March 10, 2012
Western Pacific Ocean, north of Papua New Guinea
For all the right reasons, we spent 17 days on the Solomon Sea concerned about deep-sea forces like cold, corrosion, temperature, and pressure and how they affect the performance of the DEEPSEA CHALLENGER. But it took our minds away from the risks we face on the surface: waves pushed by winds that make them higher until they collapse under their own weight, swells produced by distant storms that force a 2,000-ton ship to swing like a pendulum.
This morning the Mermaid Sapphire was two degrees south of the Equator and steaming north toward Guam at 11 knots. The moderate waves pushing us from the south had been replaced by large swells pressing in from the east. The island-protected Bismarck Sea was behind us; we were moving across the open reaches of the Pacific Ocean.
The mother of all oceans covers about 58 million square miles (150 million square kilometers) and is wide enough to swallow all the world’s continents. She is the wildest, deepest, and most biologically diverse mass of water in the solar system. Within her boundaries are more islands, coral reefs, undersea mountains, and deep trenches than any other ocean. The stupendous amount of oxygen and carbon dioxide she produces and absorbs helps shape the chemistry of the Earth.
The great blue heart of the planet is always moody and often malevolent. From the Arctic to the Antarctic, from Asia to the Americas, her great reach of water produces powerful winds and waves. She has the meteorological energy to generate every conceivable kind of weather, from waterspouts to warm fronts to Category 5 typhoons.
“The height of sea waves depends on wind strength, distance of open water, and how long the wind has been blowing,” said Captain Stu Buckle. We were standing on the bridge deck of the Mermaid Sapphire looking at the big swells rolling under his ship. He was telling me about the sea conditions we might find over the Mariana Trench. “Swells are different than waves. They’re the regular undulating motion caused by faraway storms. They can travel thousands of miles from where they’re formed.”
This time of year the waters over the Mariana Trench usually have several days of seven- to ten-foot (two- to three-meter) swells followed by a week of 13- to 20-foot (four- to six-meter) swells. This is going to make it hard to get the DEEPSEA CHALLENGER into and out of the ocean. During our dives in the Solomon Sea, the highest swells we saw were seven feet (two meters). Even so, we struggled to get the sub safely back on the ship.
“The weight of the sub is carried on the end of the knuckle boom,” said the captain. “Because the end of the boom and the lift wire below are far from the center of gravity of the ship, they move further and faster. If the tag lines can’t handle the strain, the sub will buck like a bronco.”
Big ocean swells can come from two and sometimes three directions. Far too frequently, two swells join forces under the ship and amplify the roll. Those are the moments when people fall down stairwells, computer screens shudder, and the safest place on the ship is flat on your back in your bunk.
The mother of all oceans is bereft of sentiment or memory. She doesn’t care about the color of our ship or the success of our last dive. She will be hunting for the weak spot in our competence, commitment, and courage.
Photograph by Joe MacInnis