Career
In 1525 Koel was commander of one of four ships of the fleet of Admiral Simon Parseval. 7 October he came into sea battle with the fleet of the pirate Claus Kniphoff. After 8 hours he managed to take the ship Gallion.
He brought the pirates and the loot to Hamburg, and was 1527 elected to Ratsherr (councilman).
Koel promoted the Reformation and initiated the reformation of the Hansatown. In 1536, as Admiral for a defence fleet, he stopped a raid from palatinate count Friedrich von Hadeln.
From 1542 until 1548 Koel was Amtmann of Bergedorf., wo er die Abfassung einer neuen Kirchenordnung veranlasste. In 1548 Koel was elected mayor of Hamburg.
In 1559 he was in command of the defence of Hamburg-Moorburg against an attack from duke Otto I, Duke of Brunswick-Harburg.
In 1562 he traveled with two colleagues in a diplomatic journey to Copenhagen, in order to settle a conflict with the Danish king. Successfully, he returned to Hamburg, where he died on 22 September 1563. Streets Ditmar-Koel-Straße in Portugiesenviertel in southern Neustadt is named after him, as well as another Ditmar-Koel-Straße in Cuxhaven.
Ships 1935 a pilot boat was named Ditmar Koel.
1955 a steamboat owned by the Emil Offen & Company had his name. 1958 a pilot boat made by Meyer-Werft in Papenburg was named after Koel.