The shipbuilding industry in the seventeenth century. witnessed far-reaching changes that mainly resulted from imitating European techniques. The Indian sea-going ships, until the first half of the seventeenth century, were called 'junks' by the Europeans. These were very large and supported immense main sails. In some ways, the imitations even improved upon the originals. The Indian method of riveting planks one to the other gave much greater strength than simple caulking used by European ship-builders. A lime compound dabbed on planks of Indian ships provided an extraordinarily firm protection against sea-weeds. However, it was the instruments used on ship where India lagged much behind Europe. Indians failed to fashion modem navigation instruments. The main instrument used on Indian ships still remained the astrolabe. Later, in the seventeenth century, European captains and navigators were employed on Indian ships, and they naturally used telescopes, quadrants, and other instruments that were imported from Europe.
One important device that had a great potential in the manufacture of precision instruments and machinery was the metal screw. It came into use in Europe from the middle of the fifteenth century for holding metal pieces together. Its use was of great importance in mechanical clocks. The screw began to be used in India by the second half of the seventeenth century and even then it was a less efficient version of the European screw. The grooves were not cut, but wires were soldered around the nail to create the semblance of grooves. This had to be done owing to the absence of lathes which were used in Europe for cutting grooves. Dueto this limitation, the Indian screw did not fit properly.