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How Likely was a Coal Bunker Fire Aboard the Battleship MAINE?

By Patrick McSherry

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Many articles and studies concerning the loss of the Battleship MAINE base their analysis on the existence of a fire in one of the MAINE’s coal bunkers (coal storage rooms), namely coal bunker A-16. It is often claimed that a fire in the coal in coal bunker A-16 was the heat source that caused the powder in the neighboring reserve six inch ammunition magazine to explode.

In fact, no one has ever been able to provide any evidence in the form of statements of witnesses or forensic evidence showing that a coal bunker fire actually existed. The evidence available actually indicates the opposite - that a coal bunker fire was not likely. The following discussion looks at the evidence available supporting this conclusion.

The Discussion:

1. Coal Type

The probability of a coal bunker fire varies significantly with the type of coal being stored. Some coals are higher in volatile content than others. Volatile content is the amount of volatile matter in the coal that is not in the form of fixed carbon, such as sulfur. The higher the amount of volatile material in coal, the more likely the coal will suffer from spontaneous combustion1 . Coals with high volatile matter are the low grades of bituminous (“soft”) coal whereas coal with low volatile matter content tend towards anthracite (“hard”) coal2.  In its 1898 study of spontaneous combustion of coal, the U.S. Navy reported “…spontaneous combustion is confined to bituminous coal or ‘soft’ coal, inasmuch as we have not learned of a case of fire due to the cause in anthracite coal on shipboard…3

What was the type of coal that was stored in Coal Bunker A-16 on the MAINE? The type of coal will be a strong indicator of the likelihood of a bunker fire. The coal in the bunker was either Pocahontas coal or New River coal 4. Frank Bowers, the MAINE’s First Assistant Engineer stated that the coal was probably Pocahontas coal5 but the final conclusion of the Sampson Board was that it was New River coal 6.

Coals are classed into various categories based on the percentage of volatile matter that the coal contains. The following table gives the various classifications and the percentage of volatile matter for the basic coal types7. Low volatile bituminous coal (also known as “semi-bituminous” to indicate its difference in chemical composition from other bituminous coals8) was the classification that included the Pocahontas and New River coals, the type of coal found in coal bunker A-16. A study of close to 8,500 samples of New River and Pocahontas coals (coals from the New River and Pocahontas coal beds of West Virginia) indicated a volatile matter content of about 18 to 19 percent for Pocahontas coal and 20 percent for New River Coal9. New River and Pocahontas coals were known as “smokeless coals” and the characteristics of the coal “…placed it in a category that was separate and distinct from all other classes of bituminous coal…While the sellers of anthracite coal could boast of its 6-8 percent volatile matter, the smokeless coal of Southern West Virginia provided a very close match to the anthracite coal10.” The low volatile bituminous coal in MAINE’s A-16 coal bunker was therefore a coal that approached the quality of anthracite coals, or, simply put, coal that approaches the qualities of a coal known not to represent a strong danger of spontaneous combustion.

Coal Type
% Volatile Matter
Pocohontas Coal 18-19
New River Coal 20
Low Volatile Bituminous
Medium Volatile Bituminous
High Volatile Bituminous

A table showing the percentage of volatile matter in various types of coal. The greater the amount of volatile matter, the more likely the coal is to suffer from spontaneous combustion. Anthracite was not generally known to spontaneously combust. MAINE’s coal bunker A-16 was loaded with New River or Pocahontas coal.

2.  Length of time the coal was in the bunker.

A second major issue which would have an effect on the possibility of spontaneous combustion was the length of time that the coal was in the coal bunker. Spontaneous combustion is more likely to occur in newly-mined coal, rather than coal that has been aged. Spontaneous combustion, it should be explained, occurs on the surfaces of freshly broken coal. The newly exposed coal surfaces oxidize. As this occurs, heat is given off. If the heat is not dissipated, it can build up. Eventually, the heat will rise to the point of combustion, about 180 degrees Fahrenheit11, and the coal will begin to burn. This process is quite slow, unless there is an outside heat source to speed it along. However, the longer the coal surfaces are exposed, the less the chance of spontaneous combustion occurring, since the surfaces should already have been subjected to oxidation. In 1898, the U.S. Navy’s study on spontaneous combustion of coal indicated that to avoid this problem “…coal should be a least a month from the mine12.” Other sources indicated that “The likelihood of spontaneous heating decreases during the first three months of undisturbed coal storage. Thereafter, the coal is stable if not handled and self-ignition would be unlikely13.”

The question arises then, how long was the coal in bunker A-16 out of the mine? The coal in coal bunker A-16 was loaded at Newport News, Virginia, prior to the ship being drydocked at Norfolk14. This was significant, since much of the MAINE’s coal had been loaded at a later date. MAINE had been at Newport News on November 21st through the 23rd, 1897. The explosion occurred on February 15, 1898. Therefore, even assuming that the coal had been mined, immediately delivered to Norfolk, and then immediately loaded aboard MAINE, the coal in the bunker had been in place for over two and a half months. This is over double the amount of time recommended as a safe amount of time in 1898.

In short, the coal in bunker A-16, though not of a type of coal prone to spontaneous combustion, and even if it was prone to spontaneous combustion, it was well beyond the critical period in which spontaneous combustion was likely to occur.

3.  Coal bunker location

One of the major concerns about coal bunkers aboard ships, particularly warships, was that coal bunkers often flanked the boilers. In warships, this was done purposely as the coal acted as armor, protecting the boilers from shell and torpedo fire. However, the heat from the boilers had a tendency to accelerate the oxidation in the coal, making the bunkers adjacent to boiler rooms more prone to spontaneous combustion. “The danger point is usually considered to be about 100 degrees F. although a higher point must be reached before actual firing, about 180 degrees F15” according to one source. Another states that “Coals with a temperature of 160 degrees F or less that are trending stable or declining temperature are generally not going to overheat. Coals that are 180 degrees F and above and are trending stable or increasing in temperature need immediate attention16.” Another source, the 1898 study on spontaneous combustion, states that if “the bunker coal next to the bulkhead  be kept at 120 degrees F., any coal with a tendency to absorb oxygen will run a great chance of igniting within a few days17.”

In the case of the MAINE, was there an external heat source? No, there was not. The only boilers functioning in the MAINE were those aft. Coal bunker A-16 was forward. There was no other source that could act as an outside heat source to drive spontaneous combustion in coal bunker A-16.

Basically, coal bunker A-16 was not a likely place for a coal bunker fire to occur. A coal bunker fire would have been much more likely in a coal bunker adjacent to a heat source.

4. Initial temperature in the coal bunker.

Since initial coal temperature is an important factor, do we know what the temperature was in coal bunker A-16? Maybe the bunker was unusually hot, leading to spontaneous combustion.

In fact, apparently the temperatures were quite low. On the day of the explosion, the temperature of the coal bunker was recorded at 59 degrees F18.  This was far below the level that would have presented a danger of spontaneous combustion. It should be noted that temperatures in the lower parts of the ship were fairly constant. Heat was dissipated through the steel bulkheads and structure, through the hull and into the sea. In essence, the temperature of the sea moderated the temperatures in these areas of the ship. Based on the known data, the temperature in coal bunker A-16 was significantly below the level of the temperature danger point.

5. Signs of a coal bunker fire.

If a coal bunker fire did occur in coal bunker A-16, how would anyone have known? This discussion requires a bit more understanding about coal bunkers in general. Coal bunker fires were not an unknown event or even one that created panic. Bunker fires, on some ships, were even common. The naval crews knew the tell-tale signs of a bunker fire, and were cautious to keep watch for them.

First, the MAINE’s coal bunkers were equipped with a temperature sensor system. The MAINE’s sensor system was functioning at the time of the explosion. In fact, Frederick Bowers, the MAINE’s first assistant engineer reported to the Sampson Board the system did not work well, since it went off even when bunkers were empty19. This meant that the system was too sensitive, and more likely to give a false positive report rather than not report at all.

Coal bunkers were inspected daily for signs of coal bunker fires. Assistant Engineer John Morris had inspected coal bunker A-16 between 10:00 and 11:00 on the morning of the explosion and found no unusual heat. Furthermore, Morris inspected coal bunkers B-4 and B-6, which were adjacent to A-16 at 7:45 on the evening of the explosion – less than two hours before the explosion itself. He had not entered, but looked into B-4 and B-6 at this time20. Bunkers B-4 and B-6 were recently repainted21. Still Morris felt no unusual heat, and saw no redness, and smelled nothing unusual such as burning coal or burning paint from intense heat. Any or all of these items should have been sensed if there was a fire deep in bunker A-16 close to the steel bulkheads in these bunkers, which were empty.

In addition, Chief Engineer Holman pointed out that if there was a fire deep in the bunker, the heat should have been felt through the escape hatches on the coal bunker walls. No heat was felt, however. Private William Anthony of the MAINE’s Marines noted that when he passed down the wing passage, he found that one of the “dogs,” or heavy brass latches, on bunker A-16’s escape hatch was open. He closed it noting that he felt no unusual heat22 and apparently did not sense the smell of burning coal.

Of course, the easiest way to find a bunker fire did not even require an inspection of the interior of the bunker. Bunker A-16 was several decks high. Its confining steel bulkheads were exposed in many locations. The radiation of heat from a coal bunker fire with expected temperatures of 700 degrees Fahrenheit would radiate through the steel bulkheads, and would be felt by those passing by. On two decks, the majority of the outboard side of the bunker shared a bulkhead with a narrow wing passage. Men of the engineering department who toiled in this area of the ship, had a practice of touching the bulkheads in these areas feeling for unusual heat which would indicate a bunker fire.  Chief Engineer Charles Howell indicated that “Every time I go through the wing passages, I pass right by the bunkers. I have never gone through without putting my hands on them [the coal bunker bulkhead] to feel the temperature. I never found any signs of heating23.”

Other bulkheads were exposed elsewhere. The inboard bulkheads of coal bunker A-16 were exposed in the dynamo room, and the engineer’s storage area. The ends were exposed aft in bunkers B-4 and B-6, which we know from John Morris’ testimony exhibited no signs of heating24. The forward bulkhead was exposed in the paymaster’s storage area25. Other surfaces were exposed on the platform deck. The bunker temperature therefore could be monitored from those locations26. Yet no heat was detected.

On other ships where bunker fires were reported, such as on the BROOKLYN, OREGON, CINCINNATI  and NEW YORK27, the smells of burning coal and smoke and the smoke from charring wood in adjacent compartments helped alert the crew to a fire. No smell or smoke was found when coal bunker A-16 was inspected on the day of the explosion. None of the crew who would have passed the vicinity of the coal bunker made any reports of smells or smoke even though they were in the vicinity as recently as two hours before the explosion.

Keeping in mind that since coal bunker fires are slow growing affairs, not flash fires, there was ample time to detect a fire. Yet coal bunker A-16’s temperature sensor did not indicate the heat from a coal bunker fire. The coal bunker had been inspected the morning of the explosion, and no fire was detected. The exposed surfaces of the steel bulkheads around the coal bunker, though monitored frequently, in some cases almost continuously, no unusual heat indicating a bunker fire was ever reported. Engineering staff reported that they were checking coal bunkers in the vicinity of A-16 within two hours of the explosion, and found nothing unusual. Lastly, the tell-tale smells of smoke and smell of burning coal or wood were reported by none of the crew. There is no evidence anecdotally or physical of a bunker fire in 1898 or now.

6.  MAINE’s history of coal bunker fires

Did the MAINE have a history of coal bunker fires? Does it matter if the MAINE did or did not have a history of coal bunker fires?

MAINE had no history of coal bunker fires, and this is an important fact.

First Assistant Engineer Frederick Bowers was asked by the Sampson Board inquiry if the MAINE had ever had a coal bunker fire. He reported that she did not28.

Some ships repeatedly had difficulties with coal bunker fires, whereas others did not. The problems, oftentimes, were a function of the specific design of the coal bunkers, their ventilation, and their proximity to other spaces. Some ships, such as the OREGON, had as many as four bunkers ablaze simultaneously29. The MAINE, in contrast, never had a coal bunker fire in her history. The lack of a history of bunker fires on MAINE is significant.

7.  Coal handling.

Was the coal aboard the MAINE handled and stored correctly? If it wasn’t, could this contribute to the possibility of a bunker fire? In fact, the MAINE probably had a level of safety in coaling that was not experienced aboard most ships of the period. The MAINE’s executive officer was Richard Wainwright. Wainwright had been ordered aboard MAINE when she was in Norfolk30.  Richard Wainwright was an extremely conscientious officer who had served as the chief of the Office of Naval Intelligence31. At the Office of Naval Intelligence, Wainwight had studied spontaneous combustion coal fires, and even prepared a paper on the subject for Assistant Secretary of the Navy, Theodore Roosevelt32. As a result, Wainwright had more expertise on the subject than virtually anyone else in the navy, and he would have been particularly careful in the storage of the coal.

In addition, the quality of the coal was inspected prior to its being loaded aboard ship by Assistant Engineer Frederick Bowers, and the coal and was found to be acceptable33.

8.   The coal bunker fire and views of the Sampson Board, the Vreeland Board and the Rickover study.

Why did the Rickover study determine a coal bunker fire was present when the 1898 Sampson Board and the 1911 Vreeland Board did not? The answer to this may lie in the expertise of the three boards. First, the Sampson Board had several members who had experience with coal bunker fires or even had an expertise in the matter (Chadwick, Potter). The Vreeland Board had Commander Charles Hughes who was an expert in naval equipment, including coaling and the problems of spontaneous combustion34. By the time of the Rickover study, those men who were familiar with the issues of coal had been long gone as the navy had passed through the coal era into the diesel era, and was now entering the nuclear era. The Rickover group (Hansen-Price) had no experts on coal bunker fires and spontaneous combustion.

Interestingly, the two boards who had expertise in coal bunker fires concluded that there was no evidence to suggest one existed on the MAINE. The group that had no expertise in coal bunker fires – Rickover/Hansen Price – determined that one occurred though there was no evidence indicating that one existed.

9.  More recent studies.

Have there been any other more recent studies? What was their view concerning the coal bunker fire possibility? Actually, there have been other recent studies that support the conclusion that a coal fire did not cause the explosion of the MAINE’s magazines.

In 1998, the National Geographic Society funded a study that used modern computer-based modeling systems to analyze which was a more likely cause for the MAINE’s loss – a coal bunker fire igniting a magazine or an external mine igniting a magazine. The result of the extensive analysis completed by Advanced Marine Enterprises indicated that either cause could have been the source, but “it appears more probable than was previously concluded that a mine caused the inward bent bottom structure and detonation of the magazines35.”

Interestingly, the report concludes this in spite of inadvertently having some of the initial assumptions for the study inaccurately set in a manner that would favor a coal bunker fire. For the study, the analysis set the temperature in the bunker at 100 degrees Fahrenheit. From the records, we know that the initial temperature of the bunker was recorded at 59 degrees Fahrenheit the morning of the explosion36. The National Geographic report indicates that the rate of oxidation will double for every fifteen to twenty degrees increase in temperature37. Based on this, the study had the initial rate of the heat-generating oxidation reaction occurring at least at four times the rate that probably actually existed! Still, the report acknowledges that the heat build-up “could not have been in progress for than a few hours prior to the last temperature check on the magazine38.” Coal bunker fires grow slowly, so this is very important conclusion. The result generally indicates that coal bunker would have had to have progressed at a tremendously fast rate, however, there was no source of outside heat to propel the fire at an accelerated rate, making the argument even less likely. Coal bunker fires were not rapidly progressing affairs.


It has been the mantra of historians to claim for the last quarter century that the evidence supports a coal bunker fire. Yet, no evidence of a coal bunker fire exists. Yet, there is documentary evidence and scientific evidence to indicate that a coal bunker fire aboard the MAINE was unlikely:

1. The coal type was of a type in which bunker fires would not be expected.

2. The coal in the bunker where the fire supposedly occurred was in the bunker beyond the critical period in which a bunker fire, if it would occur, would be expected.

3. There was no external heat source in the vicinity of the coal bunker that would cause or accelerate oxidation and a bunker fire. Coal bunkers in the vicinity of a heat source exhibit a greater likelihood of spontaneous combustion.

4. The temperature of the bunker was recorded on the morning of February 15, 1898, and was quite low, giving no indication of a bunker fire. The bunker was inspected at this time.

5. The MAINE’s over-sensitive temperature system did not indicate a coal bunker fire was present.

6. Coal bunkers adjacent to A-16 were inspected about two hours before the explosion, and no indication of excess heat was found.

7. The bulkheads around much of bunker A-16 were accessible, with some being on the oft-used wing passage. No unusual heat was felt on the bulkheads.

8. No smoke, or smell of fire was found issuing from either coal bunker A-16 or the reserve six inch magazine.

9. MAINE had no history of coal bunker fires, whereas other ships did. She had no recorded coal bunker fire during her career.

10. One of the navy’s experts on coal bunker fires – Richard Wainwright – was the executive officer of the MAINE, and would have been more sensitive than most other navymen to the tell-tale signs of a bunker fire, and the in methods used to avoid them.

11. The Sampson Board of 1898 and the Vreeland Board of 1911 both had members on them who were experts in coal bunker fire, how they formed, how they grew, their tell-tale signs, and the their results. These two boards determined against the theory that a coal bunker fire was the cause. Their findings are supported by the 1998 National Geographic analysis. The 1975 Rickover study had no one on the team who was an expert in coal bunker fires, but this team determined the cause was a coal bunker fire.

12. There has never been a single piece of physical evidence or anecdotal evidence supporting a coal bunker fire.

Does this mean that a mine had to have sunk the MAINE? Not exactly. At present, the mine theory remains the most viable theory if the loss of the MAINE is approached from a scientific basis. Of course, all parties now recognize that the Spanish government had nothing to do with the sinking, even if there was a mine involved. However, all the above really indicates that a coal bunker fire was not likely aboard MAINE. The mathematical probability of a coal bunker fire occurring in coal bunker A-16 in view of all of the items listed above is so low as to become virtually impossible.  It does leave open the possibility of other accidental events occurring aboard the ill-fated ship.

A good historian keeps his/her mind open, reviewing each new theory from an historical and scientific basis. However, they do not let stand theories for which the evidence does not exist. Such is the case of the coal bunker fire theory aboard the Battleship MAINE.

1. Rigsby, Lee, “What to Do While Waiting for the ire Trucks to Arrive (Avoiding Coal Stockpile and Bunker Fires)”

2.  “Trace Elements in West Virginia Coals”

3.  Griffin, Lt. Thomas, USN, Passed Assistant Engineer W. M. McFarland, USN, and Tos. Westesson, Chemist, “Report of Board on Investigation on the Spontaneous Ignition of Coal” (Washington: Department of the Navy, January 27, 1898) 81.

4.  Samuels, Harold and Peggy, Remembering the MAINE. (Washington DC: Smithsonian Institution Press,  1995) 147, from Capt. Royal Bradford, Chief of Bureau of Equipment.

5.  Samuels, 213.

6.  Sigsbee, Capt. Charles The “Maine,” Personal Account of Capt. Sigsbee. (NewYork: The Century Company, 1899) 209.

7.  Trace Elements in West Virginia Coals.

8.  Wadleigh, F. R., A Coal Manual for Salesman, Buyers and Users. (Cincinnati: National Coal Mining News, 1921) 12.

9.  Wadleigh,  80.

10.  “Smokeless Coal of the New River Coalfield”

11.  Wadkeigh, 163.

12.  Griffen et al, 83.

13.  Samuels, 302 from Scientific American (“Coal Piles that Light Themselves,” 1924).

14.  Samuels, 44.

15.  Wadkeigh, 163.

16.  Rigsby.

17.  Griffen, 83.

18.  Samuels, 147 quoting testimony of Chief Constructor Philip Hichborn.

19.  Samuels, 213, quoting testimony of First Assistant Engineer Frederick Bowers.

20.  Samuels, 213, quoting testimony of Assistant Engineer John Morris.

21.  Blow, John, A Ship to Remember. (New York: William Morrow and Co., Inc., 1992) 139

22.  Blow, 140.

23.  Samuels, 203, quoting testimony of Chief Engineer Charles Howell.

24.  Rickover, H. G., How the Battleship MAINE was Destroyed. (Annapolis: Naval Institute Press, 1976) 58, 110.

25.  Rickover, 58, 110.

26.  Samuels, 203, quoting testimony of Chief Engineer Charles Howell.

27.  Samuels, 137.

28.  Samuels, 213, quoting testimony of First Assistant Engineer Frederick Bowers.

29.  The Diary of George W. Robinson, Spanish American War Centennial Website,

30.  Samuels,  44

31.  Samuels, 86.

32.  Samuels, 134.

33.  Samuels, 213, Quoting Bowers’ testimony.

34.  Samuels, 264.

35.  Allen, Thomas B., “A Special Report - What Really Sank the MAINE,”  National Geographic. (February, 1998)

36.  Samuels, 147 quoting testimony of Chief Constructor Philip Hichborn.

37.   Allen,

38. Allen


American Navy, The. (Chicago: Geo. M. Hill Company, 1898.) (image).

Green, Nathan C., The War with Spain. (Baltimore: International News and Book Co., 1898).

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