As U.S. Navy assets steam towards the Philippines to provide humanitarian assistance and disaster relief to the victims of Typhoon Haiyan, Navy hydrographers are busy charting safe passages through potential navigation hazards created by the receding storm surge.
USNS Bowditch (T-AGS 62), a Navy survey vessel, was one of the first ships on station and began immediately surveying the approaches to San Pedro Bay to ensure naval relief efforts are conducted safely, and Navy ships can get as close to land as possible.
“In many natural disaster situations around the world, forward-deployed Navy and Marine Corps assets act as first responders for U.S. relief efforts,” said Chris Kent, deputy operations officer for the Naval Meteorology and Oceanography Command. “Natural disasters can compromise navigation approaches, making it difficult, even dangerous, to access the harbors. Our job is to identify those hazards.”
Kent explained that the storm surge that devastated so much of Tacloban City and other areas around San Pedro Bay typically carry significant debris out into the bay as the surge waters recede. Additionally, powerful forces like this storm surge can shift ocean bottom sediment around, rendering existing navigation charts useless.
“We performed similar roles in the 2004 Banda Aceh tsunami and the 2010 earthquake that devastated Haiti,” Kent explained. “In both cases, Navy survey ships and aircraft went in first to chart the approaches.”
By a stroke of good fortune, Bowditch was already in Philippine waters conducting cooperative surveys and training with the Philippine navy when the typhoon hit. In fact, she had to sortie to avoid the storm. As the scope of the disaster quickly became apparent and the U.S. committed ships to the response efforts in support of the Philippine Government, the Bowditch crew was tasked to begin a survey from the 200 meter depth line in towards the shore.
As ships from the USS George Washington strike group closed in on Leyte Gulf to support relief efforts, the Bowditch searched for hazards that could damage high-value assets like the carrier. According to Kent, the shallow depths of San Pedro Bay will require many of the ships in the strike group to anchor well off-shore, accessing the land via helicopters and small boats.
In Okinawa, U. S. Marines are preparing to embark on two amphibious ships, USS Germantown (LSD-42) and USS Ashland (LSD-48), that will sail to Tacloban to provide on-ground assistance. With significantly shallower drafts, these ships will be able to get in much closer to the land, but they will be even more at risk to submerged debris.
Bowditch is operated by the Military Sealift Command for the Naval Oceanographic Office, a component of the Naval Meteorology and Oceanography Command headquartered at the Stennis Space Center in Mississippi.
Bowditch is one of six Pathfinder-class ships with an all civilian crew of professional mariners and scientific support personnel. With a 329 foot length and a 58 foot beam, the ship displaces 4,762 long tons.
In a recent interview with the Navy’s CHIPS magazine, Rear Adm. Brian Brown, commander of the Naval Meteorology and Oceanography Command, described the survey ship capabilities.
“These ships have modern full ocean depth multi-beam and single-beam sonar systems for accurately measuring bottom depths and features, towed side-scan sonar systems for acoustic imaging of bottom features and navigation hazards, ocean current profilers, sub-bottom profilers for measuring stratification of seabed sediments, and over-the-side devices that collect physical ocean parameters such as temperature and salinity with depth.”
Bowditch also carries two 34 foot long hydrographic survey launch for shallow water surveys. Complemented with wide-beam echo sounders and side-scan sonar, these boats will be essential for preparing the approach for the amphibious ships that will bring the Marines ashore.
“The Navy’s survey ships are a little-known but critical asset for the Navy,” said Rear Adm. Jonathan White, Oceanographer of the Navy and resource sponsor for the survey ships. “Their work contributes to the creation of accurate navigation charts in all the world’s oceans, and helps ensure safety of navigation. They have no home ports and are continuously deployed around the world, stopping only for necessary maintenance work. They are truly a national asset,” he added.
[mappress] Press Release, November 15, 2013; Image: US Navy