Underwaterweaponry of S-Boats of the Bundesmarine

The main-weaponry of the S-boats of classes 140, 141, 142, 149, 152, and 153 consisted of torpedoes.

The  six boats of class 149 and the two school-boats "UW 10" (ex S 130, ex FPB 5130) and "UW 11" (ex S 208, ex FPB 5208) were armed in 1956/1957 with to turnable torpedotubes calibre 53,3 cm (21 inch).

S-"Sturmmöwe" with Turnable Torpeotube - Picture: Archives J. Prochnow

"UW 10" and -"UW 11" at Murwik - Picture: Archives K. Scheuch

The boats of classes 140, 141, and 142 were equipped with four torpedotubes (ToRo M 1) of biritish design (Saunders-Roe) with a calibre of 53,3 cm (21 inches) built by Pintsch-Bamag. Ther tubes were arranged diverting 10 degrees (forward) and 15 degrees (aft) from the midshipsline. 

The torpedoes were launched with pressured air of about 130 ATÜ from the tubes. A test in the 2. S-Squadron to launch a torpedo with a charge in the 50es ended with the death of a Kapitänleutnant of the test-personnel. Thereupon the tests were abandoned.

Restored Torpeotube of "Kranich" in the Navalk Museum - Picture: Hartmut Klose

The tube was a welded construction of aluminum with different added parts e.g. pressured air bottle, winch to load the torpedo and differnt equipment to ajust the torpedo in the tube. Since besides of the torpedoes mainly bought from France from old German WW-II-stocks  "G 7 a" also the British torpedoes "Mark 8" were to be launched from the torpedotubes the standard torpedotube was mounted with double adjusting equipment for course-stability, depth, holding bolt und start-lever.

Behind the tube were storage- and loadingrails in which the torpedoes were placed when loading and then with help of a wire-cable and a winch could be pulled into the tube The loadingrails also were used tio carry spare-torpedoes, which could be loaded into tubes that had become free after launch of a torpedo.

Since the space behind the aft tubes was not suitable for long loadingrails there was a turnable loading stand in the middle ob the aft deck which was utilized to load both of the aft tubes.

For exercises it was sometimes ordered to carry a seventh torpedo, what obstructed the access to the emergency-rudder-room (compartment 1).

Torpedo "G 7 a"

From French stocks (leftovers of Kriegsmarine stocks) Germanx bought since 1957 bigger amounts of WW-II-torpedoes "G 7 a".

"G 7 a" was a development of Reichsmarine and into use of the fleet in 1934. It had a calibre of 21 inches (= 533 mm - and therefore got the letter "G" in its type-designator). Its length was 7,14 m (rounded off 7 m and therefore the figure "7"). Since it was the first torpedo developped with thís calibre it got the letter "a" in its type designator. It was developped with a steam-gas-motor on the basis of the British Brotherhood-Machine.

The steam-gas-motor turned two contrarotating propellers via a gearbox so that the toropedo would not turned in the water by the effects of a single propeller.

A two-gyro-system kept the course cranked in via the siderudders. The depthrudders were controlled by the depthrudder-apparatus. In contrary to the British torpedo side-rudders and depth-rudders were situated behind the contrarotating propellers.

Tailend of a "G 7 a" - Picture: Wikipedia

The "G 7 a" was used by the Bundemarine and the navies of Denmark, Norway, and Spain until the early 70es.

The torpedo had a battle-weight of 1538 kg, its steam-gas-motor was driven by petroleum and provided a speed of 44 kts, it had a range of 6 km, at a speed of 30 kts of 12 km.

Torpedo G 7 a - Drawig: Wikipedia

The warhead contained 280 kg schooting-wool and was ignated by contact- or magnetic distance detonator.

The torpedo had no possibility to detect the target, it was a straight-runner which with functioning gyros kept the course cranked in at the launching.

Contrary to the warhed of "G 7 a", which was painted in olive green, the exerciseheads were painted with white and red stripes in longitudinal direction. In stead of the detonator device in the exercise-version there was a head-lamp for night-firings which made the crossing of target-course better visible and permitted to follow the torpedo in order to fish it up at the end of its range.

Exercise-Torpedo "G 7 a" - Picture: Wikipedia

Torpedo "Mark 8"

The torpedo "Mark 8" was developed during the 20es of the last century in England and was the standard torpedo of the Royal Navy during World War II. The Federal Navy bought it from stoks of the Royal Navy and launched it from the Pinsch Bamag tubes.

It also was a steam-gas-torpedo of a length of calibre 21 inches (533 mm) at a length of 6579 mm. Its weight was 1566 kg andthe warhead contained 365 kg Torpex. The torpedo "Mark 8" had a range of 6400 m at a speed of 41 kts and 4570 m at a speed of 45 kts.

Since cranking in depth and settings for the straight-running-apparatus was to be performed at different positions of the torpedo than at "G 7 a", the torpedotube have adjustable for the setting-gear which had to be remounted depending on torpedo to lauch.

"Mark 8"-Launching from Tube Rohr III - Picture: Archives B. Etzold

Otherwize costruction and technic were almost identical with "G 7 a". Optical the two torpedoes were to be differentiated in as much as  the "G 7 a" had its side- and depth-rudders behind to to controrotating propellers, the "Mk 8" before them. The lower half of tht exercise-head was painted red, the upper part white. It also has a headlamp for night-exercise-firings.

The last firing of a "Mark 8"-exercisetorpedo by the Bundesmarine was performed on 12.06.1975.

The Last "Mk 8" on the Quarterdeck of Tender "Elbe" - Picture: Archives B. Etzold

The Squadron-Kommander,  FKpt Giermann, reported:

Loading S-"Kranich" at Mürwik with Wartorpedoes "Mk 8" - Picture: U. Grothe

Both "G  7 a" and "Mark 8" were not directable, i.e. they coud niot be influenced after firing and could  not detect the target by themselves. After diving in which was deeper depending on firing unit's speed the torpedo was ssteered to the depth input before firing. The two-gyro-steering-system ws used for angle firings. Mostly it served to compensate the angle between course of the boat when firing and the angle of the torperdotube with respect to the midshiopsline, i.e. that e.g tjhe torpedo fired from the posrt forward tube had to chenge its course by 10 degrees to starboard and then to continue with the boats' course when firing.

Torpedo "DM 2 A 1"

Since both torpedoes "G 7 a" and "Mk 8" necitated to approach close to the engaged target in order to achieve a hit with the straightrunners, ordered by the German Navy the company STN Atlas worked to develop a new wireguided torpedo.

The torpedo developed by STN Atlas with the indicator "DM 2" hada calibre of 533 mm and a length of 6,08 m. The enhanced version "DM 2  A 1" "SEAL" (also known as Seeaal) was 6,55 m long. 1967/68 the first trials on board were carried out with boats "Wilhelm Laudahn" (ex S-"Seeschwalbe") and S-"Kormoran".

The torpedo was fired from torpedotubes directed aft and propelled by a zinc-silver-battery, what made optical detectablilty by the enemy almost impossible. The torpedo was driven by two counter-rotating propellers at a speed of 33 kts. The range was 20 km.

Loading a SEAL-Torpedo - Picture: H. Soltau

Via the control-cable, 18,5 km long half of which unwinding from the torpedo the other half from the tube, not only the course but also the depth of the torpedo could be changed by the operator at the torpedo-firecontrol-console (Torpedo-Feuerleit-Anlage) AH 7020-A3 (short: TKG) on the firing boat.

Torpedo DM 2 A1 (SEAL)at the Navy Museum - Picture: kriegsschiffe.net

The torpedo reported speed, course, unwinded cable-length and depth of the torpedo, so that the operator at the TKG could correct it if necessary. The passiv searching head of the torpedo reported the bearing of the engaged target. When the cable was interrupted or the end of the cable was reached the torpedo switched to an active modus so that a hitprobabilty of 90 % was achieved.

The warhed contained 250 kg TNT and was equipped with a distance- and an impact-detonator.

S-"Ozelot" with the new Torpedotubes - Picture: Archives K. Scheuch

S-"Puma" with the Tubes for SEAL - Picture: Archives K.Scheuch

Torpedotubes and Torpedo Launchingracks of the Testboats

The two boats of class 152,"Hugin " and "Munin", were commissioned as test vehicles in  1960. The trials were performed with one gun and two torpeotubes, with one gun and four torpeodtubes, and with two guns and four torpeodtubes. Finally the boats got four torpedotubes aof Norwegian origin for firing torpedoes §G 7 a" without "spoons" and two Bofors40/L70 MEL.

S-"Munin" with two Torpedotubes and one Bofors - Picture: Archives J. Prochnow

S-"Munin" with four Torpedotubes and two Bofors - Picture: Archives J. Prochnow

Thie two testvehicles from England, S-„Strahl“ (P 6194) of the English type „Brave“ and S-„Pfeil“ (P 6193) of the English type „Ferocity“ were commissioned in 1962. These boats werde tested without, weith one and with two guns as wellas wiith two and four torpedo-launching-racks. In the end they were equipped with two gun Bofors  40mm/L70 MEL and vier Lauching-racks.

S-"Strahl" with one Gun and two Launching Racks - Picture: Archives J. Prochnow

S-"Pfeil" with one Gun and four Launching Racks - Picture: Archives J. Prochnow

Torpedo-Aimingpillar and RZA 5b

The aimingpillar of company Hagenuk, Kiel, employed on boats of the Bundesmarine was a further depelopment of the aimingpillar for S-boats already employed by the Kriegsmarine.

One of the additional function was the posssibility to choose four-torpedo-fan "Viererfächer", since the boats of classes 140, 141, and 142 were equipped with four torpedotubes.

The torpedo-aimingpillar was situated in the middle of the open bridge and the tube-aiming-gadget (Rohrzielapparat) RZA 5b of company Carl Zeiss - also a further development of the RZA 5 employed by the Kriegsmarine- was arranged to look over the windshield of the bridge, so that the marksman could aim at the target unhindered.

On the aimingpillar the electrical connectors were mounted for transmission of the selected method of firing - single shot, two-torpedo-fan forward, two-torpedo-fan aft, and four- torpedo-fan - as well as inputs for the torpedo-depth and data for the straightrun-apparatus like spreadingangle for fan-firings, and compensation for the paralaxis caused by the position of the tubes. 

Torpedo-Aimingpillar with RZA 5b - Picture: Archives K. Scheuch

Views of the Torpedo-Aimingpillar of S-"Kranich" - Pictures: H. Klose

 On top of the pillar was a turnable pedestal mounted for the tube-aiming-gadget, which was turned by a wheel on the frontside of the pillar. How much the pedestal was turned out of the middle-axis of the boat was shown on an indicator over the wheel.

On the portside (left side) of the pillar dials were arranged for the "zero-notch" of the pedestal, for the light of the RZA, for the electromotors, and connectors for electricity and for the synchros red ans stat. 

On the starboardside of the pillar were the dials for "zero-notch" on and off, the dimmer for the RZA lights, the galvonometer, and the electrical firing right.

The RZA 5b consisted of the mechanical lead angle computer with the inputs enemy bow left or right, for enemy bearing angle,enemy speed, and torpedo speed. The optical sight on top the RZA was turned to the computed lead angle, so that by turning the boat to the friring course the cross hairs pointed at the target.

TZS und RZA 5b von S-."Kranich" - Foto: H. Klose  

The spread angle input determined the angular distance between the torpedoes  in a fan. At a firing range of 1000 m on degree resulted in 19 m, at 4000 m an area of 456 m width was covered on the course-line of the target with a fofur-torpedo-fan.

The oculars could be influenced by vrious filters.

On the two handles at the oculars the firing buttons were arranged with a security cap. The torpedo(es) was/were fired electrically from the selected tube(s) by pressing the button(s).

Tube-Aiming-Apparatus (Rohrzielapparat) RZA 5b of S-"Kranich" - Picture: H. Klose

Exercisetorpedo fied from Tube II of S-"Kranich", at the Horizon "Pelworm" - Picture: Archives K.Scheuch

  The boats of classes 152 and 153 were not equipped with torpeod-aimingpillars.  

Anchored Mine at the Navy Museum - Picture: Archives K. Scheuch

Anchored mines consist of a minecarrier or anchor, which sink to the bottom of the sea, and a minereceptacle with a cable, which is fastened at the anchor, and swims under the surface of the sea. Anchored mines normally are fitted with mechanical detonators and explode by a touching ship. In larger depth anchored mines can be used against submarines. Anchored mines arethe oldest type of mines employed in bigger numbers. The first anchred mines were already emploed 18913 off Fort Hudson and Fort Richmond. The minebarriers of WW-I were consisting of anchored mines, the ones of WW-II  in their majority and also during the Cold War and in regional conflicts after 1945 anchored mines were planned to be used and also were used.

Exercise Bottom Mines on a S-Boat - Picture: Archives K. Scheuch

Already during WW-I bottom mines were developed and employed. Bottom mines are remotely ignited, their destruction potential is based upon the gas- and foam bubble originating from the detonatioiin which first lifts up the ship's hull. When the bubble reaches the surface of the sea it looses its pressure, a vaccum is developing under the ship and the bearing effect of the water disappeares in this area. The impacted area is actually lifted up in a shock and then it falls down,  what results in heavy personnel losses. Frequently it results in the ship breaking apart with a total loss of the ship.

Depth Charges

The reason why S-boats carried depth charges is to be seen in WW-II. The S-boats of those days passed the bows of ships in close proximity and dropped depth charges with detonation in low depth. The detonation damaged or sank the ship, the S-boat was unharmed because of teh distance to the detonation caused by its high speed. 

This methode could, however, only be used in case of unarmed ships or ships unable to defend themselves. 

Also it was still believed, that S-boats could play a role in anti-submarine warfare. After som years it was realized that without  acoustic intercept installation and sonar the chances for success were minimal, therefore the depth charges were taken off the boats some years after their commissioning.