What were the Navigation Acts?

"The measures, originally framed to encourage the development of English shipping so that adequate auxiliary vessels would be available in wartime, became a form of trade protectionism during an era of mercantilism.

The first navigation act, passed in 1381, remained virtually a dead letter because of a shortage of ships. In the 16th century various Tudor measures had to be repealed because they provoked retaliation from other countries. The system came into its own at the beginning of the colonial era, in the 17th century.

The great Navigation Act passed by the Commonwealth government in 1651 was aimed at the Dutch, then England’s greatest commercial rivals. It distinguished between goods imported from European countries, which could be brought in either English ships or ships of the country of origin, and goods brought from Asia, Africa, or America, which could travel to England, Ireland, or any English colony only in ships from England or the particular colony.

Various fish imports and exports were entirely reserved to English shipping, as was the English coastal trade. The law was reenacted in 1660, and the practice was introduced of “enumerating” certain colonial products, which could be shipped directly only to England, Ireland, or another English colony. These included sugar (until 1739), indigo, and tobacco; rice and molasses were added during the 18th century.

Nonenumerated goods could go in English ships from English colonies directly to foreign ports. From 1664 English colonies could receive European goods only via England. Scotland was treated as a foreign country until the Act of Union (1707) gave it equal privileges with England; Ireland was excluded from the benefits of the laws between 1670 and 1779."

Source and more details:https://www.britannica.com/event/Navigation-Acts