|S-Boats in the Kriegsmarine - Armament|
S-Boats in the Kriegsmarine 1935 - 1945
The Boats Measurements, Propulsion and Armament
"S 2" - "S 5"
"S 6" - "S 13"
"S 14" - "S 17"
"S 18" - "S 25"
"S 26" - "S 29"
"S 30" - "S 37"
"S 54" - "S 61"
"S 38" - "S 53"
"S 62" - "S 66"
All boats of type "S 38" built later, i.e. "S 67" - "S 99", "S 101"- "S 131", "S 137" - "S 138", were built with shull-cap bridge (Kalotte) and a MG amidships. Almost all boats built earlier were retrofitted with skull-cap bridge during the war.
"S 1362, "S 139" - "S 150", "S 167" - "S 218"
"S 151" - "S 158"
"S 219" - "S 300"
"S 30" - "S 500", "S 701" - "S 800"
"S 701" - "S 800"
The main-weapon of the S-boats was the 53,3 cm torpedo. Up til S 25 all boats had the torpedotubes mounted unto the back. From "S 26" on the torpedotubes were enclosed in a decked-over forecastle. Behind the tubes cradles were mounted in order to permit torpedoes to be loaded but also to store sparetorpedoes.
"S 24" with torpedotubes on the back - Picture: Archives Ola Erlandsson
"S 102" in the Black Sea - Picture: Archives Karl F. Künzel
Torpedo-reloading in a Channelharbour - Picture: Archives Enno Brandi
The Torpedo G7a was the standard torpedo of the 2. Worldwar and was introduced into the fleet 1938. It had a length of 7,16 m and a diameter of 53,3 cm. The weight was 1528 kg, a which the warhead had 280 kg of Hexanite. At a torpedo speed of 44 knots the range was 5000 m (2,734 miles), at 40 knots 7500 m (4,101 miles) and at 30 kn 12,500 m (6,835 miles). The power was provided ba a mixture of parafin and compressed air which produced the steam for the pistonmotor. The torpedo produced a good visible bubble-track. The propulsion was inflicted by two propelloers turning in opposite directions in the torpdo's tailend. The tailend also housed the rudders for course and depth. The torpedo had a gyro-controlled steering apparatus.
Until 1942 contact-detonators were used which were unreliable, then the problem was overcome.
From june 1944 wthe S-boats also used the elektrical driven T3d „Dackel“,a torpedo of 11 m length, which at a speed of 9 knots could be fired at a range of more than 30 km into the harbours at the Normandy where they performed a search-pattern until the hit a target or the search was ended.
rom mid 1944 the torpedo T5a „Zaunkönig“ was introduced for the
S-boats. It ws an elctric driven torpedo which carried out an acoustic
steered search pattern. It was 7,20 m g, weighed 1497 kg and had a warhed
of 200 kg. The range at a speed of 22 kn was 4,375 miles.
The targeting device, the Rohrzielapparat 5 (RZA 5) with Zeiss-Optic, was mounted on a targeting-column in the middle of the forward end of the bridge. The RZA 5 was a development of the RZA 3 used unteil S 29. A mechanical targeting computer with three arms (ships direction, angle situation angle and torpedocourse) provided the torpedo-aiming point which was necessary according to the situation angle (Angle between target bearing and target course) and target speed in order to obtain a hit. The targeting column permitted an angle-shot utilizing transmission of the firing-angle to the steering-apparatus in accordance with the direction of the binocular sight using handwheels.
RZA 5 as a Means of Night Recconnaisance
RZA 5 on the Hagenuk Targeting Column
Boats S 701 bis S 709 were equipped with four torpedotubes, two of which were to fire torpedos aft and were meant for the employment of Zaunkönig-torpedoes. These boats could carry a total of eight torpedoes.
Artillery must be considered as the secondary-armament. Originally all boats were equipped with a 7,62mm Bergmann MG 15 which was later substituted by a MG 34. With the outset of the war boats unteil S 37 were equipped with a Rheinmetall 20mm Flak on a single carriage. From 1941 onward this gun was substituted by the improved Model C/38. The rate of fire was approximately 300 rounds/minute, the firing range 4.800 m at 45 degrees elevation.
Rheinmetall 20mm C/38
20mm C/38 in Action on a S-Boat
A/A-Firing of a 20mm-Flak - Picture: Archives K.F. Künzel
The boats of classes "S 38", "S 100" and "S 701" got besides of this a second C/38 Flak in a well on the forecastle. The mount was retractable into the well by demounting the barrel and lowereing the mount via a hinge into the well. The well was covered with a round plate to protect the gun against rain and spray. The gun was later equipped with a "Drehkranzlafette" permitting aiming from 0 to 85 degrees elevation and a traverse of 360 degrees. The ammunition was handed to the gun-crew through a hatch from the compartment below.
Many boats got during the war a 20mm-Twin-Mounted Flak midships.
Since 19544 a small number of boats, thereamong "S 65", were equipped with a 20mm quadriple-mount. This Flak had a high rate of fire but necessitated a handling team of seven to eight men.
Also beginning with the class "S 38" many boats got a 40mm Bofors Flak 28 on the quarterdeck. Some of these guns had a light shield to protect against light shells and splinter. The Bofors-guns were of Swedish design and were the same as the Allied used. Most of the Bofors installed on S-boats were war-loot from France, the Netherlands, Denmark and Norway, they were, however, also delivered by Sweden. Partly the were built in Germany under licence. Also this weapon required a handling team of seven men.
The rate of fire was about 300 rounds/minute, the range was 4.800 m at 45 degrees elevation.
40mm Flak Bofors 28
For the class "S 100" the newly developped Rheinmetall 3,7 cm Flak LM/42 was planned. It was a rapid firing gun with a shield, that could be handled by three to four men and reached a rate of fire of 128 rounds per minute. The range was 10000 m at an elevation of 45 degrees.
For the class "S 219" - also called "S 38B" - as well as for the boats of class "S 701" six Rheinmetall Flak 30mm doublemounted were planned.
3,7 cm guns on boats "S 204" and "S 205" - Picture: Archives Förderverein
The guns were tested on some boats, however, they never got ready for the line, so that while building boats the artillery weapons got installed that were available.
During the war the S-boats were employed as fast clandistine minelayers in almost all warlzones and a great part of the successes against enemy shipping were due to the minefields they layed out.
The boats had a minelayinginstallation on either side of the stern and were able to carry six to eight mines depending on type of mines, without demounting of the torpedo cradles og rigging up minerails instead. The following mines were employed universal mine (Einheitsmine Typ C = EMC), torpedomine type A (Torpedomine Typ A = TMA), torpedomine type B (Torpedomine Typ B = TMB), airmine type A (Luftmine Typ A = LMA), airmine type B (Luftmine Typ B = LMB), antisubmarinemine type A (U-Bootabwehrmine Typ A = UMA), antisubmarinemine type B (U-Bootabwehrmine Typ B = UMB), blasting mine (Sprengboje Typ D = SprBD) and tearing mine (Reißboje = RB).
S-Boote mit aufgeriggten Minenschienen - Foto:
As the TMAs and TMBs, laid off Malta exploded shortly after laying only UMAs and UMBs as well as SprBs and RBs were laid for a time. UMAs and UMBs were moored mines with contactdetonator and a warload of 40 kg, while TMAs and TMBs had magnetic and acoustic detonators.
Loading of UMB - Picture: Archives K.F. Künzel
A boat of the 2. SFltl loaded with UMB beladen at Boulogne 1943 - Pidture from Krakow "Schnellboot in Action"
The S-boats could carry up to eight depth charges on the racks at the stern if no mines were carried. The depth charges could be employed against submarine or with little floating devices attached which reduced sinking speed against chacing surface units. While Hümmelchen and Fochk do not mention them some sources report about hydrophones attached to the hull of the boats which at lower own speed provided detection of other units.
Depth charges on the racks - Picture: Archives K.F. Künzel
Radar an ESM (Funkmeßgeräte)
The Krigsmarine differenciated between active radio detection systems (Funkmeßgeräten mit Ortungsfähigkeit = FuMO = Radar) and passive radio detection (Funkmeßgeräten mit Beobachtung von elektronischen Ausstrahlungen = FuMB = ESM).
But the Krigsmarine S-boats operated mainly against targets which were detected by the landbased radio detection systems (Funkmeßanlagen) and reported by radio.
Although F.d.S. had requested to equip his units with radar (FuMO-Geräten) many times the OKM saw no need for that and gave the big surface units priority.
Therefore, the S-boats primarily were equipped with ESM systems (FuMB-Geräten), radar (FuMO-Geräte) for deploament on S-boats were only developped and tested from 1943 on.
The first radar
being developped for S-boats was FuMO 71 “Lichtensten B/C”, a fixed
antenna of 1,3 x 1,6 m, which covered an angle of 35 degrees from dead
ahead. The range was 1,2 – 3,7 miles (2 bis 6 km). The system was very
accurate and could be used for navigation. It was equipped on the boats in
a limited number since 1943. The system was a development from the
Luftwaffe-system FuG 202.
With a turnable
mast the system was called FuMO 72. Because of the increase of the radar
cross section ogf the boats due to the big antenna it got the nick name
„Granatenempfänger“ (artillery shell collection basket).
In March 1944 the
system FuMO 62 „Hohentwiel S“ was developped and tested for S-boats.
It was based upon the Luftwaffe-system FuG 200 „Hohentwiel“ sea
surveilance radar. It had a bigger range – about 10 km (6,2 Sm) – and
was more precise. But the 1,2 x 1,2 m rotating antenna caused a similar
effect for the radar signature of the boats.
At least two boats – "S 122" and "S 127" – served 1944 as teststations for FuMO 81 „Berlin S“. The system was a development of the Luftwaffen system „Rotterdam“. It was an effective microwave search radar operating on a wavelength of 9cm and at maximum poweroutput of 18 – 20 kW had a range of about 30 km (19 miles). The antenna consisted of four transmitters on rotating plastic rods covered by a plexiglas dome (the forerunner of the today's radomes). None of the FuMO 81-Geräte had so grest successes as the counterparts on British or American boats.
As per Jac J. Baart onlyx the boats "S 130" and "S 701" were equipped with FuMO 81 "Berlin S".
The passive radar detection systems (FuMB-Geräte) for S-boats were not only suited to determine the bearing of enemy radar transmissions but to a certain extent also to determine the range. These systems had the advantage that the opponents could be detected long before they arrived at radar range whithout own emissions giving away the position.
The FuMB Ant 3 "Bali 1" was an antenna which could be used universally in the systems FuMB 29 "Bali-Anlage", FuMB 4 "Samos" Empfänger 90 - 470 MHz), FuMB 9 (146 - 264 MHz) and FuMB 10 "Borkum" (100 - 400 MHz. The signals detected were passed on to a radar detection addition-oszillator (Funkmeßzusatz-Oszillator = FuMZ 1) for evaluation by the operator.
A radar detection system (FuMB-Gerät) especially developped for the S-boats was FuMB 32 "Flores", 0perating in teh frequency band 110 - 300 MHz. It could determine the bearing of an emission and was mounted onto a turnable mast. -The FuMB 32 had a width of about 50 cm and utilized the "Samos"-receiver.
The FuMB 24 "Cuba 1a" aoperated on wavelength 9 cm and provided an exact bearing of the detected emission at big distance. Its compact antenna was ideal for the employment on S-boats.
In many cases "Flores"- and "Cuba 1a"-antennas were mounted to a comman mast which stood directly behind the bridge. The mast could be turned by the operator using a handweel.
The "Naxos"-receiving systems FuMB 23 and FuMB 28 came into use on S-boats mid 1944. They employed a modern turning antenna (ZA 290M) under a plexiglas dome. The system detected at long range the emissions at 9cm wavelength of aircraft and surface units.
A further radar detection system (FuMB-Gerät) that was employed on S-boats was FuMB 26 "Tunis". It was mainly employed on the boats of classes "S 30 and "S 151" in the Mediterranean.
But towards the end of war also on other units further radra detection systems (FuMB-Geräte) were tested thereamong the antenna "Libyen" operating in the range 2 - 20 cm and teh miniature FuMB 33 "Lilliput", built for hand use and operating at 9cm wavelength. FuMB 33 had mainly been developped for employment on LS-boats.
All pictures from Krakow "Schnellboot in Action"