Chunks of ice are nothing new this time of year in Boston Harbor, but the vast stretches of frozen seawater evident this winter are unlike anything local mariners can remember.
So much of the vital waterways into the area has frozen that commerce has slowed, passenger ferries have been canceled, the hull of a Coast Guard tender was pierced, and critical buoys indicating dangerous shoals and bends have become unmoored.
“This winter has definitely been one of the worst,” said Petty Officer Ross Ruddell, a spokesman for the Coast Guard in Boston. “We’re definitely approaching records for the amount of ice formed and broken.”
The Coast Guard has deployed two of its ships to break ice in the harbor, a Sisyphean task that since December has required repeated trips from the inner harbor in Boston to Hull Bay.
The work has been so demanding that this week, the Coast Guard cutter Pendant cracked its hull on the ice. Divers had to install a concrete patch on the bottom of the ship; it was back in service before the end of the day.
“This reflects what can happen to a boat that isn’t made to run into things,” Ruddell said. “When you hit hard, thick, sharp ice, it can put you in a dangerous position.”
Boston Harbor has much less traffic in the winter, but harbor pilots and docking masters coordinating tugboats remain at work at all hours of the day, as container ships and tankers ferry oil and natural gas.
George Lee, general manager of Boston Towing & Transportation Co., which operates seven tugs in the harbor, said he could not remember a previous winter that has made it so challenging to navigate the harbor.
Ice blocking narrow channels into ports in Braintree and Quincy has posed some of the biggest problems, especially as important navigation buoys have frozen over and sunken to a point where they cannot be picked up by a ship’s radar or have become unmoored by large floes.
The ice grew so thick this week that tugs and barges were frozen near a Citgo terminal in Braintree. The obstruction meant at least one oil tanker, the Green Sea, had to anchor several miles east of Nahant for three days as it waited for either nature or the Coast Guard to clear a passage.
“We have to be very careful with our equipment,” Lee said. “When you go into ice, there’s a tremendous chance to do damage that can cost a lot of money.”
Andy Hammond, executive director of the Boston Harbor Pilot Association, which employs nine specially trained pilots to guide large ships in and out of the harbor, said the combination of high winds, heavy seas, and encroaching ice has forced more jobs to be delayed this winter than he can remember ever happening.
Large amounts of ice in Chelsea Creek and the Little Mystic Channel have also occasionally blocked the primary source of fuel for their two pilot boats.
“I’ve never seen the ice this heavy or constant,” Hammond said. “It means we have to be on constant alert for danger.”
The extent of ice has also compounded the region’s transportation woes.
The ferry connecting Boston to Hingham has been canceled since Monday, while ferry service to Hull was restored for peak commuting hours Wednesday after being shut down earlier in the week.
Seawater, unlike freshwater, does not easily freeze because its high salt content and heavy wave action make it harder for ice to form.
Centuries ago, before shipping channels were deepened, a shallower Boston Harbor tended to freeze over more regularly. Old clips from The Boston Globe cited horses, pedestrians, and skaters on the harbor’s frozen surface.
While much of the harbor remains passable, large parts of Dorchester Bay and Hull Bay are completely covered in ice, while large floes can be found as far out as Graves Island Light Station.
On Thursday morning, Bob McCabe had just finished guiding an oil tanker out of Boston Harbor when he descended 90 feet down a snow-covered gangway toward a pilot boat cruising beside the massive ship.
Just as McCabe was about to shimmy down a sodden rope ladder, a colleague steering the smaller vessel noticed a problem heading straight for them: a large ice floe bobbing in the frigid water.
“He’s trying to Titanic us!” joked Joe Maloney, captain of the pilot boat.
Before leaving their port, Maloney had pointed to the significant sheets of ice where their boats are moored in East Boston.
“I haven’t seen it like that before,” he said.
At sea, as they passed floes in the inner harbor, he pointed to listing buoys weighed down by ice as he followed closely behind a 600-foot tanker sailing out of the harbor, allowing the ship to serve as an ice breaker.
When McCabe climbed aboard the pilot boat, wearing rubber gloves and a special jacket that inflates on contact with the water, he said his biggest concern is slipping on an icy deck. He took an unexpected plunge into the water in May and said he was lucky a boat didn’t crush him.
“It can be treacherous working in these conditions,” he said.
Scott MacNeil, a pilot who had guided out to sea another oil tanker, called trying to navigate in channels with damaged buoys and hard-to-see ice a nightmare.
On the way back to East Boston, after plying the ice-covered waters off Hull, Shawn Kelly steered the pilot boat past more floes than he could count.
He said he has damaged propellers on the ice, and as recently as a few days before an engine overheated after getting clogged with slush. He had to put the engine in reverse to clear it out and cool it down with seawater.
“This is the worst I’ve ever seen it,” he said. “It keeps you alert.”