From some googling it seems like the british and americans named their u-boats not after people, but at least with names that stuck out ("USS Tang" and "HMS Thule") while the germans used U+a number from 1 up to a 1000. I always imagined that naming a boat would give the crew and civilian fondness for it, and it seems strange that the german command who appear propaganda savy, would forfeit the opportunity to do this. "U-120 sunk a british battleship!" doesn't sound as striking as "German battleship sunk by the HMS Fortitude!" when it comes to newspaper headlines.
Is there a known reason for the naming convention of the german u-boats? And did this reflect an attitude in the kriegsmarine that submarines were below in rank or prestige, to the typical surface ships of the german navy?
PS. Searching through Askhistorians I found this answer which seems to indicate that submariners had a good status in the german navy.
You are correct in thinking that issues of status were involved. Submarines and torpedo boats were boats, not ships, and thus were accorded lesser importance in the naval hierarchies of the time. The Royal Navy, for example, called named its torpedo boats by number, but its torpedo boat destroyers (later simply "destroyers") got names – they were ships.
Although, technically, submarines are still "boats" and not "ships" today, the RN began giving its submarines names rather than numbers after the First World War, by which time they were clearly established as a significant weapon of war. Prior to 1918, however, they were numbered in the same way as U-boats were. The first five British submarines were built to plans supplied by the US Holland company, and were named Holland I to Holland V. Thereafter the British produced successive classes of submarines that were known by their class initial and a number (thus, A7, E11).
A general tendency to give unglamorous number-based names to grimly functional vessels can be perceived in most navies at least as late as World War II – thus the US Crane Ship No.1. It's therefore interesting to note that the French, who took submarines far more seriously at a far earlier date than did the British or the Germans, and worked them into their Jeune Ecole theorising, seeing them as weapons that would allow the French navy to gain parity or superiority over the battleship-based British fleets, gave their submarines names from as early as the 1860s.