It is considered a good example of early modern, functional design.
Equipment changes added 5 tons to the earlier 100-ton design.
The earliest design is of 1608; construction took from 1621 to 1625.
This was less susceptible to damage than the earlier design.
The earliest designs were thought to be more than 3000 years old.
Introduced in that same year, it replaced an earlier design which had been used since 1946.
The invention was made around 1786, although some say he only improved on an earlier design.
This fish shape was from a typical early Chinese design.
The earlier design was never built and the current plan replaced it sometime around 2003.
However, his earlier designs were not well received by combat troops.