▁is ▁ang led ▁in ▁a ▁slightly ▁more ▁forward ▁direction ▁than ▁the ▁sail ▁force . ▁In ▁this ▁aspect , ▁the ▁boat ▁will ▁move ▁forward ▁because ▁the ▁ke el ▁( center line ), ▁of ▁the ▁boat ▁acts ▁to ▁the ▁water ▁as ▁the ▁sail ▁acts ▁to ▁the ▁wind . ▁The ▁force ▁of ▁the ▁sail ▁is ▁bal anced ▁by ▁the ▁force ▁of ▁the ▁ke el . ▁This ▁keeps ▁the ▁boat ▁from ▁moving ▁in ▁the ▁direction ▁of ▁the ▁sail ▁force . ▁Although ▁total ▁sail ▁force ▁is ▁to ▁the ▁side ▁when ▁sail ing ▁into ▁the ▁wind , ▁a ▁proper ▁angle ▁of ▁attack ▁moves ▁the ▁boat ▁forward . ▁ ▁Another ▁way ▁of ▁stating ▁this ▁is ▁as ▁follows : ▁ ▁In ▁practice , ▁optimal ▁sail ing ▁in ▁the ▁direction ▁from ▁which ▁the ▁wind ▁is ▁coming ▁will ▁usually ▁be ▁at ▁a ▁course ▁of ▁around ▁forty ▁five ▁degree ▁angles ▁to ▁the ▁on coming ▁wind . ▁To ▁reach ▁a ▁particular ▁point , ▁altern ating ▁the ▁direction ▁of ▁the ▁wind ▁between ▁the ▁port ▁and ▁star board ▁side ▁is ▁usually ▁necessary . ▁This ▁is ▁called ▁" t ack ing ." ▁ ▁Disc uss ion ▁ ▁The ▁points ▁of ▁sail ▁clarify ▁the ▁real ities ▁of ▁sail ing ▁into ▁the ▁wind . ▁One ▁of ▁the ▁points ▁of ▁sail ▁is ▁" Head ▁to ▁Wind ." ▁A ▁boat ▁turns ▁through ▁this ▁point ▁on ▁each ▁tack . ▁It ▁is ▁the ▁point ▁at ▁which ▁the ▁boat ▁is ▁neither ▁on ▁port ▁tack ▁or ▁star board ▁tack ▁and ▁is ▁head ed ▁directly ▁into ▁the ▁wind . ▁However , ▁a ▁boat ▁cannot ▁sail ▁directly ▁into