Considerably longer than that. Read Roger Moorhouse’s latest work (Wolfpack: Inside Hitler’s U-Boat War): the sailors in WW2 uboats were routinely taking 6 week tours by mid-war, and type IXD2s eventually took that up to 200 days.
U-196 made a 225-day journey, and her crew had to hot bunk. That’s like putting 48 men into a slightly smaller volume than a type-S scout and sending them out for a 25-jump journey with only wilderness refuelling.
