Editing Daggerboard (section)

==General==
A daggerboard is a removable vertical keel that is inserted through a "trunk" in the center of a vessel's hull, usually amidships. Daggerboards are usually found in small sailing craft such as [[day sailer]]s, which are easily handled by a single person. Daggerboards are not usually ballasted but are locked in place by a clip or pin. Unlike a centreboard, which can be set at different angles to the hull of the boat, daggerboards are generally limited to a single perpendicular position relative to the hull. If a daggerboard is located off center, it is called a [[leeboard]] or a [[bilgeboard]]. 

The characteristic which differentiates daggerboards from other centerboards and [[swing keels]] is that daggerboards are easily removable, even when the boat is underway. [[Centerboard]]s and swing keels, common alternatives to fixed keels, can pivot up and down but are fixed to the hull. The freedom of movement of dagger- and centerboards allows them to swing or slide up into the hull of the boat, which is advantageous when sailing in shallow waters. The pivoting centerboard or swing keel can swing up when it strikes an object which helps prevents the sort of damage to which fixed [[keel]]s or daggerboards are subject.<ref name="Hankinson"/> Daggerboards can be raised and lowered as needed but will generally be damaged if not retracted before impact with the bottom or with floating objects.  

Many small sailboats use a daggerboard instead of a fixed keel. This allows these boats to be more easily moved on trailers, sailed in shallow waters, and easily beached.<ref name="AP2008"/> Daggerboards also afford an opportunity to reduce drag when racing because they can be retracted when not needed (i.e. when sailing downwind or in very light winds). 

[[File:Catamaran.svg|thumb|Catamarans are stable because of their multihull designs which utilize daggerboards.]] [[File:Parts of the rig.JPG|thumb|Keel is vertically removable]]

Daggerboards are often made of wood; the problem with wood is that wood rots over time. Alternate materials for daggerboards are metal (aluminum/steel) and [[fiberglass]]. A daggerboard boat can be costly to manufacture. If not well-made, the daggerboard will transfer vibrations from the trunk through the hull.  

===Purpose===
The purpose of the daggerboard (or any keel) is to balance the force of the wind on the sails. Without a daggerboard or keel, a sailboat could not sail up-wind and would simply be blown sideways.<ref name="Hankinson">Hankinson, K. (1973). Rigging small sailboats. Bellflower, Calif.: Glen-L. Keel daggerboard rudder. (n.d.). Retrieved March 22, 2015, from http://www.mecaflux.com/en/keel{{Dead link|date=July 2019 |bot=InternetArchiveBot |fix-attempted=yes }} daggerboard rudder.htm</ref> 

During a storm, daggerboards can help reduce the tendency of a small boat to tip over ("breach") due to waves. A catamaran in a storm would lift the [[leeward]] hull daggerboard and fully extend the upwind daggerboard.{{Citation needed|date=January 2020|reason=Conventional wisdom, but is there any research on the topic?}} If there is no wind and an outboard motor is being used, lifting the daggerboards will ensure the least drag.<ref>Multihull Keels and Daggerboards | Catamaran Dealer. (2009, March 12). Retrieved April 8, 2015, from http://www.aeroyacht.com/2009/03/12/multihull-keels-and-daggerboards/ {{Webarchive|url=https://web.archive.org/web/20150103224025/http://www.aeroyacht.com/2009/03/12/multihull-keels-and-daggerboards/ |date=2015-01-03 }})</ref>

When a small sailboat flips on its side, the keel can also be used to right the boat. Standing on the keel gives the sailor additional leverage to roll the hull upright. The centerboard, daggerboard, or bilgeboard can be used as a platform upon which to stand, providing increased [[Mechanical advantage|leverage]], in the event the [[Dinghy sailing|dinghy]] overturns via a [[Capsizing|capsize]] or [[Turtling (sailing)|turtle]].

===How it works===
Because water is denser than air, the force generated by wind against the much larger surface area of the sails can be equalized by the force of a relatively small daggerboard pushing in the water below the hull. A daggerboard fits into a trunk that runs through the hull of the rig. When the board is in the trunk it keeps the water out while in use due to how tightly wedged it is. It is held in place by a pin on the forward end or a shock cord. The daggerboard puts a counterforce from the wind pushing on the sails. Daggerboards are often long and thin to reduce drag and increase effective lift, thus providing a better lift-to-drag ratio. 

===History===
In 2008, a {{convert|55|ft|m|adj=mid|-long}} daggerboard ship was found using deep scan sonar equipment off the southern shore of [[Lake Ontario]], the only such vessel known to have been found in the [[Great Lakes]]. Vessels of this type were used for a short time in the early 19th century.<ref name="AP2008">{{cite news|title=Upstate NY explorers ID rare boat in Lake Ontario |date=December 13, 2008 |agency=Associated Press |url=http://www.gmanetwork.com/news/story/139261/news/world/upstate-ny-explorers-id-rare-boat-in-lake-ontario/ |archive-url=https://archive.today/20130124100410/http://www.gmanetwork.com/news/story/139261/news/world/upstate-ny-explorers-id-rare-boat-in-lake-ontario/ |url-status=dead |archive-date=January 24, 2013 }}</ref>

In the early 19th century daggerboards were infrequently being used on American [[schooner]]s. These schooners were used for nearby coastal trade of cotton, wheat, and apples. A sunken 1833 daggerboard schooner was found in the great lakes with the help of sonar equipment.<ref>The Blade. Retrieved April 7, 2015, from http://www.toledoblade.com/local/2014/09/08/Rare-dagger-board-schooner-discovered-in-deep-water-off-Oswego-N-Y.html</ref> Knowing this, daggerboards have been around since late in the 17th century. Daggerboards can be found on [[monohulls]] which is the classic sailboat and [[multihulls]] called catamarans. 

Daggerboards come in all different shapes and sizes, some curved or s-shaped. Curved daggerboards started to appear thirty to forty years ago. The first prototype was made in 1985 by Ian Farrier. The benefits of vertical lift generated by curved daggerboards are nominal. When actually sailing, curved daggerboards - not to be confused with hydrofoils - do not make a drastic change.<ref>(Boat Builder)</ref>