Questions on U Boats 1942-1943

[Bubblehead1980]

Originally Posted by blackswan40

Hi Bubblehead ive done some diging on the internet and found this hope it helps some


https://www.history.navy.mil/researc...elligence.html


when i play the GWX Steel Sharks Campaign than run the gauntlet running on the surface in the bay of biscay i would dive to periscope depth as soon as i had enough depth under my keel.


U flak info below

https://uboat.net/types/u-flak.htm

normal crusing speed of a type VIIB,C-IXB,C would be 7knots that was deemed the most economical for fuel consumption and distance traveled

Thanks

[Bilge_Rat]

Hi, rechecked my copy of Blair's "Hitler's U-Boat war".

1. seems to have depended on the Skipper. By this time, the bay of Biscay was a very dangerous place with high Allied air coverage. Since Coastal Command ACs were equipped with radar and Leigh lights, surfaced U-Boats were never safe. At night, the sound of ACs was drowned out by the U-Boast diesel. U-Boats preferred travelling on the surface during the day because it was easier to spot ACs from a longer range. Seems that they would have generally traveled on the surface at higher speeds to get through the Bay faster;

2. U-Flak, it was from about june to october 43. The U-Flak escort concept was given up quickly because it just lead to increased U-Boat losses;

3. normal speed. Again depends, best fuel economy speed was using one engine only, 6-7 knots, but that was generally only used when they wanted to stretch range to the limit, for example patrols by VIIs to the U.S. East Coast when they did not have access to U-Tankers. Normally for mid-Atlantic patrols, they would follow orders from U-Boat Control which would often switch them to new patrol zones. Normal cruising speed in the mid-Atlantic was probably more in the 10-12 knots range.

[Bubblehead1980]

Originally Posted by Bilge_Rat

Hi, rechecked my copy of Blair's "Hitler's U-Boat war".

1. seems to have depended on the Skipper. By this time, the bay of Biscay was a very dangerous place with high Allied air coverage. Since Coastal Command ACs were equipped with radar and Leigh lights, surfaced U-Boats were never safe. At night, the sound of ACs was drowned out by the U-Boast diesel. U-Boats preferred travelling on the surface during the day because it was easier to spot ACs from a longer range. Seems that they would have generally traveled on the surface at higher speeds to get through the Bay faster;

2. U-Flak, it was from about june to october 43. The U-Flak escort concept was given up quickly because it just lead to increased U-Boat losses;

3. normal speed. Again depends, best fuel economy speed was using one engine only, 6-7 knots, but that was generally only used when they wanted to stretch range to the limit, for example patrols by VIIs to the U.S. East Coast when they did not have access to U-Tankers. Normally for mid-Atlantic patrols, they would follow orders from U-Boat Control which would often switch them to new patrol zones. Normal cruising speed in the mid-Atlantic was probably more in the 10-12 knots range.

Thanks Bilgerat, big help. Guess U flak will make limited appearances as SubRon 50 boats transferred to PTO in July 1943.

Many, 6-7 knots lol, slow going.

[Aktungbby]

Blackswan'40s extremely detailed site on what is the "wizard war" a radar/counterradar stuggle where German Uboats were preoccupied with their radar detection devices: metox etc. actually giving away the uboats' position; caused Uboats to remain submerged at night transiting Biscay and surface in daylight to charge batteries and chance being able to visually spot the inbound radar aircraft. The advent of the schnorkel, while not entirely proof against airborne radar with an extended schnorkel, was the best defense overall. Ultimately, by 1944 and during the invasion, only Uboats so equipped were sent out from the French ports.

Originally Posted by Bubblehead1980

Did they depart/arrive on surface at night only by this point? OR given radar, leigh light, etc were they safer on surface in day time or submerged in the bay?

The Germans take stock
After several months of failure by the Germans to find the cause of their misfortunes, it was apparent that the U-boat Command and its commanders had lost faith in their search receiver. In the Bay of Biscay U-boats began to spend the nights underwater. Preferring to take a chance on visual sighting of an enemy during daylight for the period of time necessary for ventilating and charging the batteries. In July 1943 the Director of the Naval Communications Division, German Naval War Staff, admitted in long communication concerning the search receiver service that the "invisibility" of the U-boat was gone, that the element of surprise in U-boat attacks had been eliminate by new Allied location methods which had so far proved inaccessible to interception. The Director outlined plans for overcoming the German deficiency, including increased use of radar itself by naval and coastal defense forces. Taking note of many serious mistakes made in the past, he announced extensive changes in organization and procedure aimed at strengthening radar and radar interception research and practices, and stated that the Commander in Chief of the navy had promised his special support toward attaining that end, as indeed Admiral Dönitz had promised U-boats in May..... During the invasion, Schnorchel was used to the limit of its capacity and allowed operation by U-boats against invasion traffic at a time when air coverage was as effective as to necessitate the recall to port of all U-boat's not equipped with Schnorchel. The device was considered of such importance that its installation was designated the chief task of U-boats in port in August 1944. Although Schnorchel was not immune to detection by radar, it was much less susceptible than a surfaced U-boat and permitted boats to operate close to coastal traffic concentrations with little fear of detection for weeks at a time. Unquestionably, Schnorchel was the most effective counter-device developed by the Germans in the Battle of the Atlantic.

[Fifi]

Originally Posted by Aktungbby

. Ultimately, by 1944 and during the invasion, only Uboats so equipped were sent out from the French ports.

According to H.Werner extremely detailed testimony, they sent out even those without snorkel (at this time his own U-Boat didn’t have snorkel)… a following each other by night on surface, with the order to fight incoming planes … they didn’t made it very far and many were very badly damaged.
What’s incredible is they had the suicide order to ram ennemy ships after being out of torp!
H.Werner made it back once more, very luckily.

[Aktungbby]

Indeed. By the time of the invasion the strategic offensive strangulation-blockade of Britain was relegated to an expendible tactical defensive rôle of the Atlantic seawall, incl. kamikaze ramming tactics. The whole U-boat goal was to duplicate Britain's successful blockade of WWI using outdated WWI submarine technology with mediocre "wizard war" technology upgrades. Fuhrer Adoph lived up to his own billing: "at sea I am a coward". The Deutchmarks expended on strategic offset warfare against superior British, US, & Canadian navies was a wa$te: reduced to tactical stop-gap tactics. Only 3-5 % of Allied cargo shipping was ever sunk; hardly meeting the strategic strangulation goals of an Atlantic blockade. The focus was always on the Eastern front, subhuman servitude, and Labensraum. The waste of funds better spent on workhorse Panzer-IV tanks(and Pervitin!) to stem the Red army was wasted on XXI submarines and faulty Jomo-engined jet Me 262's: too little, too late...

[Bilge_Rat]

Back to Bay of Biscay offensive, it looks to me like the preferred method was for U-Boats to travel at high speed day/night.

In OP ENCLOSE II (april 5-13, 1943) majority of U-Boats were detected at night:

5 - 13 April using 86 aircraft. 25 U-boats ran through the same patrol ribbon during the period, the RAF had estimated them to be 28. In 980 flying hours 11 U-boats were detected, for the first time the majority during the night, and 4 boats were attacked. U-376 was sunk and U-465 was damaged. Even with fewer aircraft and less hours the results were almost the same as in the previous operation.

i.e. 25 crossed the area, 11 (44%) were detected, 4 (16%) were attacked and 2 (8%) sunk/damaged.

and even with massive Allied Air coverage, majority of U-Boats went undetected.

OP DERANGE

Operation Derange was a larger-scale version of Enclose II with a larger patrol area between 8 ½ and 12 degrees west. It began on 13 April and was to continue until decided otherwise. Coastal Command used 131 aircraft, its entire available fleet in the operations, only some of which equipped with Leigh Light and 10cm radar.

To the end of April 81 U-boats crossed the Derange ribbon, either outbound or inbound. The RAF aircraft flew 2,593 day and night flying hours. 36 U-boats were located and 22 of them were attacked. One U-boat was sunk (U-332) and two outward bound boats (U-566 and U-437) so badly damaged that they had to abort their patrol.

https://uboat.net/history/fight_back_order.htm

note the stats, 81 U-Boats crossed the area from 13 to 31 april 43, 36 were detected (44%) , 22 were attacked (27%) and 3 were heavily damaged/sunk (4%), so traveling at high speed on the surface and clearing the area as quickly as possible was still the safest course of action.