Schnellboot Signals Schnellboot Archive


Signals are an important element of seafaring and naval warfare. Ships must communicate with each other and Captains must communicate with their superiors ashore. For the S-Boats, which often operated at night in formations, communication was especially vital to navigation, formation keeping, target location and attack coordination. Signalling methods utilized by the S-boats ranged from the ancient practice of flags, semaphores and lanterns to the most modern radio and radar technologies of that era.

A Reciever/Transmitter type FuG/V aU provided ship to shore communication, as well as general reception and long range communication. It was mounted in the radio room forward and below the wheelhouse. This was the same type used in larger Luftwaffe seaplanes This provided a simple means for air/sea cooperation. In actual practice this was often hindered by the Luftwaffe High Command's lack of interest in maritime operations and the general scarcity of resources.

A radioman stood by the helmsman as part of the bridge crew. He operated the short range VHF type Lo 1 UK 35 voice transmitter reciver in the wheelhouse, which enabled rapid communications from ship to ship. However, when conditions allowed, communication between ships was undertaken by signal lamp or flag semaphore. The earlier S-Boats had mechanical semaphores in the mast for signalling. Although antiquated, the chief advantage of visual signals is their short range; they cannot be intercepted by an enemy over the horizon.

Some later S-Boats were equipped with radar and radar countermeasures. The FuMo 71 "Lichtenstein B/C" was a fixed radar array that could scan a 35 degree arc ahead of the boat. Its range was very limited, about 2km for a destroyer, 3km for a larger merchant ship, but it was extremely accurate for ranging, and useful in fog. It was adapted from Luftwaffe equipment considered obsolete, and went into limited Kriegsmarine service in late 1943.

After an initial lead in radar development, Germany began to lag behind the Allies. Recognizing this, the ever resourceful German engineers developed a number of somewhat effective radar counter measures including passive radar detection and ranging. Some of this technology was miniaturized and adapted for use on S-Boats beginning in March 1944. The apparatus enabled the S-Boat to see without being seen: when properly used, it could locate and identify enemy forces based on their radar emissions while still beyond the useful range of the enemy's radar.

The FuMB Ant 3, code named "Bali 1", antenna (right) was widely used on the armored bridge boats. It was only approximately 25cm wide. The "Bali 1" antenna was part of the FuMB 29 "Bali-Anlage" radar surveillance system. It could be used with a FuMB 4 "Samos" Reciever (90-470 MHz), a FuMB 9 frequency indicator (146-264 MHz), or a FuMB 10 "Borkum" signal detector (100-400 MHz). The signals were fed through a booster to an FuMZ 1 Oscillograph, where they could be viewed and interpreted by the operator. This system was often used in conjuction with other FuMB radar detectors, mounted on short masts directly behind the bridge cockpit. Miniature portable detection equipment for E-boats was in the experimental stages at the end of the war.

Further experimentation attempted to conceal the boats to enemy radar. These "radar camouflage" experiments were the roots of modern "stealth" technology. Various materials were evaluated for their ability to either absorb or scatter radar refection. A reflection dimming rubberized coating known as "Tarnmatte" was developed and used on U-Boats. Tests to conceal S-boats to enemy radar using measures such as "Tarnmatte" were partially successful at certain wavelengths, but apparently did not develop to operational use.

Radio operators were among the most highly trained specialists in the Kriegsmarine. As electronics became increasingly more integral to the technology of war, radiomen operated and maintained a variety of cutting edge equipment incuding radar, sonar and accoustical detectors. Intensive training ranged from fluency in morse code and cryptography to the repair of complex electronics. A skilled radio operator was part of a ship's combat capability. He could use his reciever to locate enemy ships based on their signal strength or use his transmitter to jam their signals. In recognition of the nature of their work which required a dexterous hand, radiomen were generally excused from heavy physical labor aboard.

Manouvering a Schnellboot in combat conditions required precision navigation and steering under the most trying of conditions.On a typical combat sortee, the commander, helmsman and navigator worked together to guide the vessel through fjords, narrow inland seas or rock studded coastal waters in pitch darkness. This dangerous feat of seamanship demanded great skill, concentration and constant vigilance.

The S-Boat's few navigational tools were laid out in a simple and logical manner. The navigator plotted the course on a tiny table in the rear of the wheelhouse. Several compasses were carried onboard; a central compass was mounted amidships in a binnacle. The captain, navigator and helmsman had smaller compasses mounted in their respective positions.

A Radio Direction Finder (RDF) was standard equipment. Although not always mounted, its distinctive loop antenna fit into a socket at the rear of the wheelhouse. The RDF was used to pinpoint the boat's precise position by triangulating radio transmissions from known positions ashore. The RDF antenna could also be used to locate the position from which an enemy ship was transmitting.

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Sextant and rangefinder in use on this mid-war boat.

Original Kriegsmarine Sextant made by Plath, 1942.

The navigator in his tiny charthouse aft of the wheelhouse.

The Radio Operator's cabin.

The table doubled as the Radioman's bed.

FuG V transmitter.

FuG V reciever.

Inside the wheelhouse, matte black bulkheads eliminated reflections. The radioman operates the ship to ship R/T.

Lo 1 UK 35 ship-to-ship R/T unit. Shown here in its transportation case.

Note the Fu Mo 71 antenna and mast fitted to this mid-war boat.

The FuG set as mounted in a Do18 flying boat.

The time-honored method of ship to ship communication. (from Kemnade Die Afrika Flotille.)

Pennants for two recent victories.

Compass sight. This device provided a magnified view of the object in the crosshairs, with a split view that also showed the precise bearing. There was an internal flip-down orange sun filter and night illumination of the compass.

Compass instrument with sight.