The decline of naval and trading superiority experienced by the Dutch began because of the lack of strong leadership after William III died and because there wasn't another strong stadholder, the wars with France and England, the lost of technological advances once the British caught up, the domestic industries losing in the competition with British merchants, and the reality that the Dutch couldn't compete in overseas markets with larger powers such as France and Britain all lead to the economic decline of the Republic.
Prior to 1650 the Dutch Republic was dominated financially, politically and economically by Amsterdam, the leading banking city in Europe. The Dutch prospered from the Domestic industries of fishing, boat building, textiles and banking. The Dutch were also the most technologically advanced sailors in Europe.
The British and French demonstrate that a strong central power is necessary to maintain power on a world scale. The Republic doesn't have this unity after William III dies, "the government of the Dutch Republic is shattered and divided," as stated in document 4. Holland is also the only wealthy province, due to the banking industry of Amsterdam and therefore has to have the burden of financing all wars for the Dutch.
The wars with France to the South and England to the West surround the Dutch. Document 6 shows the determination on the part of the British and French to dominate the Dutch, "the king of France will defray all expenses of the campaign by land," and the "for the war at sea the king of England will arm at least 70 warships." The Dutch Provinces" size and location made it vulnerable to attack and economic challenges. Document 3 shows the losses suffered by the Dutch as compared to the British due mostly to the size of the Navy and the strategic location of England. In 1650 their economic power was extremely great compared to the Republic's size and population.