboard a 32.8-foot (10.0 m) long, 17.4-foot (5.3 m) wide, catamaran constructed from 528 beer kegs. The rigging consisted of two side-by-side masts with junk rig sails made from recycled plastic bottles.