Hi Willy,
Yes I should have more about this, but not as much as I would like to have. First of all however there was no U-boat S 35. All German U-boats were named U or UB or UC (however in reality there also existed for example UA or UE types,... but they were not officially named that way.
Also if we are talking about German U-boats operating against the US coast in WW I we are talking of the year 1918.
Of course there did exist earlier U-boat voyages to the US such as with the merchant U-boat Deutschland, but that is before war declaration of the US to Germany.
In fact it was June 1918 before the Americans were confronted in their homeland with the reality of U-boat war in the newspapers, some time after the first German U-boats had become active over there.
U151 was before the US coast from 15th May till 1 july, U156 from the 5th of July till the 1st of September, U140 from 14July till 1 September, U117 from left Germany early July, not known whenexactly arrived at US coast, but returned together with U140. U155 (the former Deutschland indeed) was in US waters from 7 September till 20 October, U152 from 29 September till 20 October. U139 ran out to the US in September but was recalled to Germany before it became active at the US coast.
I knew that subs went as far south as the North Carolina coast ( they didn't get any further to the south in fact) in the area of Cape Hatteras but it remains a question to me too which one it was.
For more details try posting at this forum which might give the answer :
http://uboat.net/forum/list.php?f=5
Best from Johan