By the Second Anglo-Dutch War, you started to see Dutch admirals have flag captains, rather than commanding their own ship

At the start of the First Anglo-Dutch War, you seem to have Dutch flag officers commanding their own ships. Before long, that changed. It may well be that Lt-Admiral Tromp always had a flag captain, but he certainly had one by later in 1652. By the time of the Four Days Battle, you saw men like Schout-bij-Nacht Jan Janszoon van Nes with a flag captain for his ship, the Delft (62 guns). His flag captain was Laurens Kerseboom. The Delft was a brand new ship built by Rotterdam, completed in 1666. Her dimensions were 146ft x 38ft x 15ft. Her armament at the Four Days Battle was: 8-brass 24pdr, 3-brass 18pdr, 13-iron 18pdr, 5-brass 12pdr, 17-iron 12pdr, 10-brass 6pdr, and 6-iron 4pdr. Her crew consisted of 217 sailors and 62 soldiers. Her intended crew was 260 sailors and 4 soldiers.