Peter Wiebe, Cabell Davis, and Bob Beardsley on the 05 deck of the Palmer gesture toward the dock at Punta Arenas, Chile. Photo Gallery >> Photograph by Mark Christmas

Temperature: 1.7° C (35° F)

Wind Chill: -8.1° C (17° F)

VIDEO

• Final discussion with the team

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Dockside, Punta Arenas, Chile.

I took one last shipboard look at the Southern Cross as we approached land. With the full moon lighting the waves below, the horizon was visible all around. It seemed that it was as light out as some of the days we spent in the southern latitudes.

The Drake Passage was very smooth. The Straits of Le Maire were a welcome sight. The transit through the Strait of Magellan was fast. The current and winds were following, and at times the ship was making over 20 knots.

The dock seemed to appear all too quickly. I stood on the rail with others in the midafternoon sun and watched as the mooring lines were secured and the gangway was hoisted into place. I thought I would have the urge to immediately run down the gangway and plant my feet on solid ground. But I didn’t. I didn’t leave the ship until later in the evening. Perhaps I wasn’t prepared for the finality of setting foot on the dock. It took a while to settle in—the cruise is over.

But the end of this cruise is really a beginning. It is the first of four cruises over the next two years that will complete the Southern Ocean GLOBEC investigation of the overwintering behavior and distribution of krill. I know that may sound a bit uninteresting. However, if you’ve looked through the dispatches, you’ll hopefully get a better picture of just how exciting this study is.

This is my last dispatch from the Nathaniel B. Palmer. I’ll file next from my office at National Geographic Society Headquarters in Washington, D.C. We’ll continue to answer e-mail questions until the end of June.

What a wild ride it’s been.

Q: Is it true that some South American nations are claiming part of Antarctica to be used for mining and sources of oil? If so, would the wildlife on land and marine life be affected? —Mira

A: Eileen Hofmann answers this one.

Yes, the South American nations of Chile and Argentina claim portions of Antarctica as part of their country. These claims go back many years, and maps of these countries do show the borders extending to and including parts of Antarctica.

The claims are in case it does become acceptable to exploit minerals or other natural resources in the Antarctic. At present, such activities are banned by the Antarctic Treaty, and so far all nations have abided by these regulations.

So, the terrestrial and marine life are not now threatened by activities such as mining or oil exploration. However, some commercial harvesting of fisheries is ongoing in the Antarctic. These activities are regulated by the Commission for Conservation of Antarctic Marine Living Resources, and this body tries to ensure that fishing activities do not harm animals such as penguins, seals, and whales.

Thank you for your question and for your interest in our cruise.

Thanks again to Eileen Hofmann for answering this one!

Have a question for Mark or the SeaLab team about the expedition or life at sea in Antarctica? In every dispatch, Mark will answer selected questions from readers.

[Note: nationalgeographic.com does not research or copyedit dispatches.]

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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 one’s 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 Father’s 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, it’s 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.

Endnotes:

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. It’s a small world!

And now, the final word on tonnage!

Captain Michael Watson:

OK, here’s 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 isn’t 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 we’re classified as a research ship, I’m 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 there’s 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 you’re determining the stability of a loaded vessel, her actual displacement is one of the numbers you need for the calculations. In the Palmer’s 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. That’s the actual weight of the water the ship would displace and thus the weight of the ship itself.

So that’s about it. Just remember that when you’re comparing ships that you check the type of tonnage being quoted—an 85,000-ton aircraft carrier is not necessarily smaller than a 90,000-ton cruise ship—and don’t 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. That’s the one we used as midshipmen for learning the basics.

[Note: nationalgeographic.com does not research or copyedit dispatches.]

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