International Journal of Naval History

Computer Methods for Investigating CV Taihō

Richard Wolff, U.S. Department of Energy

Abstract

The author is in the process of writing a book tentatively titled Anatomy of the Ship: The Fleet Aircraft Carrier Taihō.”  This project has involved a number of computer methods to categorize, illustrate, translate and postulate facts and data found in historical records.

This paper will show how simple computer methods like tables and lists can identify previously unnoticed historical details.  It will also be shown how popular drawing programs such as Adobe Illustrator can identify and correct errors in plans of warships.  The author will explore the use of 3D visualization software and how it can add realism to warships lost in battle and nearly lost to history.  It will be shown how 3D drawing software can also confirm details such as ship displacements under varying loads. 

Introduction

Between 1939 and 1944, the Japanese Navy designed and built their most advanced aircraft carrier, Taihō.  Within 3 months of her completion, this ship was destroyed in battle from a massive aviation gasoline explosion after a single torpedo impact.  As the Pacific war ended, most of the technical information, plans and operational details for Taihō were destroyed either by Allied bombing or by the Japanese military itself.  Some technical documents were collected by the Naval Technical Mission to Japan immediately after the war’s end and copies of much of this material is available in the U.S. National Archives [1].  But many of the materials inventoried and indexed by the Naval Technical Mission were subsequently lost.  These various events or circumstances have resulted in a scarcity of information and in many questions regarding this shi  This paper discusses the use of computer methods to verify the remaining details and to extrapolate this scant and often conflicting information into detailed plans.  The intent is not to explain how to use various computer programs but rather how these programs can help in the investigation of naval history.  The examples draw on the author’s own experience and on the work of colleagues.  The techniques and examples are categorized by the following classes of computer applications:

o       tables and lists

o       drawing software

o       imaging programs

o       3D visualization software

o       internet access and sites

As an aside, please consider a leading source for records and evidence pertaining to naval history.  The U.S. National Archives is an amazing repository.  But the thing that is so challenging about NARA is that one can find just about anything if you can only provide the index information.  The encyclopedic volumes filled with abbreviated index titles fill entire rooms.  And although NARA staff has started the enormous task of computerizing this index information, the light at the end of that tunnel is not yet visible.

The whole experience has pushed me to predict what records might exist and where they might be stored and then to try to find them.  I call this the needle in the haystack problem.  If you can't define or describe the needle, you'll never find it in the haystack of historical records.  This is the concept that I'm using in my Taihō research.  I propose a reasonable theory based on known facts and then go looking for the proof.  Some of the computer methods presented in this paper have resulted in answers but even more often they present an idea in want of supporting evidence, a picture of a needle to be found in the haystack.

Tables and lists

Lists are the nucleus of any sort of reporting or record keeping whether the subject relates to naval history or programs on television.  Focusing on warship characteristics, one might start by listing all known battleships built or planned.  But as additional data is added pertaining to each of the battleships, such as country that built the ship or the size of guns, the list becomes a table.  These are ancient methods.  But when a computer is utilized to maintain the list or table of information, it becomes possible, even simple, to rearrange the information in a way that might yield valuable insights.

Example: IJN ship building data

There are a number of references available that contain data about each warship built by the Imperial Japanese Navy.  Such a book is “The Imperial Japanese Navy” by Anthony Watts and Brian Gordon [2].  This book is notable for its Appendix I which lists the Japanese ship building programs from 1937 onward, with the order of the data first by building program and then by ship order number.  The ship order number is very useful because it tends to be very sequential and is intuitively useful for a computerized list.  But this book as well as many others also contains additional detailed data for each warshi  As a starting point for familiarization with the ships of the Japanese Navy, it is useful to record such details as building yard, start date, launch date, and completion date as well as the basic data of ship name, type, class, and so on.  The following table is a representative sample from such a computerized list, created using a spreadsheet.

Of course, this table shows slices from a more complete list of data.  Even with this shortened sample, there is not much in the way of surprises that jump out of the report.  Three of the four Agano class cruisers (numbers 132, 134, and 135) were built at the Sasebo Navy Yard.  Because these ships are in a close sequence in the list, it is noticeable that the start and launch dates for these ships do not overlap with each other and in fact have a reasonable space of 20 and 26 days between the launch of one ship and the start of another.  There is a strong implication from this observation that these ships were likely built in sequence on the same sli  This begs the question of other sequences of ships constructed one after the other.  This question becomes very relevant if one considers that any delays in the construction of one ship up through its launch could impact the start and therefore the completion of the next ship in the sequence. 

The characteristic of computerized lists and tables that is so important to the study of naval history is that the data can easily be reordered based on a component of the data.  If this table is sorted first by the building shipyard and then by the date that the ships were laid down, the resulting table could present other relationships between the ships being built.  Consider the following reordered table:

Indeed, this new ordering does present several hints for further study.  The start of the battleship known as hull