Found a reference that gives a more detailed acounting of the U boats as of Sept and Oct 1940:
http://forum.axishistory.com/viewtopic. ... &start=135
Planned U-Boot deployment for SEELÖWE:
(7 Type IX in the western entrances to the Channel, off the Cornish Coast, withdrawn from the plan by Group West, possibly for weather reconnaissance duties)
10 Type VII in the western channel south of Start Point
9 Type II off the western minefields, between the Isle of Wight and Beachy Head
6 Type II in the southern North Sea between East Anglia and Holland
2 Type II off the Northumbrian Coast
3 Type II and 2 Type VII off the entrances to Scapa Flow
Total required: 39 U-Boats (20 Type II, 12 Type VII, 7 Type IX). In all respects this was weaker than the force generated for Weserübung that had such disasterous results in April.
Actually operational as of 1 October:
Type IX - 7, plus two working up (one just commissioned 10 Sep and the other made its first patrol on 10 Nov). But of those available, 5 were actually already on patrol, sailing 15, 21, 21, 24, and 25 Sep, while the other 2 had just returned from patrol on 16 and 25 Sep.
Type VII - 13, plus 4 working up (one just commissioned 14 Sep and the others all made their first patrols in Nov). Of those available, 2 were no longer considered fit for operations and were withdrawn to the training command, 3 were actually already on patrol, sailing 16, 17, and 23 Sep, 7 returned from patrol on 16, 17, 25, 25, 25, 25 Sep, and 1 Oct, and 1 was refitting sailing on 7 Nov.
UA - was refitting.
Type II - 19 were in the training flotillas, of which 8 were no longer rated capable of frontline duties. Of the 13 in the operational flotilla, 5 were being transferred to the schools, of which 1 was no longer rated capable of frontline duties. Of the remaining 8, two sailed on patrol 16 and 17 Sep, 4 had returned from patrol 15, 20, 21, and 26 Sep, and the last two were working up with 1 commissioned on 4 Sep and the other making its first war patrol on 20 Nov).
Note that the typical turnaround time after returning from a war patrol was five to seven weeks depending on the amount of refitting and repairing that was required. So overall it appears that those probably available for commitment were:
Type IX - the 5 actually already on patrol....shortfall to plan was 2.
Type VII - the 10 actually already on patrol, of which 7 were nearly at the end of their patrol....shortfall to plan was 2 and by 1 October it would be by 9.
Typ II - 23 were still considered fit for frontline service...if the schools were stripped of all available boats, most of which would then sail with partly trained crews - at best. Practically there were at most 10 available, including 2 on patrol and 4 about to return from patrol...shortfall to plan was 10.
Total at the time
Type IX - 7 + 2 working up
Type VII - 13 + 4 working up
Type II - 32, 19 assigned to schools 8 of which were rated not fit for front line service and 13 in operational squadrons with 5 being transfered to the schools of which 1 was rated not fit for front line service, of the remainder 2 were working up. So if they raided the schools they end up with 25 uboats with well trained crews, 8 in the process of working up, and 15 school boats probably roughly equivalant to the 8 working up. But to get that many they have to have started cancelling patrols no later than the beginning of August and by early September none will be operational in the Atlantic. That's also rather optimistic for turn around times for some returning from patrols as well.