[Kapitän]

Originally Posted by Kapitän

Started new career in August 2019 to commemorate the beginning of WWII, 80 years before ...

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U 115
- KTB -
First War Patrol
(17th war patrol overall)

Saturday, 6 March 1943 - Kiel Kriegsmarinewerft

Final Adjustments and Pre-War Patrol Preparation:

- Loading of Fuel: 441t => 510cbm (at 865kg/m³) - 95 on gauge => 100%.

- Trimming trials in Kiel harbor.

Daily Op.-Briefing:

A) 1) The systematic evaluation of the English U-boat situation for the month of January and the beginning of February is reassuring, in view of the strong suspicion that the enemy had broken down our codes or otherwise obtained exceptional knowledge of our operations. (compare the English estimates of U-boat positions, confirmation of the facts accessible to the English, wireless bearings, sightings, U -boat attacks, a/s radar, also information obtained after the return of a number of U-boats.)
Except in the case of 2 - 3 unexplained incidents, English information from the facts accessible to him of U-boat positions, and plots of the boats, can throughout be traced to an explainable combination of facts. The most important revelation - confirmed almost without a doubt - was, that the enemy was able, with the help of a/c radar, to intercept U-boat dispositions with great accuracy - adequate for the successful evasive action of his convoys. As always, our countermeasures limp several weeks behind this kind of new enemy practice because:

a) His evasive measures are obvious, only after constant use, partly after receipt of English wireless messages (Special Radio Intelligence messages) not solved for weeks afterwards.
b) Reports of confirmed wireless location of U-boat dispositions, are rarely received by W/T, their use is not apparent until the operational survey and Commander's oral report.
c) The technical possibilities of "ASV" location (simultaneous confirmation of several targets at long range and thereby the simultaneous interception of several boats in one disposition) was still unknown.

A) 2) The fact perfectly corroborated by the increasing appearance of the additional word "radio located" in English U-boat situation (reports) of confirmation of U-boat dispositions by a/c radio location, meant an uncomfortable complication of the method used up to now, of intercepting convoys by patrol lines. As, in many cases, the inadequate number of U-boats in the patrol channels cannot be dispensed with.

a) The boats are ordered to submerge for about 30 minutes on confirmation of a/c radar. (Stipulation for the effective execution of this measure is the presence of a constantly used Fu.M.B. in good working order. The Fu.M.B. aerials at present in use in the ops. areas are however not practicable in all weather conditions. An alteration will not be made until the beginning of March, the time of the equipping of boats with fixed Fu.M.B. cable and round dipole.)
b) Avoid all unnecessary waiting in patrol lines before the presumed convoy passage time. (Disposition of the groups: "Neptun", "Ritter", "Burggraf", "Neuland"). These groups were to proceed on a westerly to southwesterly course on the convoy routes as far as the area of Newfoundland Bank "Harken". The passage speed was for the most part very small in the bad weather conditions generally prevailing; the disposition could almost be considered stationary in view of the long range of the "ASV" apparatus and the high speed and radius of action of English a/c. Up to now no better method has been tried. All other dispositions, i.e. the indiscriminate, unsystematic spreading out of boats in a certain area, ("castor sugar") have the disadvantage of too large spaces between the individual boats. After the non-interception of a convoy by such a disposition there is always the riddle what's to be done. The required certainty is lacking in a clear lineal disposition in any case up to a certain point (adverse weather conditions, periods of fog excepted), that the convoy has not sailed through the disposition area, that then, an alteration of the area and method is necessary.

U 648 (Ltnt.z.S.d.R. Peter-Arthur Stahl) undergoes Final Repairs at Blohm & Voss shipyard Hamburg.

RST
KorvKpt.& Cmdr. U 115

Started new career in August 2019 to commemorate the beginning of WWII, 80 years before ...

+++++++

U 115
- KTB -
First War Patrol
(17th war patrol overall)

Sunday, 7 March 1943 - Kiel Kriegsmarinewerft

Final Adjustments and Pre-War Patrol Preparation:

- Testing of Navigational and Radio Equipment.

- Loading of Provisions, Ammunitions and Torpedoes:

Ari and A/A ammunition:
- 10,5cm-SK-C/32: 150 x SpG; 80 x PbG; 20 x LkG
- 3.7cm-SK-C/30: 2550 x PbG
- Twin-M.G.-2cm-C/30: 5280 x SpG (2 x 2640); 2720 x PbG (2 x 1360)

Torpedoes:
- Tubes I-IV & VI: T-3 (G7e), Pi-2/Pi39H (MZ/AZ)
- Tube V: T-4 "Falke" Pi-2/Pi39H (MZ/AZ)
- Bow above floor plates: 2 x T-3 (G7e), Pi-2/Pi39H (MZ/AZ)
- Bow under floor plates: 4 x T-1/G7a FAT (AtoFat), Pi-1/G7H/K-a (AZ only)
- Aft under floor plate: 3 x T-1/G7a FAT (AtoFat), Pi-1/G7H/K-a (AZ only)
- Upper deck containers: 10 (8 fwd, 2 aft) x T-1/G7a (Ato), Pi-1/G7H/K-a (AZ only)

Daily Op.-Briefing:

B) 1) Warfare against the African supplies from North America in the area north and south of the Azores has led to failure. Neither a U.G.S. or G.U.S. convoy has been intercepted by means of a patrol or reconnaissance channels ("Rochen, Robbe"). The enemy's possibility of taking evasive action north or south of the Great Circle are very great - owing to the great length of the entire route without any significant extension of the convoy route.
B) 2) The tricky situation of the forces defending the bridgehead Tunis, forces action against African supply lines. As, for one thing, the attacking of the convoys in the area of the Gibraltar lines is unpropitious owing to strong defence, for another, as described in 1), the interception of convoys halfway is pointless in view of the size of the area, the following is the remaining possibility:
Deployment of U-boats off the North American departure ports. Interception here and pursuit to open sea.
It must be ascertained in this connection:
a) The aerial defences off the coast is apparently very strong, disposition must therefore be stationary.
b) Facts of ports of departure and times of leaving are unpredictable therefore a certain number of boats are necessary
c) Defences, taken as a whole, mean a withdrawal to outside the coastal area during the full moon period. Consideration of these facts leads to the demand for an adequate number of boats, some of which would act as reconnaissance units stationed directly in front of the harbor, the others further out to act as "pick-up" groups able to operate on the reconnaissance groups reports. Owing to the length of the approach route, only a small percentage of U-boats (at the moment type IXc) come into the question. The following boats originally intended for deployment in the Cape Town area were distributed for this: U 172, U 515, U 513, also U 167, U 130, U 106, U 159.

U 648 (Ltnt.z.S.d.R. Peter-Arthur Stahl) undergoes Final Repairs at Blohm & Voss shipyard Hamburg.

RST
KorvKpt.& Cmdr. U 115