Upon the end of the danger of icing on Schelde river the 3. SFltl transferred from Ostend to Rotterdam. On February 25th 1941 "S 30" and "S 33" of the 2. SFllt lay stopped about 12 nm north of Lowestoft when they detected the northbound coastal convoi FN.417. They fired two torpedoes each. Both missed their targets. "S 30" (Oblt.z.S. Klaus Feldt) reloaded and fired a torpedo on the Hunt-Class destroyer dscort HMS "Exmoor". The hit caused a big explosion in the aft part of the ship and she sank immediately. 104 crew-members including the commanding officer, Kaptlt. R.T. Lampard, were killed in action. More than 40 survivors could be rescued by the sloop HMS “Shearwater” and a trawler. Oblt.z.S. Feldt was awarded the Knight’s Cross (Ritterkreuz). The Wreck of “Exmoor” is laying at a waterdepth of 33 m in position 52^o 30’ 16’’N 002^o 05’E. Since 2006 the wreck is protected by the Protection of Military Remains Act of 1986 as a “Protected Place”. 

Sinking the "Exmoor" caused the convoi to change course, so that neither the 2. nor the 3. SFltl could launch further torpedoes. The 1. SFltl operated further to the north and "S 28" could sink the steamship "Minorca" (1123 BRT) by torpedo.

Thereafter the boats had to stay in harbour due to bad weather. Not earlier than on April 28th 1941 the 1. SFltl could lay a mine-barrier again. Thereafter they attacked a convoy of 57 ships. "S 26" and "S 29" believed to have sunk three ships with a total of  9.500 BRT, sunken was the British steamship "Ambrose Fleming" (1555 BRT). On 29.04.1941 "S 39" and "S 40" collided. The boats were taken under fire by destroyers and came  into a gun fight with British MGBs. The 3. SFltl laid a barrier off Hammond Knoll with four boats. On their way back the pair "S 61" and "S 58" run into a gun fight with the British  MGBs 61 and 59.

Also May 1941 brought many gales. The boats were stuck in their harbours. During an attempt to carry out a mining operation off the British coast on 18.05.1941, the mines tore themselves loose and caused damage to the boats.

On May 23rd 1941 the 1. SFltl, on May 25th 1941 the 2. SFltl and on May 27th 1941 the 3. SFltl transferred to Kiel in preparation of the operation "Barbarossa", where the last boats secured on May 28th 1941.

After withdrawal of the 1., 2. and 3. SFltl only the 4. SFltl remained in the western area. On June 1sr 1941 it was configured as follows:

With that a S-boat warfare on the level performed hitherto was no longer possible. On June 2nd 1941 the flotilla left harbour to operate on an aircraft carrier reported by the Luftwaffe. They bumped into a "big ship" escorted by a destroyer and several minesweepers. "S 22" fired two torpedoes, "S 19" three, "S 24" one, and "S 20" two, a total of eight torpedo. They were taken under fire by the sloop "Kittiwake". The big ship was "Tender C" a merchant ship of 7924 BRT retrofitted to a fake-aircraft carrier, it was hit and had to be abandoned. Bätge declaired the high expenditure of torpedos with firing at a probable barrier bracker.

On May 6th and 10th 1941 the boats laid mines, on which the British freighters "Gasfire" (3001 BRT) and "Kenneth Hawksfield" (1546 BRT) sank on June 21st 1941. Due to bad weather the next sortie was not possible earlier than during the night June 16th/17th 1941 with boats "S 202, "S 24", and "S 25". They laid mines at buoy 57 on which the British freight steamer "Hull Trader" (717 BRT) sank on June 23rd 1941. On their way back they stopped two Netherlands air force officers, who tried to escape to England with their canoe.

Bad weather permitted the next operation not earlier than on June 19th 1941. "S 22" and "S 20" laid mines on the convoy route and were involved in a gun fight with three MGBs.

On June 24th 1941 the 4. SFltl transferred to Cherbourg. The operations on Jue 25th and  28th 1941 were without results.

On July 6th 1941 "S 107"  was commissioned by Oblt.z.S. Wilcke, on July 11th  "S 49" (Lt.z.S. Max Günther) and on July 25th "S 50" (Lt.z.S. Karcher) were commissioned after Oblt.z.S. von Mirbach already on June 20th 1941 had commissioned "S 48" and had conducted the first operation with her in the night to July 6th 1941.

In the night to July 10th "S 22", "S 19", "S 48", and "S 20" laid 24 TMA in the sea-area south of the Isle of Wight and dogged around with two destroyers. In the night to July 23rd the flotilla laid 18 TMA and four tearbouys south of Portland Bill and was taken under heavy fire by British coastal artillery.

On July 26th the new "S 49" (Oblt.z.S. Karcher) arrived at Boulogne together with two R-boats. She stayed there since the 4. SFllt was to transfer to Boulogne end of July. 

During another mining action on the convoy-route between the Isle of Wight and Portland Bill the four boats laid another 18 TMA, with that the flotilla had laid a total of 155 TMA and 20 tearbouys in eight nights until July 29th 1941 without any noteworthy incidents.

On July 29th 1941 the flotilla transferred back to Boulogne. From there short sorties were conducted into the pass of the Channel with support of Funkmeßstelle Wimereux (radar site). 

On August 7th 1941"S 49", "S 19", "S 48" and "S 20"  left harbour to attack a convoy of five freighters, some escorts and two destroyers reported south of Folkestone. All fired torpedoes went wrong, only "S 48" (Oblt.z.S. von Mirbach) thought to have sinked a freighter of 4000 BRT which could not be confirmed.

"S 19" was dismissed and marched to Kiel. On her march she was attacked by a fighter with airweapons, one sailor was wounded. The aircraft was shot down and fell burning into the sea.

A further new construction for the flotilla was "S 51", commissioned on August 8th 1941.

On August 9th boats "S 107" and "S 50" transitted from Rotterdam to Boulogne. "S 107" had a rudder malfunction and was towed in to Calais by picket "V 1512" where she was docked. 

On August 190th 1941 "S 49", "S 20" aund "S 48" left Boulogne for an attack against a reported convoy off Dover. Although the visibility was poor they could find the convoy because of position-reports by a Freya-Funkmeßgerät. "S 49" torpedoed the British Freighter "Sir Rusell" (1548 BRT). The ship broke apart. Reloading was not possible because the torpedoes jammed. "S 20" fired on a freighter of 4000 BRT and heard a detonation. A destroyer of Hunt-class and other escorts repelled the boats, which singly returned to Boulogne in the early morning hours. They had more than once been tracked by British radarstations.

After transit of the flotilla to Rotterdam on August 17th 1941 "S 49", "S 20", "S 48" and "S 51" operated on 19.08. against a convoy off Orfordness. "S 48" sank the Polish freighter "Czestochowa" (1971 BRT) and torpedoed the believed tanker of 5000 BRT, the British freighter "Dalewood" (2774 BRT) which could be towed in. "S 20" missed a British destroyer with two torpedoes.

Sorties of the  4. SFltl with four boats and of the 2. SFltl also with four boats during the night August 19th/20th against a nothbound convoy was without results. 

On August 22nd 1941 "S 20" was ordered to transit to Kiel where she was handed over to the 6. SFltl as a training-vessel.

In his "Erinnerungen an den Schnellbootseinsatz im Westen 1940 - 1945" (Memories of the S-Boat-Operations in the West 1940 - 1945) of the former A op in the staff of F.d.S., Kaptlt. a.D. Bernd Rebensburg, he writes: "Already in falle 1940, about August, F.d.T. believed from decifering to be able to prove that from the Isle of Wight and from the cliffs of Dover and between Felixstowe and Great Yarmouth radardetections of our S-boats had been made out to 30 nm also if that were caused by seldom overranges. The normal ranges of the coatal radarstatione could be determined with the UK-Systems of our S-boats...."

The next actions on September 1st and 2nd with "S 48", "S 49", "S 50", "S 51" and"S 107" and on Septzember 3trd an 4th with the same boats plus "S 52" (Oblt.z.S. Karl Müller") were without results. 

On September 9th 1941 the boats "S 48", "S 49",  "S 50", "S 51", and "S 109" had a chance to shoot.  They believed to have sunk five freighters with a total of 13.500 BRT, but only the British freighter "Duncarron" (478 BRT) and the Norwegian freighter "Eikhaug" (1436 BRT) sank.

During the night Septemer 17th/18th 1941 the flotilla believed to have sunk four merchant ships with a total of 25000 BRT, the real success was much lower, "S 50" torpedoed the British steamer "Tetela", "S 51" sank the British steamer "Teddington" (4762 BRT). 

There followed two resultless sorties during the nights September 26th/27th 1941 and 29th/30th. On the march back a bomb fell so close to "S 50", that the engine foundations were torn apart.

A sortie on October 2nd 1941 was without result. On October 3rd 1941 the RAF attacked the harbour of Rotterdam. "S 107" was damaged severely and was out of order for eight weeks, "S 51" and "S 52" got away with light damages from debris. The next sortie took place with the newly commissioned "S 109" (Lt.z.S. Bosse), "S 49", and "S 52" on October 12th 1941. Again a destroyer was sighted, which instantaniously took the boats under fire.

Upon the end of the operations of the 1., 2., and 3. SFltl in the Baltic Sea all boats were "ready for the ship yard", i.e. they were not ordered back to the western front. The 1. SFltl was to transfer to the Black Sea after the time in the ship yard, the 3. SFltl to the Mediterranean Sea.

The 2. SFltl (Kptlt. Feldt) transferred back from Kiel to Gruppe West at the end of the shipyard repairs on 01.10.1941 in two groups with a total of six boats. The boats "S 42", "S 44", "S 45", and "S 46" were to join the newly formed 8. SFltl after a total overhaul. On October 9th 1941 the 2. SFltl was laying in Rotterdam with the following structure:

On October 11th 1941 the Staff of the F.d.T. arrived at Scheveningen after 5 months of action in the Baltic area and controlled from there the S-boats, KKpt. Petersen was officially still commander of the 2. SFltl, but was acting as second in command of F.d.T.. The 2. SFltl was commanded by Kptlt. Feldt. 

On October 12th 1941 the 2. SFltl left harbour for the first operation, they bumped into a convoy and while the first group run gun fights with escorts, "S 41", "S 53", and "S 105" had a chance to shoot. They believed to have eliminated six merchant ships with a total of 18.000 BRT, the real result was: "S 53" sank the Norwegian freighter "Roy" (1768 BRT) and "S 105" sank the British freighter "Chevington" (1537 BRT). The tactic used during this attack was awarded by the F.d.S. and recommended to the other flotillas. The 4. SFltl had taken a lurking position on a convoy route but did not see any enemies.

The German press published the two articles below with respect to this attack of the 2, S-Floila and its supposed success.

On October 20th 1941 KKpt. Petersen handed over command of the 2. SFltl toKptlt. FEld.

During the following days bad weather was prevailing, the two flotillas lay in their bunkers. On October 25th 1941 a convoy was reported, both flotillas left harbour, but had to return because of bad weather. Similarly it happened to the two flotillas on November 4th 1941. From November 5th to 11th 1941 the weather kept boats in harbour again. On November 12th 1941 the next sortie of the 2. SFltl occurred, which again had to be broken off due to bad weather. 

On November 18th 1941 a significant innovation for the S-boats by interaction of the F.d.T. the so called "Schnepfentafel" was introduced. The method used hitherto with the key "M" had in the past months proven as too troublesom and had caused considerable delays in the communication during actions.                      

The Schnepfentafel was only determined for guiding S-Boats in operations in the Channel and along the English eastcoast and was only for the use on the S-Boot-Welle (S-Boat-Channel). 

With Schnepfentafel (short for Marine Dienstvorschrift 79 - MDV 79 - "Signaltafel Schnepfe") 174 four- letter codes for fighting-signals ("Destroyer from north" of "Am fighting with"), for course- and speedreports (e.g. "Heading northwest" or "Full speed"), for geographic points resp. quadrants (e.g. "Buoy 54F" or "Humber lightvessel"), for times and figures (e.g. "20 o'clock or 0 - 9) and for addresses and signatures (e.g. "F.d.S." or "C-Fltl 3. Gruppe") were used. A combined message "Northbound Convoy at 01.00 o'clock at bouy 54A" could thus be transmitted unencoded.

For each operation one of 10 of the watersoluble pages of a Schnepfentafel was used three times and was then destroyed. Which page (which table) had to be used and, therefore, was permitted to be taken out at sea for an operation was ordered at the pre-action-briefing. This procedure made sure, that the British Intelligence could not decipher the reports made by the F.d.S. to the boats and vice versa.

Details of Signaltable Schnepfe can be studied in "Historischen Marinearchiv" contributed by FKpt a.D. Urs Heßling: