Maciek,

U 596 was directed to get a schnorkel installation on 23 May 1944 - it was fitted at Pola Werft (Croatia) between 23 May and 28 June 1944. Schnorkel training for this boat took place between 6-8 July 1944. First operational use of the schnorkel was on 30 July 1944.

U 264 - Schnorkel testing between 16-28 January 1944 - initial test was cancelled due to faulty supply air valve head on 16 January 1944 and returned to St. Nazaire for repair. Eventually sailed on patrol 5 February 1944 and the boat was lost on 19 February 1944.

-- Regards,
Ken Deshaies
Newton, New Hampshire