Spähkreuzer was a large destroyer (or reconnaissance cruiser) of the German Kriegsmarine. 
Kreigsmarine Destroyers - Spähkreuzer Class (D-38) ==========================================================================
Although called Spähkreuzer (Reconnaissance Cruiser) these ships were basically large destroyers capable of operations in the North Atlantic. Based on traditional destroyer design, several project studies started in 1938 to develop a large destroyer of the size of a light cruiser. Like most German cruisers, these ships were planned with a mixed propulsion system, steam turbines for high speed and diesel engines for long cruises. It was planned to use these ships in combination with the new battleships of the Plan Z in the North Atlantic where the Spähkreuzer should be the eyes of a larger battle fleet.
In terms of armament they were closer to light cruisers than the typical destroyer. The use of 5.9 inch (150 mm) guns was atypical of destroyers which tended to have guns around 4.7 to 5 inch (120 - 127 mm) in calibre. They were intended to carry their forward guns in a twin turret, but as the twin turrets were not ready in time they initially carried single mounted guns.
Despite being powerful the ships were not without their flaws. There were problems with the reliability of the high pressure steam engines and seakeeping in rough seas due to the newly designed bow and heavy forward artillery.
With the lessons learned by the first naval actions in World War II, the plans for the Spähkreuzer were modified several times, after the "Spähkreuzer 38" later designs were called "Spähkreuzer 39" and "Spähkreuzer 40" which had improved range, armor protection and a float plane on board.
The first three ships (SP1, SP2, and SP3, formerly named Z40, Z41, Z42) were ordered in February 1941 at the Germania Shipyard in Kiel. In December of 1941, the engines for the next three ships (SP4, SP5, SP6) were ordered too, but not the ships themselves.
Only SP1 was laid down, but its construction plans were destroyed during a air raid. In April 1942, construction of all Spähkreuzer was stopped and the focus switched to the construction of normal destroyers.
=================================================================================
NB: The above text has been collected / excerpted / edited / mangled / tangled / re-compiled / etc ... from the following online sources :
KM - Destroyer Spähkreuzer - wikipedia
KM - Destroyer Spähkreuzer - www.german-navy.de
