How did the series of navigation acts affect the colonies?

The Navigation Acts were primarily targeted at trade with the Spanish and the Dutch. Under the acts, American colonists had to use British ships to sell to them. Later acts would require that the colonists only sell in British markets. Many colonists complained as they could get better prices for their goods in other markets. Several colonists thought nothing of trading in Dutch and Spanish ports, even in times of war. The colonists rebelled by not buying British goods and selling in other markets anyway.
Before the French and Indian War, Parliament did not enforce the laws very closely, through a system of salutary neglect. After the French and Indian War, when British officials got a close look at colonial tax dodging and lawbreaking, Parliament decided to enforce the Navigation Acts and try its offenders in admiralty courts. The Navigation Acts were but one part of Parliament's role in driving the colonists to revolution.