June 25, 2001
Latitude: 38° 54 18 S
Longitude: 77° 02 18 W
Temperature: 32.2° C (90° F)
Wind Chill: Wishful thinking
National Geographic Headquarters, Washington, D.C.
Culture shock. Those are the first words that come to mind to describe my return. Soon to follow are heat, haze, humidity, air-quality index, and traffic.
The dock rock, a term used to describe the process of acquiring ones land legs, lasted a week. The haze mentioned earlier describes both the weather and my mental state. A haze prompted partially by leaving the close quarters and closed community of the Palmer, and partially from the abrupt end to a seven-day-a-week, 24-hour-a-day extremely tight focus on science.
I spent Fathers Day with my wife and sons and Riley the springer spaniel at my in-laws farm in Virginia. The haze cleared for me then. I sat in the grass watching and listening as a thunderstorm rolled in. It spoiled the plans for a little pond fishing, but in the 15 minutes I watched, it provided some closure. The grass bent to the pre-storm winds as the geese, peacocks, hens, and roosters clucked and crowed. It occurred to me, as I watched and listened, that this was the opposite of my experience of the past six weeks. I was back in the world of the known, the familiar.
For me, the cruise to Antarctica was a journey into the unknown. For the captain and crew, its a way of life. For the scientists, it is a chance to further the body of knowledge of this powerful yet fragile ecosystem. With the data being collected on the cruises of the SOGLOBEC investigation of the Western Antarctic Peninsula, a baseline is being set. That baseline will enable scientists to better understand the processes of the Southern Ocean and to create models to help predict the different futures that could evolve there.
Remember, this investigation was only a beginning. Thanks for following along. And thanks to the National Science Foundation for funding this extremely important research.
Mark Christmas, nationalgeographic.com field producer
Driving down the street near my home in Falls Church, Virginia, the other day, who did I see walking down the sidewalk? Ice pilot Vladimir Ripin and his wife, Galena, who were out walking their dog. Its a small world!
And now, the final word on tonnage!
Captain Michael Watson:
OK, heres the quick explanation of the various sorts of tons used when measuring and comparing ships. My reference materials were limited here but I did find a good etymology of how we came to use the specific measure of a ton that we do.
Apparently, a standard cargo that was shipped on European sailing vessels was a cask of wine that generally averaged around 2,200 pounds and took up roughly 60 cubic feet. These casks were called tuns and gradually acquired the spelling of ton in the mid-17th century.
Because the entire volume of a ship isnt available for carrying cargo, the measuring of the tonnage of a ship was further subdivided into gross and net tons. In broad terms, gross tonnage includes all cargo-carrying spaces along with other spaces included for passengers, crew, mess facilities, and engineering spaces. Net tonnage excludes those spaces not available for revenue. Simply put, that would be strictly cargo holds.
As an example, the Palmer measures 6,174 gross tons and 1,852 net tons. Because were classified as a research ship, Im not entirely sure if the net tonnage figure includes lab spaces or just the cargo hold. The gross tonnage figure, however, is a fair measure of the usable internal volume of the ship.
To further complicate the matter, there are two other tonnage figures in use for other types of vessels: deadweight tonnage and displacement. Simply put, deadweight tonnage is literally the weight of cargo carried by a vessel, in this case normally a tanker, and displacement tonnage is the actual weight of the ship itself. This figure is used primarily in comparing warships where theres no great amount of cargo being carried and it's a useful measure of the size of a warship.
I should also mention that when youre determining the stability of a loaded vessel, her actual displacement is one of the numbers you need for the calculations. In the Palmers case, an average trip with a full load of fuel, stores, and science gear would have us around the 7,000-ton mark, give or take a couple hundred tons. Thats the actual weight of the water the ship would displace and thus the weight of the ship itself.
So thats about it. Just remember that when youre comparing ships that you check the type of tonnage being quotedan 85,000-ton aircraft carrier is not necessarily smaller than a 90,000-ton cruise shipand dont forget that our European friends along with most of the rest of the world also throw in metric tons as a measure of cargo weight. It's barely 1 percent different from a good old-fashioned English long ton of 2,240 lbs and can be used almost interchangeably.
P.S. For the purists out there, my etymology reference for this was the textbook Introduction to Naval Architecture by Thomas Gillmer and Bruce Johnson. For anyone interested, this is a fairly heavy engineering text for basic naval architecture. Another book for someone just interested in shipbuilding is Ship Design and Construction by Andrew Taggart, I believe. Thats the one we used as midshipmen for learning the basics.
[Note: nationalgeographic.com does not research or copyedit dispatches.]
Back to top