Rob,


To combine reponses to posts, yes, you really pretty much do need a wreck. Also remember that mines were the single greatest cause of U-boat losses in WWI and the missing submarines operating in this area had to cross significant mine barriers to get back home. Operational loss is always a possibility as well.

Sinking claims without plausible victims don't amount to much. Also, oil and air by themselves don't mean much as both can come to the surface from relatively minor damage that is external to teh pressure hull.

The Oct. 4, 1917 claim is problematic for a number of reasons. No ship was torpedoed on that date in that area, which makes me wonder if the date is correct. Assuming it is, there isn't really a plausible victim. The closest would be UC 21, which sailed on Sept. 13 but the record patrol length for a Flanders-based UCII operating through Dover is only 20 days. 21 days plus another two to home is extremely questionable.

It's hard to do something with "sometime in December 1917." The only vague possibility would be UB 18, which is commonly listed as being rammed by a navy trawler on December 9, 1917. If that wasn't the case, then maybe.

Best wishes,
Michael