There were several types of U-Boats and they were different sizes.
Type VII was a common type. It's overall length and width were 120 feet x 20 feet. The inner pressurized hull (livable area) was about 2/3 of these diminsions.
The Allies sunk German Uboats. Uboat, not you-boat. Uboats stand for Unterseeboot - undersea boat.
a group of German uboats that hunted Allied and US ships
The invention of radar helped the Allies to locate and sink the German U Boats.
Yes the Germans created uboats, they have had them since the dawn of time, litterally
The Germans then threatened to use only Uboats for war and blew up a few ships.
because of the alliances the US had made previous to the start of the war along with the threat of the German Uboats attacking US civilians and property.
items were in short supply for Britain because all their cargo ships bringing food and other things in from the US were torpeoded and sunk by the German UBoats
big is groß in German.
The submarines attacked Pearl Harbor
big - groß
No. It is an urban legend. They were seen by a shipyard worker but they never fired. It is understood the UBoats were doing reconnisance duties of the Eastern Coast of the USA. There have been accounts of people in Boston seeing them too.
this answer is not quantifiable