EASTPORT, Maine — Back and forth, in and out of little coves and across the bays, the 32-foot Sea Ark has been passing through Cobscook Bay this week, mapping the bay bottom.
The three crew members from the National Oceanic and Atmospheric Administration keep their eyes glued to computer screens inside the boat, where colored lines represent the 254 sound beams being shot to the bottom.
Computer-generated views of the bottom are so clear that sand waves and even small rocks are visible.
But it is when the distinct shape of the hull of a sunken fishing boat appears on the computer screen that the team is jolted from its focus on the technology. It turns out that this particular wreck already has been charted long ago, but coming across it serves to remind the men of the human reason they are in Maine: 16 fishermen lost at sea in the past five years.
“I sometimes get caught up in the details,” team leader Nick Forfinski of Washington state said Monday as he scanned the computers. “But the community response here reminds me why we are here.”
“We can feel it,” Cmdr. Lawrence Krepp said. “In 18 years of doing this, I’ve never felt anything like it.”
NOAA is mapping the bottom of the Bay of Fundy and Cobscook Bay, which hasn’t been done since the late 1800s, because of the many local fishermen lost in these waters.
Fishing communities throughout the Bay of Fundy have lost more than a dozen men in a series of vessel sinkings in recent years. Since December 2008 there have been seven fishing-related deaths in Cobscook Bay alone.
That loss of life was what caused the NOAA crew to drop its plans to map the harbor at Newport, R.I., and instead spend this summer and fall in Maine.
Urged on by local pilot Capt. Robert Peacock, who is also an Eastport city councilor, U.S. Sens. Olympia Snowe and Susan Collins of Maine asked NOAA for the full bottom survey.
Cobscook Bay has not been officially mapped since 1899, and Krepp said Monday he was astounded at the accuracy of those early charts, created with the use of lead drop-lines. “I have to credit our forefathers,” he said. “The perimeter mapping of the bay is amazing.”
But today’s technology is quite different and local fishermen who drag the bay for urchins and scallops are hoping that uncharted obstructions will be located so they can avoid snagging their gear and flipping their boats.
In the middle of the bay Monday afternoon, accompanied by seabirds, a single whale and light drizzle, team member Matt Andring of Tennessee cast a Digibar — a ground velocity sensor — overboard. It takes into consideration the water temperature and salinity, and determines the speed that the sonar beams travel through the water. That speed is then converted by the computers on board to map the depth, contours and obstructions.
The sound is shot at seven pings a second, at a decibel too high for humans to hear. The longer the sound takes to return to the boat, the deeper the water.
“It’s like mowing grass,” Krepp said. “We go back and forth, overlapping the same spot, so we don’t miss a spot.”
One of the computers shows the beams and what they are striking. The image on the screen looks like a teal-colored fan — narrow at the top where the boat is located, and wider at the bottom where the sound is striking the floor of the bay.
All the information gathered by the onboard computers is taken to the NOAA team’s land headquarters in Eastport and translated into up-to-date charts.
Krepp said there haven’t been any surprises on the bottom so far. Wrecks have been discovered but they were previously reported and noted on the charts.
“The only other place you will find some of this type of terrain is Alaska,” he said, referring to steep underwater cliffs.
“But we’re also surprised at some of the large, flat areas we are seeing,” Forfinski said.
The aggressive currents and tides in Cobscook Bay weren’t a surprise but the crew acknowledged that they were amazing.
“We were well-warned,” Krepp said. “You don’t find this type of current and tides in other places.”
The crew members said that before coming to Maine they were stationed out of Woods Hole, Mass., where the tides ranged 2 feet. In Cobscook Bay, the difference between low and high tide can be up to 24 feet. That’s an extraordinary amount of water churning and being displaced twice a day.
“The water in this bay is fast and furious,” Krepp said.
Local experts, including David Dent from the Department of Marine Resources, rode with the crew members as they performed “a reconnaissance drive” of the bay last week. Krepp said local fishermen and others have been extremely helpful in providing information to the NOAA crew.
Krepp said the team in Maine is one of six similar teams deployed around the country.
“We are just one piece of NOAA’s hydrographic picture,” Krepp said. But he said the charts being created for the Bay of Fundy are some of the few charts NOAA has created that are in meters, rather than fathoms or feet. That is a nod to the Canadian fishermen who will also use the charts, he said.
The team expects to be mapping the bay until late October and will return next spring if the job is not completed.