I think they were all U boats. U followed by the number. I don't think they had names, not official ones like surface ships.
ADDED: They were just numbered, as you say. I believe the Federal German Navy still uses the same system ('U-boat' is only the Anglicised abbreviation for 'Untersee Boot', which means... 'undersea boat'). The Royal Navy names its submarines as it does for surface ships, but all RN vessels are also given fleet numbers.
German U-Boats are submarines. In World War 2, the Germans used these submarines to attack in groups of three or more. The Germans called these groups of submarines "wolfpacks". The Americans, British & Canadians also used the name "wolfpack" to refer to a group of German U-Boats.
the word in German is Unterseeboot -- literally, boat under the sea. The informal name for the vessels are U-Boat.
Submarines were sometimes referred to as submersibles.
the U boats..
Underseaboats.
In World WarII, the germans named it a uboat
A bad name for the Germans durring World War 2
The name U-boat was applied to German submarines.
'U-boats' was the name given to German submarines in both the first and second world war.
A German submarine used in WW I was called a U-boat.
The Bismarck .
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