Category Archives: Naval History

Web Scraping WW2 Landing Ship Data

Posted on 12-August-2018 by mathscinotes

I have been working on improving my web scraping abilities by analyzing WW2 data. I have focused on topics related to how the US took the 14th largest military in the world and in roughly 18 months turned it into a military that could fight anywhere in the world. In this post, I want to look in detail at how war materials were delivered to beaches around the world using a vessel called a Landing Ship Tank (LST). I have wanted to write about the LST for a while, but the web data was distributed on about 1200 separate pages – one for each ship. While a Python script would have worked nicely, I wanted to try gathering the data without doing any programming. I found some software that did a good job automating this task, which I will discuss later in this post. Continue reading →

 
Posted in History Through Spreadsheets, Military History, Naval History | 2 Comments

Liberty Ship Production Data

Posted on 22-May-2018 by mathscinotes

One WW2 battle that we hear little about was fought by logisticians. Their battle was between what could be produced versus what could be delivered in time to matter.  This point was driven home to me when I heard a WW2 historian say that the US had the manufacturing capacity to produce 150K tanks, but that level of tank production would consume all the US steel and leave nothing to build the ships needed to carry the tanks to the fight. Continue reading →

 
Posted in Excel, History Through Spreadsheets, Naval History | 2 Comments

Earth's Curvature and Battleship Gunnery

Posted on 20-December-2017 by mathscinotes

I must admit that I am a bit of a battleship junkie. I have been reading some old US Navy manuals on battleship fire control, which discuss the various effects that must be corrected for to ensure accurate fire (Figure 1). In this post, I want to examine how the curvature of the Earth affected the gunnery direction. Curvature corrections are only needed for very long-range artillery. Continue reading →

 
Posted in Ballistics, Naval History | 84 Comments

Torpedo Engine Technology for a Venus Space Probe?

Posted on 24-October-2017 by mathscinotes

I just finished reading an interesting article on a NASA proposal for a Venus space probe that uses power generation technology developed for a US Navy torpedo program back in the 1980s. Like many spacecraft, torpedoes need power generation systems that are small, generate massive power for a short period, and must be storable for years with the ability to turn on almost instantly with high reliability. Continue reading →

 
Posted in Naval History, Space | Leave a comment

WW2 Submarine Endurance on Batteries

Posted on 16-February-2016 by mathscinotes

I have been reading the book The Bravest Man, a biography of the WW2 exploits of US Navy submarine commander Dick O'Kane. I have not formed an opinion on the book since I just started reading it, but the book does highlight the submerged maneuvering limitations imposed on a ww2 submarine because of its lead-acid battery-based power plant. The book's discussion made me curious about the operational characteristics of a Gato-class submarine when operating submerged on batteries. In this post, I will be examining the Gato-class submarine's run time versus speed plot (Figure 1). Continue reading →

 
Posted in Naval History | Leave a comment

The Bounty Mutiny and the Pitcairn Island Position Error

Posted on 5-February-2016 by mathscinotes

I liked reading the book Longitude by Dava Sobel and I also enjoyed the television movie version. I was recently doing some reading about the Bounty mutiny when I realized that the problem of measuring longitude played a role in that tale as well. The story of longitude is one of technology and obsession. While mariners had been able to measure their latitude accurately for centuries, measuring one's longitude required the development of accurate timepieces. Longitude is the story of the development of the marine chronometer. In essence, our modern GPS systems are extremely accurate clocks that provide the ultimate realization of the longitude goal. Continue reading →

 
Posted in Naval History, Navigation | Leave a comment

Index/Instrument Error Correction in Sextant Measurements

Posted on 31-October-2015 by mathscinotes

Sextants make measurements that are subject to systematic errors – all instruments are subject to systematic errors. Alas, much of my career has been spent on calibrating out systematic instrument errors. Even with all my efforts, residual systematic errors remain. Continue reading →

 
Posted in Naval History, Navigation | 2 Comments

Refraction Error Correction in Sextant Measurements

Posted on 27-October-2015 by mathscinotes

Refraction is probably the most difficult to understand of all the altitude observation corrections. It is also the most difficult to estimate accurately because it depends so strongly on atmospheric conditions, particularly the rate of temperature variation with altitude (see lapse rate). I will derive in this post a commonly used expression for the refraction correction required for a celestial object with an altitude greater than or equal to 15°. The accuracy of this expression degrades significantly for objects below 15°. Continue reading →

 
Posted in Astronomy, Naval History, Navigation | 3 Comments

Correcting for Sextant Parallax Error

Posted on 24-October-2015 by mathscinotes

Navigators use the altitudes of solar system objects to assist them with determining their positions. The most commonly used solar system objects are the Sun, Moon, Venus, and Mars. There is a small error caused by the fact that navigators are making their sextant measurements from the surface of the ocean and not from the center of the Earth, which is the reference point used by nautical almanacs. Parallax has no practical significance when measuring the positions of stars because they are so far away relative to the radius of the Earth. Continue reading →

 
Posted in Astronomy, Naval History, Navigation | 1 Comment

Correcting Sextant Measurements For Dip

Posted on 21-October-2015 by mathscinotes

I love to read stories of the sea and about the voyages made during the age of sail. I personally have never thought that I would have an opportunity for ocean sailing, but I recently began working with an engineer who is an avid sailor and teacher of sailing. He has sailed all over the world and recently trained another engineer in my group to sail. This newly trained sailor just returned from a trip to Bora Bora, which he found to be enjoyable and the sailing uneventful. Continue reading →

 
Posted in Naval History, Navigation | 8 Comments