I noticed in "Today's Date" listings that U-359 had been sunk south of Santa Domingo in late July, 1943. That seemed late to me; I looked up data on Typ XIV supply boats and found that May - early August was a terrible time for the supply boats. In mid-May, 1943, Donitz had 8 Typ XIV boats: in just over two months, he had only 2 left. Of those, U-460 was out of service (returning from patrol or in port) for Jun-August, 1943 and was sunk in early October, 1943 on her next patrol.

(May - August Typ XIV Sinkings)
463 16 May, 1943
487 July 13, 1943
459 July 24, 43
461 July 30, 1943
462 July 30, 1943
489 August 4, 1943

That left only U-488, which only completed 3 patrols before being sunk on April 26, 1944. (Since U-490 was sunk before it had ever supplied any other U-boat, we can disregard it for operational purposes.)

The Typ X "minelayers" were used to some extent for supply of other front boats and there was some "juggling" -- boats that had to abort patrols would meet other boats to transfer fuel before returning to port -- but it appears that any real capability to supply Typ VII boats in the Caribbean ended about the end of July, 1943.

It is an accepted principle that the War changed for U-boats in the summer of 1943 (better Allied tactics, more Allied vessels, better radar and sonar/Asdic, better new weapons, closing of the "air gap", escort carriers, better air bases in the southern US, Bermuda, the Caribbean, and South America, etc.) Was the U-boat service able to operate Typ VII boats in the Caribbean or South Atlantic to any degree of operational success after July 1943? (Of course, Typ IX boats were a threat until the end of the War -- and U-195 was sunk near U-359 within a few hours -- but it appears that the ability of Typ VII boats to operate in the Western Atlantic and Caribbean waters was limited from this time onwards.)

Discussions?