It’s all in a day’s work…on the water - Soundings Online

It’s all in a day’s work…on the water

Author:
Publish date:

To get to work, Julie Oberg, Peter Lewit and NOAA Ensign Matthew Jaskoski strap on motorcycle helmets and board a 29-foot powerboat dangling from two massive davits 20 feet above the ocean at the side of the Thomas Jefferson, a 208-foot hydrographic ship.

To get to work, Julie Oberg, Peter Lewit and NOAA Ensign Matthew Jaskoski strap on motorcycle helmets and board a 29-foot powerboat dangling from two massive davits 20 feet above the ocean at the side of the Thomas Jefferson, a 208-foot hydrographic ship.

Read the other stories in this package: Scanning the depths   Keep your own charts current

The powerboat — whose only name is a number, 1005 — has been riding on a cradle on the starboard side, while its twin, No. 1014, sits idly on a cradle on the port side. With a command from a deck officer, the davit winches begin spooling off cable, and Oberg, Lewit and Jaskoski ride 1005 down to where slate-gray swells at first wash their unpainted, welded-aluminum vessel, and then buoy it. With luck, the helmets haven’t been called into play. Oberg fires the diesel, and the davit cables release from 1005’s lifting rings.

As Oberg steers away from the ship, another day of hydrographic survey has begun. It is around daybreak. If the seas remain moderate, 1005 will cruise near its mother ship until just before sunset. There are so many outdated charts and so little time.

For however many hours lie before them, the crew of 1005 will steer the launch along a series of parallel courses determined by a technician and entered into a computer’s memory. As they travel at about 8 knots, the team monitors sonar equipment that will record depth soundings and indicate unusual seabed objects.

Lewit spends most of his day below, monitoring a bank of four video screens. He is a senior survey technician, a government-employed scientist. His job on board is to assure that 1005 follows the parallel courses that appear on one of his video screens, overlaying an electronic chart. Lewit, who is 51, owns a home in Cornwall, N.Y., but for weeks at a time lives in a stateroom aboard the Thomas Jefferson. On days like this, when seas are accommodating, he takes a seat at the center of what is 1005’s main cabin, surrounded by a U-shaped counter, his video screens forward at the base of the U. By voice, he keeps Oberg informed of when she needs to turn onto a new course.

Oberg, who is 35 and a Florida native, also is a government employee, a seaman surveyor or coxswain. She drives 1005. A gauge on the video screen mounted at the helm shows whether she is to port or starboard of the assigned course. The screen also shows her the same chart Lewit is following below. Oberg hand steers the slow-moving boat, her wheel in constant motion as she deals with a quartering sea that wants to push 1005 off course. When she needs help handling the launch, she speaks to Jaskoski.

In 2004 Jaskoski, who is 26 and from Kingsport, Tenn., completed his master’s degree in oceanography in New Zealand, then joined the NOAA Commissioned Corps as an ensign. He spent three months in officer training at the U.S. Merchant Marine Academy in Kingsport, N.Y., then was assigned to the Thomas Jefferson, where he is accumulating 150 days of sea time and completing a workbook that will earn him seaman credentials. As a junior officer he is qualified to do Oberg’s job and some of Lewit’s work. He will spend another year at sea before being assigned to shore duty for a few years.

From his command seat, Lewit calls out to Oberg that 1005 has finished scanning the bottom along one course. He gives her directions for the next pass, and she steers onto the appropriate course. Before joining NOAA four years ago, she crewed aboard yachts, traveling around the world. Steering 1005 is nothing new for Oberg, but it is not her only assignment. On board the Thomas Jefferson, she is a member of the deck crew, working for a chief who came to NOAA from a Navy career. They swab decks, maintain the vessel and participate in all of the emergency drills the ship’s crew is required to perform.

On 1005 the days consist of cruising back and forth, sweeping the bottom with the fan-like rays of the multibeam sonar. On this day, the work is in an anchorage just off the entrance to Chesapeake Bay. A dozen large cargo and tanker ships are anchored here, some empty and riding high, others settled low into the water. At times, the bottom of one of these ships will be within a foot of the channel bottom. This adds to the urgency of what for Oberg, Lewit and Jaskoski could be a monotonous job. They know that their scanning could have missed a small but potentially hazardous object poking up from the bottom, capable of ripping open a ship’s steel hull.

The Thomas Jefferson is conducting its own multibeam survey while 1005 is in the water. Commanded by Cdr. Emily Christman, the ship carries a second device that can improve the chances of finding those small, undetected hazards. Near the fantail, a torpedo-shaped object rests on deck. This is the side-scanning sonar, a machine that costs hundreds of thousands of dollars. The crew refers to it as the “fish.” At the end of a steel tow line, the fish is dragged behind the Thomas Jefferson and sends out horizontal beams that return shadowy pictures of the water column, revealing, for example, the spindly mast of a sunken ship rising toward the surface.

Among the scientific crew working aboard the Thomas Jefferson is 28-year-old Erin Campbell of Wilmington, N.C. A geographer by training, her job aboard the ship is to plan future surveys. Campbell — who recently was reassigned to the NOAA ship Rainier — does this by displaying a nautical chart of the proposed survey site on her computer and superimposing the lattice of courses called a “line plan.” Part of the design of these plans is intuition. She doesn’t want to send the ship or its launches too close to shore, where they could encounter uncharted hazards. So she designs plans with courses offshore but roughly parallel to the coast. Each line in the plan has a number, a street name of sorts. For the launch that receives this plan, the work will be “kind of like mowing the lawn,” Campbell says. “You go back and forth and want to make sure you cover the whole thing.”

If in the course of a survey an unusual object is discovered protruding from the bottom, a team of divers will be sent to investigate. Jaskoski is one of five divers aboard the Thomas Jefferson. The divers carry with them a pressure gauge, and when they find the object, they will take the gauge to its highest point and get a reading. That translates on a chart into the least depth available in that location for a passing vessel.

Whether it is the Thomas Jefferson or one of the launches that is conducting a survey, crews must stop periodically and lower a conductivity temperature and depth device overboard. A cable attached to the device relays information to the on-board computer, providing information that determines the speed of sound in that particular water. The speed of sound varies according to water temperature and salinity, and since sonar uses sound waves to measure depth, those measurements have to be adjusted according to current conditions.

Current charts may, in many cases, be “grossly out of date,” as Christman puts it, but some time in the future those who use charts will benefit from NOAA’s precision on the water today.