Editing Point of sail (section)

==True wind versus apparent wind==
{{Main|Forces on sails#Effect of points of sail on forces}}
True wind ('''V<sub>T</sub>''') [[Euclidean vector#Addition and subtraction|combines]] with the sailing craft's velocity ('''V<sub>B</sub>''') to be the ''apparent wind velocity'' ('''V<sub>A</sub>'''); the air velocity experienced by instrumentation or crew on a moving sailing craft. Apparent wind velocity provides the motive power for the sails on any given point of sail. The apparent wind is equal to the true wind velocity for a stopped craft; it may be faster than the true wind speed on some points of sail, or it may be slower e.g. when a sailing craft sails dead downwind.<ref name=Jobson2>{{cite book | last = Jobson | first = Gary | title = Championship Tactics: How Anyone Can Sail Faster, Smarter, and Win Races | publisher = St. Martin's Press | location = New York | year = 1990 | isbn = 0-312-04278-7 | pages = [https://archive.org/details/championshiptact00jobs/page/323 323] | url-access = registration | url = https://archive.org/details/championshiptact00jobs/page/323 }}</ref>
{{center|
;Effect of apparent wind on sailing craft at three points of sail
Sailing craft '''A''' is close-hauled. Sailing craft '''B''' is on a beam reach. Sailing craft '''C''' is on a broad reach.<br>Boat velocity (in black) generates an equal and opposite apparent wind component (not shown), which adds to the true wind to become apparent wind.
}}
<gallery mode="packed" heights="300px">
File:Forces on sails for three points of sail.jpg|'''Apparent wind and forces on a ''sailboat''.'''<br>As the boat sails further from the wind, the apparent wind becomes smaller and the lateral component becomes less; boat speed is highest on the beam reach.
File:Ice boat apparent wind on different points of sail.jpg|'''Apparent wind on an ''iceboat''.'''<br>As the iceboat sails further from the wind, the apparent wind increases slightly and the boat speed is highest on the broad reach. The sail is sheeted in for all three points of sail.<ref name = Kimball/>
</gallery>

The speed of sailboats through the water is limited by the resistance that results from hull drag in the water. Ice boats typically have the least resistance to forward motion of any sailing craft;<ref name = Kimball/> consequently, a sailboat experiences a wider range of apparent wind angles than does an ice boat, whose speed is typically great enough to have the apparent wind coming from a few degrees to one side of its course, necessitating sailing with the sail sheeted in for most points of sail. On conventional sail boats, the sails are set to create lift for those points of sail where it's possible to align the leading edge of the sail with the apparent wind.<ref name=Jobson/>

For a sailboat, point of sail significantly affects the lateral force to which the boat is subjected. The higher the boat points into the wind, the stronger the lateral force, which results in both increased leeway and heeling.  Leeway, the effect of the boat moving sideways through the water, can be counteracted by a keel or other underwater foils, including daggerboard, centerboard, skeg and rudder. Lateral force also induces heeling in a sailboat, which is resisted by the shape and configuration of the hull (or hulls, in the case of catamarans) and the weight of ballast, and can be further resisted by the weight of the crew. As the boat points off the wind, lateral force and the forces required to resist it become reduced.<ref name=Marchaj1>
{{Citation
 | last = Marchaj
 | first = C. A. 
 | title = Sail Performance: Techniques to Maximize Sail Power
 | publisher = International Marine/Ragged Mountain Press
 | year = 2002
 | edition = 2
 | pages = 416
 | isbn = 978-0071413107 }}</ref>
On [[ice boat]]s and [[sand yacht]]s, lateral forces are countered by the lateral resistance of the blades on ice or of the wheels on sand, and of their distance apart, which generally prevents heeling.<ref name=":0">
{{cite book
 |last = Bethwaite
 |first = Frank
 |title = High Performance Sailing
 |publisher = Adlard Coles Nautical
 |year = 2007
 |isbn = 978-0-7136-6704-2}}</ref>