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The Technology

            While end of war comparisons clearly showed the Japanese torpedoes were superior and German U-boats had superior speed, sonar, optics, engines, and batteries and could dive quicker and deeper, overall American submarines won in part because of the technological edges[1].  Uniquely, Americans made their submarines with better habitability.[2]  American submarines started the war with radar, TDCs, and air conditioning[3].  As the war went along, VADM Lockwood ensured as soon as new or improved technology came out, the submarines, which ever command, got them on the very next return from patrol[4].  VADM Lockwood took each loss very personally, especially the loss of CDR Morton and Wahoo, and this drove his desire to improve the chances of successful patrols and safe returns.  It was said Lockwood would do anything for “his boys.”[5]

Some of the technology introduced during the war included HF/DF, VHF radios, TBT systems, noisemaker decoys, night periscopes with ST radar antennae built in, and FM sonar for mine detection.[6]  Of great importance operationally, but not necessarily out on station, were the Magic code decryptions.[7]  Finally, just before war’s end, high speed snorkels were introduced.[8]  Yet, in the end, the technological edge needed came down to basics, engines and hulls.  Without good engines and strong hulls, all the rest would be throw away at best.

            The original Holland submarines were powered by gasoline engines on the surface and electric motors running off batteries when submerged.  The 1910s brought a switch to diesel engines to get rid of the gasoline fumes and reduce fire hazard.  The years following World War I brought development in diesels and recognition in the superiority of German diesels in particular.  Reliance on foreign engines, though not desired, seemed inevitable.

            After inspection of the captured U-boats, the obvious. engine solution quickly became M.A.N. diesels.  In the U-boats, these engines had proven fuel efficient and reliable, giving the small German craft enough power.  With the postwar scale up in American submarine size, the Navy had M.A.N. built larger engines for the boats.  With the drive system of the day, Holland’s direct drive, a two screw submarine needed two engines.  An extremely large (such as the V-class) boat needed two extremely large engines.  The M.A.N. engines did not scale up well.

            The first apparent solution to relying on a foreign built engine was to get it license built here.  A not unheard of option in the international military-industrial complex.  France had used a Krupp designed fuse for its artillery shells manufactured in France under license.  For that matter, most warring nations in the Great War used a licensed copy of the German K98 Mouser as infantry rifles (particularly the British .303 Enfield and American 1903 Springfield rifles).  So why not have some one in America build German diesels.

            With assistance from the Navy, an Ohio company, H.O.R. (Hooven-Owens-Rentscher) gained license to build M.A.N. designed engines for the U.S. Navy[9].   Approximately one third of the submarines that began going to war in 1941 and 1942 were equipped with H.O.R. engines[10].

In the years leading to the mid 1930s, diesel powered submarines (and their gasoline powered predecessors) were considered direct drive.  Direct drives had the engine connected directly to the propeller shaft.  This physically limited the boat to one or two engines as it had one or two propellers.  Since the number of propeller shafts on a submarine was limited, to get more power required a larger engine.  Larger engines required more space.  More space required a larger submarine, which needed more power, and so on. 

The direct drive system connected the diesel engine to the shaft with a motor-generator via clutches on each side.  To operate on battery, the diesel clutch was disengaged and the batteries powered the motor-generator.  As no gear train existed, direct drive boats were                         Figure  SEQ Figure \* ARABIC 28 Direct Drive Power Train

required to shift to electric power to back the boat[11].  (No gears, no reverse gear).

Beginning with the Cachalot class, these designs had been pushed far enough.  The next development needed was a better engine system.  The solution the Navy went with – diesel-electric drive.  Diesel-electric drive differs from direct drive in a fairly simple manner.  The diesel engine is directly running a generator.  Each engine runs its own generator.  The output of this generator goes to the electrical load controls[12].  This can be used to run the electric motors on the propeller shaft, or used to charge batteries, or split to do some of each.  In this fashion, four engines could drive two motors for a higher top speed with smaller overall engines.  With this arrangement, a gear train could be built in or left off at the designer’s desire[13].

            Along with the needed changes in drive type, improved engines were needed.  The        

          Figure  SEQ Figure \* ARABIC 29 Diesel Electric Drive Power Train                     reliance on M.A.N. designed engines not only bottlenecked the U.S. Navy into using a foreign engine, but the M.A.N. engines were not working out.  To assist in the development of reliable diesel-electric systems, the Navy put forth a grant of $10,000 (in   1930s money) for the development of high performance systems.  Knowing this diesel electric system had other uses beside driving submarines (the modern diesel-electric railroad engine) meant the Navy did not have to foot the entire bill for development and could benefit from developments from other sources[14].

            Along with H.O.R., the development grant brought in two new engine providers.  General-Motors-Cleveland built a Winton designed diesel that proved to great reliability.  A 400 V-16, its medium size to power made this a welcome engine for the machinist mates.  The alternative was the 9 or 10 cylinder Fairbanks-Morse.  This engine used opposing pistons to gain more power per stroke[15].  The piston faces were cupped so when the pistons touched, the cups formed the combustion chamber.  This arrangement, while complex, proved to give more power in less size than the other engines[16].  Both new engines proved a hit with the railroads as power plants for the diesel-electric prime movers.

            As the war began and H.O.R. engines boats hit the water, problems quickly arose.  In shake down trials, the H.O.R. engines proved over and over to be unreliable.  The failures were multiple.  Gear teeth broke, crankshafts vibrated, engines just broke.  Upon hearing the Navy’s              Figure 30 Fairbanks-

report, H.O.R.’s chief engineer collapsed and died from      Morse Piston Arrangement

a stroke.  H.O.R. and the Navy brought in Robert Ramsey as a troubleshooter.  He worked with M.I.T. metallurgist Frank Lewis.  The results of their investigation showed the steel was chemically perfect but the entire batch had cooled too fast.  This made the crystalline structure of the steel wrong for the strength needed.  As this improper cooling occurred under H.O.R. control, the Navy refused to install any more H.O.R. engines.[17]

            The boats already equipped with H.O.R. engines retreated to shipyards.  There, ship fitters feverishly overhauled the engines manufacturing any parts possible.  The H.O.R. boats would go to war like that.  Due to their unreliability and odd parts requirement, the “powers that be” decided to keep all the H.O.R. equipped Gato class boat together.  They were stationed in Brisbane on Australia’s east coast.  The combined problems of these engines kept Brisbane operations limited while they were there.  By late 1942, COMSUBPAC Operations drew the line on the H.O.R. engines[18].  VADM Lockwood scheduled space at Mare Island, CA for all 12 H.O.R. boats and removed them from fleet service till such time as reliable GM-Wintons or Fairbanks-Morses could be installed.  Needless to say, this engine severely affected the ability to wage war against Japan.  The first repaired H.O.R. boats returned to service November 1943, Gunnel under command of John S. McCain Jr.[19].  As stated before, CDR Voge, in charge of issuing movement orders based on Magic intercepts had more Magic generated tasking than he had submarines to use it till the H.O.R. boats were back in the green[20].  By early 1944, the return of the H.O.R. boats raised RADM Christie’s forces to 30 fleet type submarines[21].

            With the quality of the engines difficulties, came other construction quality worries.  But with only one exception, the shipyard, Navy and private, turned out high quality hulls.  Crampton ship yard in Boston, built a few hulls, of poor quality.  Of the few Crampton completed, the first to make it into combat failed to return.  On 2 December, 1944, Dragonet, a Crampton built boat, sank, then refloated, then inexplicably rolled 630 to port and stayed there.  She could only be towed to a Navy Yard for what turned out to be almost completer reconstruction.  In early 1944, several Crampton boats had trouble with fresh water tanks containing chemicals that had not been washed out following construction.  The poisoning of the crews on patrol rendered those boats ineffective till the tanks were steam cleaned[22].  Shortly there after, Portsmouth Navy Yard, the facility in charge of all submarine construction, closed Crampton down.  All hulls able to float were towed to other shipyards to be repaired and completed.  Portsmouth ordered the rest scrapped.[23]

            But Crampton was the exception.  The rule was best illustrated by Redfish.  Under command of LCDR McGregor, Redfish sank the IJN carrier Unoyu.  The escorts, loosing much face, retaliated to the extreme.  The resultant depth charging so damaged the boat, that VADM Lockwood ordered her back to Portsmouth Navy Yard were she had been built.  Met by yard workers upon return, the crew at first thought they were receiving a hero’s welcome.  As soon and the gangplank was down, the yard workers streamed aboard and moving the crew aside each examined the portion they had constructed.  They wanted to make sure they had not let anyone down and that their part of Redfish had held up.  This welcome did leave the crew moved[24].

            Other boats received poundings for their success.  Some were deemed so severe, they were taken completely out of service and retired during the war.  With 8 months left in the war, following 13 war patrols, Tautog became one of these.  Having sunk 26 JANAC confirmed ships, and bringing her crew back 13 times after severe trials, Tautog illustrates what would not have been done with a lesser quality boat.[25]

Figure  SEQ Figure \* ARABIC 31 Tautog's Battle Flag showing her record made possible by quality and pride.

Figure  SEQ Figure \* ARABIC 32 SD radar              Following quality to get the boats out on station, radar played the next biggest part in fighting the Japanese once on patrol.  The war found submarines equipped with SD radar sets.  Due to the fear of aircraft being so great in the interwar years, submarines were equipped with an aircraft warning set.  The SD radar gave now bearing, just range.  With a maximum range of 6 miles, and aircraft speeds up to or over 300mph, this set became a “dive detector[26]”.  If something showed on the scope holler “Dive, Dive, Dive!”[27]  SD radar stayed as an extra warning till replaced in 1944.[28]

Mid 1942 brought a more useful radar, the SJ.  The SJ radar   Figure 33 SJ radar was for surface search, i.e. target finding.  SJ radar was directional and had a range, depending on sea conditions and how far out of the water the submarine was trimmed, of 15 to 20 miles[29] (line of sight to the horizon from the height of the antenna).  By raising the antenna higher than a lookout could perch, radar saw past the horizon.[30]      

This radar displayed on a P.P.I. (Planned Position Indicator), the basic circular radar display.  The target showed as a blip on the scope and bearing and range could be calculated from there[31].  An extra advantage to SJ radar was its mast, which extended just like the periscope and could be extended while the submarine stayed submerged[32].  The SJ and P.P.I. gave the submarine commander “the big picture” conducting attacks.  For this reasons, commanders like LCDR Morton of Wahoo put their XOs on the periscope and watched the situation develop on the P.P.I. and TDC.[33]

The year 1944 brought two new radars.  SV replaced the early SD giving directional long range air search capability out to 30 miles or more.  To work with the SJ, as part of new night periscopes, a keyable ST radar antenna was built in.  This small directional antenna pointed where the periscope looked.  By using a simple morse code key, the Figure  SEQ Figure \* ARABIC 34 XO Dick O'Kane on Wahoo's periscope  radar operator could transmit a brief pulse and still remain undetected by the IJNs rudimentary radar detectors[34].  Throughout the war American radar proved vastly superior to Japanese radar or detection capabilities[35].  Once radar was actually fielded by Japan, Ned Beach reports being able to use that against the Japanese.  He reports of tracking a Japanese I-class submarine at night by the interference the Japanese radar caused on the American set.  By the time, the I boat got within its radar range, the solution was set and a torpedo was on the way.[36]  Similarly, Batfish sank three IJN submarines in three nights by using the same method.[37]

The TDC (Torpedo Data Computer) was a key piece of technology for the American effort.  Second only to the German U-boats version, this device was a electro-mechanical computer which took information from the ship’s gyro and Pitometer log (a rudimentary inertial navigation device) for the submarine’s information added visual information on the target’s bearing, estimated speed, estimated length, range, target’ course, and angle on the bow.  By updating the information over a fifteen to twenty minute period, the TDC worked down the errors in estimation to minimal levels and came up with a solution.  By using the solution, the submarine no longer needed to turn and point directly at the target.  Instead, the submarine could point as much as 900 off the track the torpedo needed to follow to intercept the target.[38]

By 1944, the change to night surface attacks brought another piece of equipment to assist the TDC.  This was the TBT (Torpedo Bearing Transmitted).  This was one or two binocular cradles mounted on the bridge with a grip with a trigger.  When the trigger was pressed, the bearing was electrically sent to the TDC.

The U.S. Navy’s cryptological section began serious. work on Japanese codes before World War I ended due to the foresight of many naval officers.  From their original work came the “Red” code[39].  The “Red” code was in part stolen from the Japanese consulate in New York to prepare for the Washington Naval Conference.  By the time the conference commenced, the Navy was reading the Japanese delegates instructions the same day the delegates did.  This knowledge let the Americans know just what the Japanese would concede and every bit of possible concession was take.[40]  By the eve of World War II, the Japanese diplomatic code in use (and broken) was the “Purple” code.  Unfortunately, not enough effort had been given Japanese Naval codes.  Attention focused on the “Admirals” code, but the rarity of use prevented enough information being gathered to generate a possible solution to the encryption[41].  Had more attention been focused on everyday codes, the merchant traffic codes and naval ship movement codes would have been broken earlier in the war.[42]

Early 1942 found the cryptological group in Hawaii, code named Hypo, reading portions of the Japanese Naval codes.  The product of this code breaking became known as “Magic.”  COMSUBPAC used this to sortie a major portion of the submarines in support of the Battle of Midway (see Figure 37).  Unfortunately, this obtained the typical results of using Magic to attack fast moving capital ships.  None were hit by U.S. submarines.

Magic gave information throughout the war on IJN ship movements, but of more importance in the end were the simple common “maru codes.”  These were the codes merchant shipping used to daily report position, course, speed, and destination back to Japan[43].  Between the simplicity of the code and the Japanese mania to have all this information available each day, CDR Voge in SUBPAC Operations busily plotted ships and submarines to sink them.  This maru code information eventually came under the general title of Magic information.  Late 1942 found CDR Rochfort out and Hypo renamed FRUPAC (Fleet Radio Unit, Pacific).  Recalled Coast Guard CAPT Anthony commanded the group generating the shipping information and worked through Jasper Holmes to keep Dick Voge in business.[44]

            Always a key to any group operation, communications played key parts in the success or failure of submarine operations.  VADM Hart in deploying his boats after notification of the Pearl Harbor raid, did so with the intention of notifying his submerged submarines of targets by using LF radio signals which could penetrate the water to a depth of about 100 feet[45].  Normal submarine communications were by HF radio.  Before the age of satellite communications, HF was THE long range radio communications method.  Unfortunately, HF communications were affected by weather, sun spots, the diurnal affects on the ionosphere, so frequent dead zones existed.  Also submarines running submerged could not receive or send HF signals.  By 1943, once pack operations had begun, the need for short range line of sight communications was desperately needed.  Methods such as passing messages in bottles between submarines running side by side were the result of lack of short range radios.  As 1944 began, the American control of the skies dictated submarines have a way to communicate effectively with patrol aircraft for safety’s sake as well as cooperative attacks.  The solution to this and the short range communications problems was the VHF radio.  This voice communications had short range to prevent interception or direction finding efforts and worked very well as the war progressed[46].

            Another part of the communication problem springing from wolf pack actions before VHF was solved by CAPT Momsen on the first wolf pack patrol.  Momsen developed a brevity code language to handle many situations with simple two letter codes[47].  As the war progress, the vocabulary of this brevity code grew.  If submarines were within visual range, hooded blinker lights could be used with this quite well.  Once the ST periscope radar came into common use, bright wolf pack commanders used this radar and the interference it made on other SJ scopes to use morse-code radar and communicate while submerged via Momsen’s code.[48]  This feature overcame many of the effects of Japanese air patrols, as one boat could be driven down and still signal contact to other boats in the pack.

            The major difference in American submarine technology that many other navies ranked as the most important was habitability.  The United States Navy built submarines with air conditioning for both the electronics (condensation killed more electronics than any other cause) and the crew (hull temperatures in the south Pacific could easily reach 1150.  Added to this were Kleinschmidt water distillers which kept the fresh water supply fresh, meant  fresh water storage could be smaller which allowed more fuel to be carried.  It also worked well enough that fleet boats even had fresh water showers[49].  While other submarine communities relied on salt water baths on deck if weather, operations, and the enemy permitted (which meant very few baths), American sailors in the tropics could shower with fresh water and defeat prickly heat and even severe illness.  The fleet submarines were built with large walk in freezers which allowed crews to eat a more balanced diet for longer into the patrol before canned goods took over the menu.  Again, the health benefits alone more than justified this.  The great choice of food kept submarine service morale higher than most of the military.  Probably most important, fleet boats had a complicated but useable toilet system when submerged.  German U-boat crewmen had to resort to using the bilges when submerged, which when added to the non-showered body odor, made life just that much more difficult.[50]

            The piece of technology VADM Lockwood credited with breaking Japan’s back was FM sonar.  This device, developed by J.N.A. Hawkins[51], was mounted on the bottom of the bow in such a way as to give an upward looking angle of 12 degrees[52].  The FM sonar, officially called QLA, was a short range set.  using frequencies above the audible range, small objects such as mines could be discerned.  This gave the sonar a short range measures in hundreds of yards instead of miles.  Introduced on Spadefish in July 1944, the early sets were reliable out to 600 yards[53].  By 1945, the reliable range was on the order of 750 yards.  The common name of FM sonar given by crews came from the electronic gong noise the set gave when it picked up a return.  Passage through a dense minefield made continual ringing the crews dubbed “Hell’s Bells.”[54]

            The advantage this short range sonar gave was to detect mines.  As Japan’s control of the seas collapsed and the submarines gained preeminence, Japan resorted to ASW minefields[55][56].  In quick order, experienced crew figured out FM sonar on the boat meant going into and through the mine filled straights protecting the Sea of Japan.  In the case of Tinosa, when she received QLA sonar, 35 men requested transfer off the boat for fear of striking a mine.  They were straight swapped with 35 men from the Shark.  In a strange quirk of fate, Tinosa easily passed through the minefields into and out of the Sea of Japan, while Shark was lost with all hands to a minefield near Tokyo Wan (bay)[57]. At first as FM sonar sets became available, VADM Lockwood had them installed in sets for wolf packs.  By April 1945, the collapse was gaining momentum to the point that “Uncle Charlie” send boats out singly as fast as the sets were installed.[58]  That month, his boats accounted for 28 ships totaling 54,784 tons.[59]

VADM Lockwood, ever protective of “his boys”, would not rest in pushing for any improvements that would bring more of his crews home.  In November 1943, COMSUBPAC created SORG (Submarine Operations Research Group).  Their mission was to analyze anything to do with operations and find the optimum way to do the task.  Using some of the first IBM Holerith machines, they bent folded, spindled, and mutilated any data CAPT Voge could give them from patrol reports.  SORGE evaluated the first wolf packs’ effectiveness and coordinated operations between submarines and patrol aircraft[60], compiled evidence to prove Mk XVIII malfunctions, and even mathematically calculated the optimum lookout binocular sweep pattern[61].

Other issues were worked on as they came up.  On 10 December 1943 for example, the Submarine Officer’s Conference met to address the immediate needs.  For 6 days, 30 experienced submarine officers (ranging from LT(jg) to VADM) hammered out the technical issues.  From this conference came noise maker decoys, the Mk XXVII anti-escort homing torpedo, radar absorbent (stealth) conning towers, and better sonic and supersonic sonar equipment.[62]  Sadly, in 1942 and 1943, the submarine design advantages and technological edges possessed by the United States Navy were easily canceled out by failures of the torpedoes and the failures of strategy and doctrine[63].

Figure  SEQ Figure \* ARABIC 35 IJN Cruiser on its way to the bottom

Figure  SEQ Figure \* ARABIC 36 How it got that way


[1] Padfield.  337.

[2] Ibid.  14.

[3] Ibid.  337.

[4] Beach.  35.

[5] Smith.  123.

[6] Blair. 762.

[7] Padfield.  477.

[8] Beach.  253.

[9] Blair. 1022.

[10] “Submarine Propulsion systems” ( 23 January 2005.

[11] Ibid.

[12] Blair.  44.

[13] “Submarine Propulsion systems” ( 23 January 2005.

[14] Blair.  40.

[15] An example Fairbanks-Morse diesel engine in operation can be see in the 1990s movie “Down Periscope”

[16] “Submarine Propulsion systems” ( 23 January 2005.

[17] Blair. 240.

[18] While command was not unified, use of Magic was controlled by COMSUBPAC and shared, and COMSUBPAC also scheduled the Pearl Harbor and Mare Island maintenance facilities for all submarines.

[19] He would be the second John S. McCain to obtain rank of ADM.  John S. McCain III left the family business at CAPT following a stay at the Hanoi Hilton and chose a different career. Ibid.  497.

[20] Ibid.  373.

[21] Ibid.  553.

[22] Ibid.  603.

[23] Ibid.  781.

[24] Ibid.  778.

[25] Ibid.  783.

[26] “Air & Sea Search Radar” ( 23 January 2005.

[27] Padfield.  337.

[28] “Air & Sea Search Radar” ( 23 January 2005.

[29] Padfield.  385.

[30] “Air & Sea Search Radar” ( 23 January 2005.

[31] The P.P.I. worked with a chart of matching scale so islands could be plotted for navigational fixes while submerged.

[32] Ibid.

[33] Padfield.  385.

[34] “Air & Sea Search Radar” ( 23 January 2005. Padfield.  387.

[35] Padfield.  385.

[36] Beach.  261.

[37] Ibid.  253.

[38] “Torpedo Data Computer” ( 23 January 2005.  Blair.  44.

[39] Named for the color book the code was written in as it was broken.  Hence the subsequent “Blue” codes and famous. “Purple” code.

[40] Blair.  31.

[41] A code is a simple this word or group of letters means that – Tiger  (Tora) = Success.  Encryption is the transposition of letters on top of the code.  This may be a linear encryption Y=T, or be driven by a complex mathematical algorithm.  NSA employs thousands of high level mathematicians to generate and break such algorithms.

[42] Ibid.  373

[43] Ibid.  xvii.

[44] Ibid.  373.

[45] Ibid.  107.

[46] Smith.  65.

[47] “Vice Admiral Charles B. Momsen” ( 23 January 2005

[48] “Air & Sea Search Radar” ( 23 January 2005

[49] Padfield.  29.

[50] Blair.  44.

[51] Hawkins developed surround sound for Disney’s Fantasia.

[52] Smith.  127.

[53] Ibid.  138.

[54] Padfield.  469.

[55] Ibid.  398.

[56] “Notices to Seamen” captured in the Gilberts Islands and Marshall Islands contained detailed maps.  Quickly translated, this information was issued in booklet form to all submarine commanders..  Bair.  561.

[57] Blair. 764.

[58] Smith.  273.

[59] Blair.  333.

[60] Wolf packs supported by air craft were shown to be 30 times more productive than those without air support.

[61] Smith.  141.

[62] Ibid.  124.

[63] Padfield.  32.