Question: Grand Admiral a naval rank in one of the highest in the several European navies that use this system, what system are they using? 

Related documents: [0]  [DOC] Grand admiral is a historic naval rank, the highest rank in the several European navies that used it. It is best known for its use in Germany as "Großadmiral". A comparable rank in other navies is that of fleet admiral. [END] 
[1]  [DOC] Military ranks are a system of hierarchical relationships in armed forces, police, intelligence agencies or other institutions organized along military lines. Usually, uniforms denote the bearer's rank by particular insignia affixed to the uniforms. Ranking systems have been known for most of military history to be advantageous for military operations, in particular with regards to logistics, command, and coordination; as time went on and military operations became larger and more complex, military ranks increased and ranking systems themselves became more complex. [END]  
Answer: Military ranks
Military ranks