Wind-Ships movement

According to history,man's domination over
seas has proceeded on a long path,the
beginning of which is not yet known well.On
the basis of the existing evidences,the first
boats were probably built in very ancient
times, that is during the Neolithic age,by
the people living near seas and lakes.These
boats were in fact only trees or lumbers
which helped men who werenot much of
a swimmer.

What is for sure is that ship building and
using water transportation vessels like
what is now a days called as ship,has been
prevalent since centuries and even thousands
of years ago. The story of Noah ship P.B.U.H
in the Holly Quran is an evidence to support
this argument. Also Yaqubi , in his history,
states that,imitating Noah,the first Chineese
king named Saayn,build a ship and boarded it
with a number of his children and sailed seas
until he reached a territory which he liked
and chose to dwell. The land was named after
him " Seen ". In this regard,Iranians played
a significant role in the development of ship
industry and also using ships.It is said that
among Iranians the first person who attempted
to build ships was mythical Jamshid , from
Pishdadian lineage ) family ( . Evidences
indicate that during the Achaemenian dynasty,
Iranians were the absolute rulers of the
Mediterranean sea for a short period from
525 to 480 BC . Also the Sassanides'
(another Iranian dynasty( navigation extended
up to Chineese ports . It can definitely be
said that Iranian were the only sailors
taking voyages to China prior to the nineth
century AD.They carried out trade with Far
East before Arabs . Prior to Islam , Arabs
probably did not enjoy much ship building
and naval skills.The fact which has caused
Moslems to be sufferring from this weak point
from the very beginning . Martin Hatman
believes that Islam ) or it is better to say
Moslems ( scared seas . Moyer ) Caliphate,
Grandeur,Decline and its fall;pp 2981 , 212 )
too has stated the same idea by mentioning
the Ommaid caliph's attack of Syrian seashore
and Amr-o-Aas' sletter to him.Yaqubian
history also indicates that following the sea
defeat sustained in the war with Romans,Omar
( the second Moslem caliph ( swore he would
no more send anyone on a ship.Arabs living on
seashores,on the other hand,were generally
peace-loving traders,and did not intend to
get prepared for entering naval arenas.
This fact was quite conspicious during the
Sassanides dynasty;for,in spite of the fact
that after the fall of Yazdqerd during the
caliphate of Osman )the third Moslem caliph)
Iranian emperorship ended,Iran's sea trade in
Far East was still carrying out during the
caliphate of Motevakel ) 847 - 861 AD ).

But in the light of the teachings of Islam,
Moslems become acquinted with naval
techniques and used the related instruments
very soon.Up to the caliphate of Motevakel,
Moslems almost decreased the inequality which
existed between them and other sailors
especially Iranians so much that during
the rule of the Abbassides important Arab
caravans of ships went to China,and their
trade representatives wereactive on the
seashores of China,India and East Africa.
Anyhow,this industry,as one of the important
industries in the fields of trade,military
and tourism is now of interest to many
countries and it is as a result of such an
interest that nowadays hundreds of kinds of
ships are floating and in constant traffic
on ocians.

Thereason for the floating of ships is
generally related to Archimedes's law
( 287 to 212 BC (. According to this law
when an object is submerged into a liquid,
it gets lighter as much as the weight of
the liquid equal to its volume.This law is
in fact derived from the use of Newton's
laws and taking into account fluids
properties.In a simple statement,it can be
said that since the volume of the air in
a ship is much more than the volume of the
steel used in its construction,therefore,
the mean density of the ship is less than
the density of water,and hence,the ship
floats on water.

It worths saying that in the beginning almost
all primitive ships were made of materials
which had lower density than water,so that
they wouldn't sink. From 1800 onward ,when
iron production increased,for the first time
engineers thought of building ships from
iron.This thought was first mocked by people.
Of course they didn't know that if they
scrape off a piece of iron bar and make its
walls so thin that its mean density becomes
less than the density of water,it will float.