ISBN 0-85420-945X
viii + 116 pages

Introduction; Foreword; tables; diagrams; Index

Appendices: Lt Colvin's Report; Report by Commanding Officer, HMS Hecla

   Unfortunately for the Royal Navy, when U-570 was captured in August 1941 off Iceland, no one in the Admiralty had a copy of Eberhard Rossler's informative book, The U-Boat: The Evolution and Technical History of German Submarines. That oversight on the part of the RN can be forgiven since Rossler's book wasn't published for another forty years. Still, a copy of Rossler might have saved the Brits the time and effort they devoted to studying and testing their prize.
   Soon after capturing U-570, the RN managed to get it safely to the UK where it was repaired and rechristened HMS Graph, serving on active duty with the Royal Navy after extensive trials. Information gathered during refitting and sea trials provides the bulk of the book. Although part of the first chapter gives a brief outline of the history of U-570 and its capture, that comprises only a small fraction of what is really an extended technical report about the boat's inner workings.
   The following main topics are covered in individual chapters:

Electrics
Torpedo Armament and Equipment
Gunnery
W/T and A/S Equipment
Compasses, Periscopes, Binoculars, Miscellaneous Machines and Fittings
Construction and Main Engines

   Here's an example of the kind of data contained:

Operation of the Main Engines

Starting air is stored in two bottles of 200 litres capacity, one behind each other; the bottles are charged through a reducing valve from the main line to a pressure of 30 atms.

Interlocks

(i) The engine cannot be started with the blower clutched in.
(ii) The reversing lever cannot be moved unless the fuel lever is at stop.
(iii)The starting lever cannot be moved unless the reversing lever is at Ahead or Astern.
(iv) The fuel lever cannot be moved to a position above that required to give a speed of about 420 r.p.m. until the blower is clutched in.

2 The induction trunk normally takes its air through two ports which are automatically shut when the blower clutch is engaged.

3. Air for the engine is normally brought to it through an outboard induction pipe with its inlets at the highest part of the bridge screen, approximately 4 ft. 6 in. above the conning tower hatch. The two leads are married into a valve just above the hull and abaft the conning tower trunk This valve is operated from the control room. The hull valve is between the engines and near the starting platform. The inboard lengths of the trunk are taken round the hull and down to approximately the level of the crankshaft.

4. Lubricating oil is stored in two reserve tanks of 3,250 litres capacity each. Between these are the drain tanks, one to each engine, and each hold 800 litres.

5. The engine-driven lube-oil pumps, which are of the gear type with automatic change-over valves for astern running, take their suction from these tanks. The engine bearing pressure is 1 atm. The maximum capacity of each pump is 380 litres/min. (23m./hour) (5,000 galls./hr.). A cooler and filter are provided in the lubricating system of each engine, the coolers being fitted with bye-passes for temperature control. The strainers are of the Auto-Klean type.

6. There is also a lube-oil purifier which takes its suction from each drain tank and the dirty lube-oil tank. It has a water-washed bowl, the water being normally taken from the engine circulating system and then passed through an electrical heater. There are two gear pumps incorporated with the separator, one pumping clean oil from and the other dirty lube, oil to the machine. The capacity is 300 litres/hour (66.2 galls./hour).

7. Circulating water is taken through double sea inlets, one each side of the starting platform, by engine-driven pumps of the bucket type, one to each engine The maximum capacity of each pair of pumps is 400 litres/min. (57.2/hour) (5,300 galls./hour).

8. The circulating water is led through coolers and to the bottoms of the liners. The discharge is led to the group exhaust and muffler valves and tanks, and thence to an expansion tank at the after end of the conning tower casing which forms the compensating water supply to the external oil fuel groups. Fuel oil is compensated into two overhead gravity tanks each of capacity of 400 litres, passing through a filter in the process. From the gravity tanks it passes through a flow meter which can be bye-passed, and then to the fuel boost pump, which can also be bye-passed. The oil then passes through an Auto-Klean type filter and so to the fuel pumps.

   As can be seen, this actually goes far beyond the level of detail contained in Rossler's book. However, readers must bear in mind that the British report is based on their investigation and understanding of a captured boat. Although there is a one-page Introduction (by Jak Mallmann Showell) and a one-page Foreword (by Terry Andrews), there are otherwise no notations by the editor regarding the accuracy of any of the information contained in the wartime reports. That's not to say any of the data is wrong, or even suspect, but there's simply no indication that anyone has gone back and checked the British data against the original German specifications.
   Following eighty pages of technical reports, the book adds two appendices: one by the RN officer who took temporary command of U-570 to get it sufficiently shipshape for towing off the beach in Iceland, and one by the CO of HMS Hecla who subsequently took charge for preparing the submarine to sail under its own power to the UK. The book concludes with about twelve pages detailing exercises conducted with Graph to help improve Allied anti-submarine warfare tactics. These exercises provide some of the most interesting parts of the book, including limits of underwater endurance. For example, the exercises indicate the following:

• Maximum underwater range: 63-70 miles
• Maximum time underwater (in motion): approximately 50 hours
• Maximum time underwater (resting on the bottom): less than 60 hours

   With a full understanding of all the physical performance characteristics, (such as minimum worthwhile surfacing time, optimum surfacing time, and "miles per surfaced hour"), the last part of the section on trials includes descriptions of "dry exercises" explaining different tactics for U-boats attempting to escape underwater after being spotted by an aircraft.
   As it stands, many readers with an interest in U-boats will find this volume (and all the other volumes of the U-Boat Archive series) fascinating. While it can certainly stand on its own as a wartime document worth studying simply to become familiar with the level of Allied knowledge about U-boats, in some respects the book could have been improved by careful annotating to evaluate what the reports got right and what (if anything) they got wrong. In any event, we applaud the Military Press for reprinting important historical documents of this nature.
   Available from online booksellers, local bookshops, or directly from the Military Press.
   Thanks to Military Press for providing this review copy.