Friday, May 22, 2009


A pyrometer is an instrument for measuring temperatures too great for an ordinary thermometer. It is used to find the temperature of a fire. An important use of pyrometers is in checking the progress of a fire that cannot be seen, such as a fire that has been confined in a closed compartment or hold.

By taking readings at the same location at various times, one can tell if the fire is gaining or lessening in intensity. By moving the pyrometer to different locations along a bulkhead or deck, you can determine if the fire is extending laterally.

Pyrometers are attached to, or embedded in either of two types of bases. The usual type base may be placed on the deck over the fire space. The magnetic type can be "slapped" onto the outside of a bulkhead of a burning space. A chain should be attached to the base of the pyrometer. It can be used to pull the instrument across a deck that is too hot for personnel. It is also useful in lowering the pyrometer into a hot area.

A pyrometer can be useful in evaluating the success or lack of success when flooding a burning compartment with carbon dioxide. You should keep in mind that great patience is needed to successfully extinguish cargo hold fires with carbon dioxide. One cannot "take a peek" to see how things are going. Opening up would significantly dilute the extinguishing gas within the cargo compartment, which would destroying its effectiveness. Using a pyrometer and checking the variations in temperature should give you your information. A rising temperature after carbon dioxide has been introduced would indicate two possibilities:

1) the amount of carbon dioxide introduced is insufficient and more is required, or

2) the carbon dioxide is not reaching the fire (directed to the wrong fire zone, a control valve is closed or malfunction of the system). A steady lowering of the temperature would indicate that the carbon dioxide has either extinguished the fire or has it under control. However, though a steady lowering of the temperature is
observed or even if the temperature reading is down to 66°C (150°F) or less, these encouraging readings should not be interpreted as a signal to open the compartment. There should be no need to open a cargo hatch until port is reached. After all, the damage to the cargo has already been done by the fire.

Sunday, May 10, 2009

Captain Cook and Life at Sea

The crew of the first voyage was very experienced, and they were young, there weren’t many over the age of 30 years old. One man, Lieutenant Gore, had already circumnavigated the globe twice, under other captains. Five crewmen had been on an expedition that circumnavigated the globe once. Five other crewmen had sailed with Captain Cook before. On the second voyage, Lieutenant Tobias Furneaux, who had sailed around the world before, commanded a second ship, the Adventure. On the third voyage, Charles Clerke commanded the secondary vessel, the Discovery. Many who participated in the first voyage went along for the second, or the third, or both. An astronomer named Charles Green was aboard for the first voyage, to help Cook with his astronomical observations.
Captain Cook, dressed in the standard gentleman’s clothing of the day. He wore tight, fitted breeches with stockings and buckled shoes. On top, they wore white shirts with a vest called a waistcoat, and a long-sleeved jacket. Common sailors had the freedom to dress a little more casually. They wore slops, loose, short pants and shirts, and were not required to wear waistcoats or jackets. Many sailors did not even wear shoes on board the ship, becuase it was easier to climb in the rigging of the ship with bare feet.
The high-ranking members of the expedition, such as Captain Cook and Joseph Banks, had their own private cabins. They were not large, but they did offer the men a little bit of privacy. Much of the scientific work done on board the ship was also done in these private cabins. The sailors slept on the mess deck in hammocks. The mess deck is also where the sailors ate and relaxed.
One of Cook’s most important discoveries during his voyages was about food. Cook realized that there were certain foods that, if eaten, prevented the disease called scurvy. Scurvy, we know today, is caused by a lack of vitamin C in the diet. Scurvy was common among sailors, because most vitamin C comes from fruits and vegetables. Fruits and vegetables were very difficult to keep fresh during long sea voyages in the days before refrigeration. So, sailors before Cook’s time ate a diet that was mostly dried, hard bread known as hard tack, and dried, salted meat.
Cook took two major steps to change the diet of his crew. First, every time the ships stopped anywhere that grew fresh fruit and vegetables, he bought some to feed to the crew.
But, because there were sometimes weeks between stops, and fruit and vegetables would rot in that time, he had to have another plan. He knew that sauerkraut, which is pickled cabbage, had been shown to prevent scurvy. Sauerkraut, because it is pickled, can be kept in jars, and will not go bad. Cook brought a lot of sauerkraut on his voyage, but the crew didn’t want to eat it at first.
Captain Cook played a very interesting trick on his crew. When he realized that the men were refusing to eat the sauerkraut, he took it away from them. He said only the officers could eat it, and only put it out on the officers tables. Telling the crew they couldn’t have it made them want it more, so they started eating it.
Cook’s crew was out to sea for a longer period of time than any sailors before them. And yet, not one of Cook’s sailors died of scurvy. This means that Cook proved that certain foods could prevent scurvy, and sea captains after him followed his example and took sauerkraut, fruit, and vegetables on their voyages.
The captain had to make all the difficult decisions. He decided what course to follow, how punishments would be dealt amongst the crew, and, in Captain Cook’s case, he had the freedom to choose members of his crew as well as his ships. Captain Cook’s talents also led him to personally make maps of places he visited. Lieutenants ranked below the captain, but could be in command of their own ship. Furneaux was only a lieutenant when he commanded the Adventure. A lieutenant is someone who steps in “in lieu” of the captain. If the captain is incapacitated, on another ship, or busy with something else, a lieutenant can also make decisions on board, punish the men, etc.
Navigators used equipment that could determine the ship’s position in the world. They could take that information and, after knowing where the captain wanted the ship to go, plot the course. A navigator had to be an expert at using navigational instruments, and very good at math. Marines were on board Cook’s ship as well. While people in the navy could fight using the ship’s guns, marines were called upon for fighting that might happen on land. The boatswain was in charge of the rigging, he and his crew made sure the sails were set properly.
The carpenter was responsible for keeping the wooden parts of the ship in good shape. He worked on the masts and the hull. The carpenter on the Endeavour had a very important role, when the Endeavour wrecked on the Great Barrier Reef in Australia, if they had not had a good ship’s carpenter on board, they might not have been able to repair the ship and get safely home.
The quartermaster made sure the supplies on board the ship were distributed. If the ship ran low on supplies, he would decide whether or not to change the size of the men’s rations.
The cook had the job of feeding all the men on board. The cook on board the Endeavour had only one hand, which probably made his job very difficult. However, many sailors who had serious injuries would find themselves as cooks on board ships. It was a job they could still do, even if they had only one hand or one leg. The surgeon was a very important member of the crew. He kept the crew healthy while they were on board the ship. If a crewman was injured, he cared for him.
The following pay scale was for the Royal Navy. The exact pay of Captain Cook’s crew might have been a little bit different than this, when sailors would go on a voyage, their pay would be raised, because they were on such a risky mission. Able-bodied seamen, men who had two or more years experience at sea made about 14 pounds a year. Ordinary seamen, men who had between one and two years experience at sea, made 11 pounds, and landsmen, men who had less than one year of experience at sea, made 10 pounds. This was the pay scale for the British Navy from 1653-1797, when Royal Navy seamen got their first pay raise. Officers were paid much better, depending on what sort of vessels they were serving on.
Captains of first-rate ships made about 30 pounds a month, twice what able-bodied seamen made a year, captains of third-rate ships made about 20 pounds a month, and captains of sixth-rate ships made 16 pounds. A lieutenant made the same rate no matter what, 8 pounds a month.
What type of punishments did they have? On Cook’s voyages, not many crewmen required punishment. When they did, they were flogged, beaten with a cat o’ nine tails. There are no examples on board Cook’s ships of some of the more serious punishments, such as keel-hauling. The natives Cook encountered were dealt with differently, however. Cook was especially well known for being kinder than most European explorers to the natives. That did not mean he let them get away with doing mischief to his crew. When natives of various islands stole from his crew, he often had to fight them to get back the stolen property. During some of these skirmishes, Cook’s men shot native Pacific islanders for theft. Even this, though, was often an accident. The shots were made to warn and frighten, not to kill. But, sometimes the shots missed and people did die.

Sunday, May 3, 2009

Ka-Mal Navigation

Europeans did most of their sea trading along coasts that were near them, and mostly in an east-west direction. If they were out of sight of land, it was usually not for more than a few days. There was no need, and therefore no interest, in measuring distances north and south.

The Arabs, however, traded along the dangerous shoals (shallow waters) and strong currents off the coast of East Africa which ran from north to south, and as far off as India, out of sight of land most of the time. It was important for them to know how far north or south they traveled along an unseen coast before it was safe to turn toward that coast and make their landfall. The device they developed was called the Ka-Mal, which means “guide” in Arabic. Though very simple and “low-tech,” it was used by the Arabs of East Africa and the Red Sea as recently as the 20th century. We don’t know when it was developed, but sometime after 900 CE, a time we know the Arabs had the Astrolabe. It also seems the Arabs developed the Ka-Mal from a similar Chinese invention.

The Ka-Mal in its simplest form was a piece of wood; the navigator sighted the horizon at the bottom of the wood and Polaris at the top. When everything lined up, the ship was at the right Latitude to turn toward the city of their arrival. There would be a different piece of wood for each port. In time, the multiple pieces of wood were replaced by a single piece with a hole in the middle through which a string was fixed. A knot in the string, placed between the navigator’s teeth, would then set up the correct proportion of distance from the eye, and an alignment of the horizon and Polaris.

Each knot in the string represented the latitude of a port they wished to make, but they did not use that term or use a latitude-longitude system. Vasco da Gama, the Portuguese explorer, was introduced to the Ka- Mal when he visited India in 1498. This concept was taken up by the Europeans in the 1500s and led to their developing the Cross-Staff.