The Sultana – Part 3: Did careening cause the explosion?

In a previous post, I discussed the extent of engineers’ knowledge in the mid-1800’s and compared that to today’s knowledge of boiler explosion science. Probably the most commonly cited theory of the explosion of the Sultana is a combination of low water and careening of the boiler.

Careening theory

According to this theory, the water level was low and as the boat rocked, or careened, the boiler iron was exposed to the heat of the fires without water covering and cooling it. The iron turned red hot and when the boat rocked back, the water striking the metal flashed to steam creating a sudden pressure surge and subsequent explosion.

The emphasis and acceptance of this explosion theory is due to the large amount of testimony that discusses careening and low water. In testimony or affidavit, Isaac West (Boilermaker and Engineer), WB Richardson (Chief Engineer of the steamboat Marble City), JJ Witzig (supervising inspector of steamboats, St. Louis), RG Taylor (boilermaker) and Sultana Chief Engineer Nathan Wintringer all noted that careening of the boiler may have been the cause of the explosion. Four of these individuals were not on the boat and the fifth, Chief Engineer Wintringer, was asleep at the time of the accident.

Union Captain Frederic Speed was court-martialed for his role in the overloading of the boat. The prosecution at his trial asked multiple questions regarding careening of the boat. Due to the large number of troops on board and the small amount of cargo in the hold, the boat did rock to one side when many men rushed there, notably during the last picture (above) taken of the Sultana in Helena, Arkansas.

Low water an unlikely cause

In 1865, boiler engineers, captains and others in the trade believed that a boiler full of water could not explode. This was stated directly in the affidavit by R.G. Taylor: “So long as there is a sufficiency of water in the boiler there is no danger of explosion.” Therefore, when reading the testimony of the engineers, it is important to understand that they did not have today’s knowledge of steam theory or why boilers explode.

As the science behind the immense power of steam explosions became known, the pendulum swung the other way. By the late 1800’s, some believed that no explosions were caused by low water. Calculations show that the amount of steam generated from red hot steel is insignificant compared to that generated from a simple depressurization of the boiler.

Evidence contradicts theory

Maintaining a proper water level is critical to ensure that the heat absorbing tubes are covered in cooling water and generating steam. The engineer on duty the night of the accident was Samuel Clemens (not the famous author), who died shortly after the accident of the injuries he received.

According to Wintringer, Sam Clemens had been working around boilers for about 25 years, and the chief engineer considered Clemens an able engineer. He clearly understood the need to maintain a full boiler. It was reported that he stated the boilers had been full of water.

In his short testimony before he died, he did note that as the boat was light, it did roll during the trip. Even though Clemens noted that the boat was light and rolled, he did not place the blame on low water.

Calm before the storm

“All was at peace and no sign of disaster. I spoke to the engineer of how nicely we were going…” stated George Clarkson, a survivor who was awake at the time of the explosion. If the boat were rocking enough to expose the bottom of the boiler for a period of time long enough to heat it to red hot, it would have been noticed.

At the time of the explosion, the men were mostly asleep and not moving side to side as mentioned in the careening theory. There was no mention in any of the survivors’ stories of a rocking boat before the explosion. In a letter to the Secretary of War, dated May 19, 1865, General Hoffman, one of the Army investigators, noted that, “There is nothing to show that there was any careening of the boat at the time of the disaster, or that she was running fast; on the contrary, it is shown that she was running evenly and not fast.”

The testimony of the experts stated that it was likely careening and low water in the boilers that caused the explosion, and this was accepted as fact. We now know that they did not understand how or why boiler explosions were so powerful nor why they most commonly occurred. Soldier recollections and other testimony indicate that the boat was not rocking.

Therefore, the focus should be on how explosions occur based on current knowledge of boilers. The next post will discuss “Occam’s razor.” Occam’s razor states that when evaluating competing explanations, the simplest explanation is usually the best answer.

 

© 2015 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is intended for information purposes only. HSB makes no warranties or representations as to the accuracy or completeness of the content of this article.

Patrick Jennings

Pat is the go-to engineer for boilers at HSB. He has been crawling around, studying, talking and writing about boilers for almost 30 years.

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