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.