The Hemlington Nautical History Society

According to the compact Oxford English dictionary the word "Beaver" means:
• noun (pl. same or beavers) 1 a large semiaquatic rodent noted for gnawing through trees in order to make dams. 2 a hat made of felted beaver fur. 3 a very hard-working person.
• verb (often beaver away) informal work hard.
— ORIGIN Old English.

Now the German for Beaver is "Biber" and here starts the story of one of the most forgotten ships in history, the "Biber mini sub"

The 'Beaver' was the brainchild of a young naval officer, Korvettenkapitän (Commander) Hans Bartels. It was based on a captured British midget of the 'Welman' type and constructed by the Flenderweke at Lübeck with notable speed: the first briefing conference took place on 4 February 1944, the first prototype (nick-narned 'Adam') was ready on 15 March and, after trials, it was accepted by the Kriegsmarine on 29 March.

The Biber was a one man Midget submarine or U boat. Its only form of ammunition was two torpedoes specially designed for the sub or two mines, or of course one of each. The torpedo had a reduced number of batteries in it, this of course was to give the torpedo a specific gravity of zero This of course was needed so as not to sink the sub permanently. Of course with limited power there was a reduction in the speed and distance of the torpedo, it is said the torpedo would travel around 5000 yards at a speed of around 20 knots. It may seem slow and a short distance but one has to remember we are talking a small, in fact minuet submersible with one driver who had volunteered for the job in the first place, So distance was not too worrying as his vision was often impaired by ice on the window of the sub. And a periscope that could only see 40 degree either way and straight ahead but not behind. The torpedo was packed with 600kg of dynamite and that was enough to pay end to a lot of ships.

The Biber was powered by an 32hp, 6cyl 2.5 litre Opel-Blitz truck petrol engine; It was a design that warranted a diesel engine but unfortunately no diesel engine small enough was made then. This in itself caused problems, The output of the engine was such it would travel depending on which report you read between 100 and 130 miles at 6.5 knots on the surface and 8.6 miles at 5 knots submerged. She had a fuel tank with the capacity to hold 26 gallons of petrol. Its maximum surface travelling time was 20 to 24 hours though they have been recorded at a lot longer time. Obvious problems with such an arrangement are obvious now and this will become clear later in the piece.

As well as opel petrol engine the Biber had a Battery with an output of 56 volts. capable of speeding the sub on surface at a speed of 4 to 5 knots, but underwater on battery was a slow 2 to 3 knots. The battery gave the sub a maximum travel time of between 2-3 hours.

The total length of the sub was 29' 9". weighing in at 3.5 tons with torpedoes. giving it a surface displacement of 6 tones with torpedoes.

The Biber was built in three sections The bow section was a diving tank, and the aft section of the ship was the aft diving tank. The centre section was the driver’s compartment. The three sections where bolted together with possibly a seal made from card or a compound, It is not verified as to how it was sealed.

The sub was made from 3mm sheet steel, with a 28” coning tower for the drivers head to see where he was going and gain entry to the sub. The coning tower was made from cast aluminium or aluminium alloy. The magnets for the projector compass were housed at the top of a sealed bronze-alloy tube, rigidly fixed through the forward end of the conning tower. It extends some 18” above and 12” below the deck. There was a wooden rudder and single wooden hydroplane. These were controlled by two circular control wheels, one slightly smaller in diameter both turning on the same axis in front of the driver. The air intake was originally 1’ above the conning tower, but this was increased to 3’ and was secured to the periscope. Like the Seehund the air drawn in goes through the crew area first and then to the engine. Therefore it also acts as a fresh air source for both the engine and the crewman.

The Biber while said to be a great manageable sub and easy to drive had no compensating or trimming tanks. One ex driver of the Biber said it was like a young mans sports car, And all volanteers loved them. It had a safe diving depth of 60 foot, (Acording to crew reports and salvaged Bibers the depth gage went to 25 meters or 82 feet)

Like it was mentioned earlier the Biber had a periscope in frount of the driver, it had a round vision of 40 degree but no rear vision was available, This was a obvious design fault as it was common for the Biber to be attacked from behind by enemy aircraft and the driver would not see it till too late. It was also said it was difficult to keep the Biber at periscope depth due to too many things that needed to be done in order to keep it level. The torpedos could be fired while submerged but most times the Biber was just pointed at its target and fired from surface. On captured Bibers the torpedo was set to 10’ depth.

THE LESS PLEASANT, PERSONAL DETAILS
(A ”KLINKER-FREE DIET” AND WORSE)
[For the unenlightened reader there was no toilet aboard WWII German midget U-boats and manned torpedoes. Biber sorties would last from 1-2 days. And the later, Seehund sorties would usually last up to about five days – but one went 10 days.] Before sailing, Biber crewmen received a special, [low-bulk or ”klinker-free”] diet: [then, when on their mission] they were instructed that during the first 24 hours they must use food tablets; thereafter energy tablets, which will keep a man going for another 24 hours. Many Biber crew suffer from seasickness and, owing to the danger of water entering when the hatch is opened, have vomited into the bilge. [This latter unpleasantness must be mentioned because the first symptom of nausea from CO poisoning feels exactly like being seasick. But with CO poisoning, confusion, unconsciousness, and death soon follows.] Not all of the Biber drivers (but most) had been driving submarines before. Many of them were volunteers having served in different units of the German Navy. It’s correct that the drivers got some ”food-tablets.” But ”doping” was only an experiment (D-IX tablets were a combination of Pervitin, Kodain and Eukodal).* To avoid tiredness they ate ”Schoka-Kola”** a type of chocolate, tasting like Cola.

Most of the volunteers did not return from any mission they went on, There was a big and major problem with the Biber and that was mnost of the drivers died from Carbon manoxide poisoning, Or they froze to death.

The following is a list of the midget subs operations, Please note the number of Bibers sent out and the returning ones, not a good record at all, in fact it was said at one time the driver was not expected to return but this was refuted by surviving drivers as untrue.

Midget submarine operations
K-Flotille 261 consisting of 20 Biber one-man submarines, commanded by Korvettenkapitän Hans Bartels arrived eventually at Fecamp (Belgium) 28 August 1944.
29/30: August 18 Biber sailed, all eighteen returned safely. Claims of a landing ship and a Liberty ship sunk were not substantiated by Allied records and no official reference of the attack.
August 31: K-Flotille 261 forced to abandon Fecamp. Most of the Biber were destroyed and abandoned and those which were taken away were subsequently destroyed in a night action with an Allied armoured column. This marked the end of K-Verband operations in Normandy.
An advanced base was prepared at Poortershavn and Hellevoetsluis at the head of the Waal/Maas estuary. The main base being Rotterdam. 30 Biber and 30 Molch were sent here. A further 60 Molch and 30 Biber were sent to Assens from Heligoland and Groningen respectively. 60 more Biber would arrive in the area in January 1945.
22/23 December 1944 - 18 Biber sailed from Poortershavn and Hellevoetsluis. This operation ended in failure. British MTBs surprised the Biber whilst still being towed and instantly sank four. One was mined and one returned damaged. The remaining 12 disappeared. One success - Alan a Dale 4,700 ton - sunk.
23/24 December 1944 - 11 Biber sailed - none returned.
24/25 December 1944 - 3 Biber sailed - none returned.
By the end of 1944 - 31 (thirty-one) Biber lost in return for one merchant ship sunk. Only 8 (eight) of the Biber lost were claimed by the Allies.
27 December 1944: - 14 Biber preparing to sail. Two torpedoes accidentally fired into the lock, 11 (eleven) Biber destroyed. Remaining 3 (three) sailed - none returned but Biber 90 found drifting off the North Foreland on 29 December by HMS Ready with the operator dead at the controls. It was attempted to tow this Biber to Dover but due to deteriorating weather the Biber sank . On its recovery 10 (ten) days later a post mortem on the operator established that he had died from carbon monoxide poisoning.
At the end of 1944 only 20 (twenty) Biber remained at Rotterdam
29/30 January 1945 - 15 (fifteen) Biber sailed from Hellevoetsluis
One sunk following collision with floating ice.
Five forced to return with ice damage.
One found beached downstream from Hellevoetsluis after spending
64 (sixty-four) hours at sea looking for a target.
Five failed to return.
3 February 1945 Both the Molch and Biber depots attacked by air - no Biber losses. Damage to installations prevented anymore operations in February.
Summary of K-Verband operations in January and February shows that during the former month there were 15 (fifteen) sorties and 10 (ten) losses and during the latter month 14 (fourteen) sorties and 6 (six) losses - no successes in terms of Allied ships lost or damaged were achieved in either month.
6 March 1945 - Hellevoetsluis, another torpedo accident - 14 (fourteen) Biber sunk and 9 (nine) damaged. 6 March 1945 - 11 (eleven) Biber sailed - none returned.
One captured by an ML off Breskens.
Four found abandoned along the coast at North Beveland, Knocke
Domberg and Zeebrugge.
One sunk by gunfire off Westkapelle on 8 March.
Five vanished.
11/12 March 1945 - 15 (fifteen) Biber and 14 Molch, S-Boote and Linsen.
13 (thirteen) Biber failed to return and 9 Molch.
2 sank by RAF Swordfish off Schouwen on 11 March.
4 sank by Mls off Westkapelle.
4 sank by shore batteries of Flushing and Breskens on 12 March.
1 sank by Spitfire off Walcheren on 12 March.
1 sank by HMS Retalick at 0325 on 13 March.
23/24 March 1945 - 16 (sixteen) Biber left Hellevoetsluis for the Scheldt.
7 (seven) returned.
4 sank by HMS Retalick.
1 abandoned on Schouwen.
1 sank by Beaufighter of 254 Squadron off Goree.
Fates of the remainder unknown.
Summary of March 1945
56 (fifty six) sorties by Biber/Molch 42 (forty two) craft lost for no result.
April 1945 - Only 24 (twenty-four) Biber remaining at Rotterdam. 60 (sixty) Molch held in reserve at Ammersfoort. Four more operation took place in April involving 24 (twenty-four) Biber - 19 (nineteen) lost - no Allied vessels sunk or damaged in these operations.
Biber and Molch units were also deployed to Denmark and Norway. Kapitän zur See Fritz Boehm assumed command of units in Denmark and Norway but this command later divided between Kapitän zur See Duwel(later to be replaced by Kapitän zur See Brandi) in Denmark and Kapitän zur See Beck in Norway.
Disposition of K-Verband units, Norway and Denmark November 1944
Location Unit
Northern Norway 60 Biber, 60 Molch
Southern Norway 60 Molch
Denmark 60 Biber, 60 Molch, 12 Hecht.
Heligoland 30 Molch
Borkum 30 Molch
Ems Estuary 30 Biber.
K-Flotilla 265 dispatched to Harstad in Norway - November 1944.

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sources:
http://www.askoxford.com/concise_oed/beaver?view=uk
http://uboat.net/ops/midget.htm
http://www.juergenthuro.de/html/the_beaver.html