Propulsion and Speeds  
   
          Speed is rarely noted in U-boat KTBs.  Rather, U-boat COs referred to the setting and configuration of the engines.  Unless otherwise noted, it may be assumed that both engines were running together.  Most often the CO would enter the abbreviation for the telegraph setting.  The table below gives the propeller revolutions per minute and resulting speeds for Type VII and Type IX U-boats for various telegraph settings.  
   
 
 
Surfaced
Type VII
Type IX
German Abbreviation English R.P.M. Speed R.P.M. Speed
Kleine Fahrt K.F. dead slow 161 6.1* 160 7
Langsame Fahrt L.F. slow 263 9.63 240 11
Halbe Fahrt H.F. half speed 310 10.98 300 15
2x H.F. 3/5 speed 404 14.24 400 17.5
Grosse Fahrt G.F. 3/4 speed 469 16.73 460 19
2x G.F. 4/5 full speed
Äusserste Kraft A.K. emergency speed 485 17.29 480 20
Dreimal A.K. 3x A.K. utmost speed
*Speeds on two engines in calm water
For a short burst of high speed on surface, if the state of the batteries permitted, speed could be increased about half a knot by running the electric motors and Diesels simultaneously. 
U-boats sometimes used "Diesel-Electric" (dieselelektrisch) propulsion, running only one Diesel; it drives its own shaft and motor which, acting as a generator, supplies power to the motor on the other shaft.  The electrically-driven shaft makes about half the revolutions of the Diesel-driven shaft.  Economical Diesel-electric speed is about 6 knots.  It has the advantage that the idle engine can be serviced, and that the operating Diesel engine can run at its most efficient speed. 
       
     
Submerged
     
Type VII
Type IX
Kleine Fahrt K.F. dead slow 60 1.5 60  
Langsame Fahrt L.F. slow 90 3.0 90  
Halbe Fahrt H.F. half speed 160 4.1 110  
  2x H.F. 3/5 speed 200 5.23 160  
Grosse Fahrt G.F. 3/4 full speed 233 6.1 180  
Äusserste Kraft A.K. emergency speed 280 7.4 210  
 
  *R.P.M. and Speeds above are from the British Cumulative Edition (CB 04051 103)  Those for the type VII were observed during testing of U-570.  
  Great stress is laid on finding the most silent running speed for each U-boat.  It is generally  about 90 r.p.m. and this "silent" speed is known as "Schleichfahrt".   
     
  Propulsion Vocabulary  
 
Abgas Exhaust gas
Abgasgebluse Exhaust gas driven compressor
Abgasklappe Exhaust gas valve
Abgasschalldämpfer Muffler
Abgeschaltet Disconnected, off, shorted
Abnahmeprobefahrt Full power trial, acceptance test run
Abschallklappen Diesel exhaust valves
Abscheider Separator
Akku Battery accumulator
Akkumulator (Akku.) Battery
Akkumulatorenbatterien Storage batteries
Akkumulatorenraum (Akkuraum) Battery compartment, accumulator room
Amperemeter Umschalter Amp meter selector switch
Amperestunden (Ah.) Ampere hours
Anfahrgetreibeölpumpe Oil pump for starting gear
Angelüftet Operated by hand
Ankerschluss Armature circuit
Anlassen To start up
Anlasser Starter
Anlassflaschen Starting air bottles
Anlassluftleitung Air starting circuit
Anlaßschütz Accelerating contactor, speed controler, start switch
Anlaßventile Starting vlaves
Anlassvorrichtung Starting mechanism
Antreiben To propel
Antrieb Propulsion
Antriebsgestange Propulsion shaft
Antriebskraft Driving force
Antriebsmaschine Driving engine
Antriebswelle Drive shaft
Anwerfen Start (engine)
Anzeiger Annunciator
Armaturenbrett Instrument panel

Aufgeladen

Charged
Aufladegruppe Supercharger group
Aufladen der elektrischen Batterien Charging (of batteries)
Aufladenmarsch Charging battreries as the boat transits
Aus Off
Ausblasekästen Exhaust cases, manifolds
Ausdauer Endurance
Auspuff Exhaust
Auspuffqualm Exhaust smoke
Auspuffsammeltöpfe Exhaust manifold
Auspufftöpfe Silencers, mufflers
Äusserste Kraft (A.K.) Emergency speed
Batterie meßtafel Battery measuring panel
Batteriehaupschalter Main battery switch

Batterien in Reihen geschaltet

Battery connected in series
Batterien aufladen To charge batteries
Batterien parallel geschaltet Batteries connected in parallel
Batterieparallelserienschalter Battery parallel series switch
Batterieselbstschalter Battery automatic switch
Belüftung (Akkuraum) Ventilation (battery compartment)
Betrieb Operation, Plant
Bordschweißanlage On board welding system
Bremse Brake
Brennkammer Combustion chamber
Brennstoffausnutzung Fuel utilization
Brennstoffersparnie Fuel saving
Brennstoffübernahme Fuel comsumption/Fuel taken over
Brenstoffmangel Fuel shortage
Bürstensorte

Brush (electrical)

Chlorgasvergiftung Chlorine gas poisoning
Dauerbeanspruchung Endurance stress
Diesel motor (DM) Diesel engine
Dieselantrieb Diesel engine propulsion
Dieselelektrisch Diesel-electric propulsion
Dieselmotorenraum Diesel engine room
Dieselöl Diesel oil
Drehschalter Rotary switch
Drehzahl Number of revolutions, RPM.
Dreimal A.K. (3 x A.K.) Utmost speed
Driestoffpumpe "3 fuels" pump (for a Walter propulsion system)
Drosselklappe Wing type throttle valve
Drosselscheibe Throttle gate
Druckknopf Push button
Drucklager Thrust bearing
Druckölanlage Pressurized oil system
Druckölflaschen Pressure oil accumulator flasks
Druckölsammelbehälter Pressure oil collecting tank
Druckschalter Pressure controls (for hydraulic system)
Druckventil Check valve
Durchspülen Flushing (of hoses, lines and tanks) - after a MB and RFO tank was emptied of fuel, it was flushed to prevent leaving an oil trace
Ein On
Einkuppeln Engage (as for clutch)
Einschleifvorrichtung Grinding mechanism
Einspritz Injection
Einspritzflaschen Injection bottles
Elektrizitätsmaschine Electric supply generator
Elektroherd Electric source
Elektro-Maschine (EM) Electric motor
E-Maschine (EM) Electric motor
E-Maschinenraum/E-Raum Electric motor compartment (contained electric motors and main switchboards)
Entlüftung Exhaust
Entluftungsventil Exhaust Valve
Ersatz Reserve
Erschöpfte Batterie Run-down battery
E-Zusatz E-additive (using E-motors to supplement Diesels)
Fahrbühne Control platform
Fahrschalter Hand-ooperated valve (for hydralic system)
Fahrstand Control position
Fahrstufe Drive position (engine telegraph setting)
Fahrstufen Driving increments
Fahrtrichtungsschalter Drive direction switch (ahead-astern)
Fahrtsteller Speed controller, Astern actuator
Fahrtstufe Operating combinations, as in alternating propulsion
Feder Spring
Federkupplung Spring clutch (connectes each diesel engine to the shaft)
Fehlenzeige Indicated loss, deficiency
Fernschalter Remote switch
Fiberdichtungen Fiber washer
Flurplatten Floor plates - as in the Diesel or E-motor rooms
Förder Extraction
Forderanschluss Intake connection
Funkenfänger Spark arrestor
Funkenlöscher Spark extinguisher
Gasförming Gaseous
Gasöl Diesel fuel
Gebläse Supercharger, blower, fan (M.A.N.diesel engine supercharger)
Gebläsestutzen Blower nozzle
Gegensteuern Set rudder to balance one cut-out propeller
Gegriffen Clutch
Getriebe Gearing
Getrieböl Reduction gear oil
Gewindekupplung Threaded coupling
Gleichstrom

Direct current

Grosse Fahrt (G.F.) 3/4 speed
Grundlager Foundation bearings
Gummidichtung

Rubber seal, gasket

Hähne Stop cock
Halbe Fahrt  (H.F.) Half speed
Halslager Journal bearing
Haltefedern Retaining spring
Handpumpe Hand pump
Hauptschalttafel Main switchboard
Hauptschalttafeln Main switch table
Hauptwellenachse Main shaft axle
Heizer Stoker
Heizkörper Radiator
Heizöl Fuel oil
Herausziehen

To extract

Hervorrufen To generate
Hilfsschalttafel Auxiliary switch panel
Hintereinander geschaltet Connected in serial (as in connecting batteries)
Hochbehälter Reservoir
Höchstfahrt Best speed
Höchstgeschwindigkeit Maximum speed
Höchstleistung Maximum power
Hubzahl Engine indicator
Hubzylinder Lifting cylinder (as for periscopes)
Impulsgeber Instigator
Innenbunker Internal tank
Isolierband Friction band
Kalk Lime
Kalkmilch Lime solution
Kammer Chamber
Kapazitätsprobe Battery capacity test
Kegel Pin, plug (valves)
Kegelrad Bevel gear
Keilriemantrieb Wedge-shaped driving-belt
Kettenrad Sprocket wheel
Klauenkupplung Jaw/claw coupling
Kleine Fahrt (K.F.) Dead slow
Kolben Piston
Kolbenring

Piston ring

Kolbenstange

Rod

Kolbenventil

Valve

Kollektor Commutator, collector ring (electrical)
Kommandoelemente Controls
Kontaktgeber Electrical contact transmitter
Körper Body, casing
Kraft Force, power
Kraftstoff Fuel
Kraftstoffhochbehalter Gravity fuel container
Kraftwerk Powerplant
Kugellager Ball bearing
Kühler für Haupt E-Motoren Cooler(s) for main electric motors
Kühlwasser Cooling water
Kühlwasserdruck Coolant pressure
Kupplung Clutch
Kurbel Crank
Kurbellager Crank bearing
Kurbelwannen Crank case
Kurbelwelle Crank shaft
Ladeanschluß Charging connection
Ladezeit Charging time
Ladezustand State of charge
Ladung Charge (electrical), Cargo
Lageaustausch Position for transfer/exchange
Lager Bearing
Landanschluss Shore connection (electrical)
Langsame Fahrt (L.F.) Slow
Längsseitegegangen Went alongside (for refueling, etc.)
Laufbuchse Liner as in cylinder liner
Lauge Lye
Leerblasens Blowing empty (of hoses and lines)
Leistungsangaben Performance figures
Luftentöler De-oiler (for hydraulic system)
Mannloch Manhole
Marschfahrt (M.F.) Cruising speed - most economical speed
Maschinenfabrik (M.A.N.) Diesel engine manufacturer
Maschinenraum Engine room
Maschinenschaden Engine trouble
Maschinenselbstschalter Motor circuit breaker
Maschinenstand Engine control platform
Maschinentelegraf Engine telegraph
Maschinist Engine room artificer
Mechaniker Engineman
Mehrankerumformer Multi-armature converter (DC-AC)
Meldelampe Indicator lamp
Messfahrt A drive test for calibrating fuel/current usage
Montageluck Installation hatch (battery)
Motor Motor, engine
Motorenölkühlraume Lube oil cooling evacuator
Neben Shunt
Nebenschaltafel Shunt switchboard, switch panel
Nebenschlussmotor Shunt wound motor
Nebenschlusswicklung

Shunt motor winding

Nocken Cam
Nockengetriebe Cam gear
Nockenwannen Cam shaft case, cam shaft mounting
Öl Oil
Ölabstreifring Oil wiper rings
Oldicht Oil tight
Ölfestem Oil insoluble
Ölmotor Oil engine
Ölwassergemisch Oil water compound
Parallel Parallel (E motors or batteries)
Parallel geschaltet Connected in parallel (as in connecting batteries)
Petroleumbunker Paraffin bunker
Petroleum-Motor (PM) Paraffin engine
Pferdestärke (PSe, P.S.) A unit of power measurement used in Germany from the end of the 19th century until recently - closely equivalent to horsepower - 1 pferdestärke = 0.9863201 horsepower
Pleuelstange Connecting rod
Rechenstelle Control point
Regler Regulator
Reibungskupplung Friction clutch
Reichweite Range (Überwasserfahrt = surfaced) (Unterwasserfahrt = submerged)
Reinigung Cleansing, purifying
Reisemarsch Cruising speed
Reserve Reserve, spare
Reservebehälter Reserve tank
Ringstopfbuchsen Ring stuffing box
Sammelleitung Bus, mainfold
Sammeltank Collecting tank
Säureabfall Acid loss
Schacht Shaft
Schalldämpfer Muffler
Schalter Switch (Sch.)
Schaltschema Schematic
Schalttafel Switchboard
Schaltvorgang Circuit switching
Schlauchleitungen Hose lines
Schlauchverbindung Hose connection (for refueling)
Schleichfahrt Silent running speed
Schleichmotor Creep motor
Schlepperverbindung Towing connection
Schleuse Sluice, lock
Schmieröl Lubricating oil
Schmieröltank Lubricating oil tank
Schmierölverbauschstank Lubricating oil consumption tank
Schmierung Lubrication
Schmutzöl Waste, used oil
Schneckenantrieb Worm-drive
Schnorchel Snorkel
Schnorchelfahrt Snorkeling/snorkel traverse
Schnüffelventil Bleed valve/poppet valve
Schraubenschutz Propeller protection
Schwanzwelle Tail shaft - propeller shaft between the motor and the propeller
Schwebeteilchen Suspended particles
Schwimmerventil Float valve - as for the snorkel
Schwingungsdämpfern Vibration dampers
Seebeölung Refueling at sea
Seebestattung Burial at Sea
Serie Series (E motors or batteries)
Sicherheitssieb Strainer
Sicherungsautomat Circuit breaker
Spaltfilter Oil filter
Spannung Voltage
Spannungsmesser Voltage meter
Spannungsregler Voltage regulator
Spannungsschutz Voltage safeguard
Sparsamer marschfahrt Ecconomical cruise speed
Sparsauste Fahrt Most economical speed
Speisung Power supply
Spezifisches Gewicht (S., S.G.) Specific gravity -  ratio of the mass of a material to the mass of an equal volume of water at 4 oC. - as for the battery acid
Stell Servo
Steuerfähigkeit Steerageway
Steuerschieber Control valve (for hydralic system)
Steuerstand Control platform
Stopfbuchse Piston-rod collar
Störungsexerzieren Damage control exercises
Stoss End, thrust
Strom Current (electric)
Stromaufnahme Electric current consumption
Stromerzeuger Electric generator, dynamo
Stromstärke Amperage
Stromverbraucher Powerload
Stromverteilung Power distribution
Stromwächter Current relay
Stutzen Nozzle
Tiefentladung Deep discharge of the batteries – in preparation for servicing
Treibölbunker Fuel-oil bunker
Treibölverbrauch Fuel oil consumption
Treibölverbrauschsbunker Fuel-oil consumption bunker
Treibstoff-Bunker (Motor) fuel bunker
Trennschalter Circuit breaker, cut-off switch
Triebwerkswelle Drive shaft
T-stoff Abbr. for Hydrogen peroxide
Turbinenläufer Turbine rotor
Turbogeblase Turbo blower
Überhitzung Overheating
Überladung Battery over-voltage – charge voltage equalization of all battery cells
Ubernahmepumpe Loading pump
Übernommen Taken over (fuel/provisions etc.)
Übertragungsgestange Operating shaft
Übertragungszahnrad Transmission gear
Umdrehungen pro Minute (U/min., Umdr.) Revolutions per minute
Umformer (Umf.) Transformer or Converter (DC-AC)
Umschalten To change over
Umstellen To switch to, shift, or convert
Umsteuervorrichtung Reversing equipment/installation
Unterwassermeilenfahrt Submerged mile - measurement made of speed at various RPM settings during UAK-trials
Ventiltellerbruch Valve disc/head broken
Verdampher Vaporizer
Verflüssiger Liquefier
Vergaser Carburetor
Vierstoffreger "4-fuels" regulator
Vollastfahrt Full speed test run
Volle Kraft Full speed
Wellen Shafts
Wellenbremse Shaft brake
Wellengetriebe Shaft, gearing
Wellenhosen Bossings (curved portion of ship`s shell plating that surrounds and supports propeller shaft)
Wellenumdrehungsanzeiger

Shaft rotation (rpm) indicator

Wrasen Vapor
Zelle(n) Cell(s) (of batteries)
Zeuger

Generator, dynamo

Zurück Astern
Zweimal Grosse Fahrt (2 x G.F.) 4/5 full speed
Zweimal Halbe Fahrt (2 x H.F.) 3/5 speed
Zwischenwelle Main drive shaft
Zylinder Cylinder
Zylinderdeckel Cylinder cover
Zylinderkopf Cylinder heads
 
     
     

 


 

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