Yong-le: Year 2, Month 1, Day 19
29 Feb 1404
The people were prohibited from going to sea. At this time, the coastal residents of Fu-jian were privately loading up ocean-going ships and communicating with foreign countries. Thereby piratical attacks had ensued and the prefectures and counties advised. Subsequently, an order was issued prohibiting private ocean-going ships, requiring that the existing ocean-going ships be all turned into "flat-topped" ships (平頭船) and that the local officials prevent people from coming and going by ship.
Zhong-yang Yan-jiu yuan Ming Shi-lu, volume 10, page 498