Standing in the wheelhouse of the tug Andrew McAllister as it approached Portland Harbor on Friday, Capt. Bob Rand steered around Spring Point and ran into a pack of ice.

“It’s like we’re entering the Northwest Passage,” said Rand, referring to the Arctic sea route.

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The ice stretches across the Fore River and into Casco Bay past Bug Light in South Portland. People who work on the Portland waterfront say the harbor hasn’t frozen up like this in 35 years.

The heavy tugs, ships, ferries and barges that work in Maine’s largest port have been hampered by the ice but are still able to operate. Smaller boats, on the other hand, have had to stay at the pier. The ice, which rises and falls with the tide, has also caused damage at some marinas.

A glancing blow against a large piece of ice could affect the steering of even large cargo and tanker vessels inside the harbor.

The Coast Guard cutter Shackle has been breaking up ice every day for the past week so ships can make their deliveries.

The 65-foot vessel, which has a reinforced steel hull at its bow, cleared a path last week for the Long Island fire boat so it could dock in Portland before last weekend’s storm. On Tuesday, the cutter smashed the ice around the Wyman power plant on Cousins Island so barges carrying oil could make a delivery. Also Tuesday, the cutter broke ice for the Islander, the ferry that runs between Cousins Island and Chebeague Island.

The crew of the Islander in recent days has been crossing between the two islands every few hours through the night to keep the ice on its route from re-freezing before morning, said Kevin Wentworth, one of the ferry’s captains. The first ferry leaves at 6:40 a.m.

“We are just trying to make sure we can leave,” he said.

The ferries used by Casco Bay Lines are large enough to handle the frozen buildup. Between some of their regular runs, the ferry captains have used their vessels to break up ice for smaller boats in the harbor, said Nick Mavodones, the operations manager.

Portland Pilots, a company that provides harbor pilots for ships, has stopped using its newer aluminum boat in favor of a steel boat built in the 1960s. Despite the steel hull, Capt. Steve Jordan said, it took an hour Monday to push through the ice from the boat’s berth at Union Wharf to the Maine State Pier about a quarter mile away.

DAMAGE FROM RISING TIDES

There are eight mooring pilings that hold DiMillo’s Floating Restaurant in place. The top 5 feet of the pilings are so caked in ice that the chains connecting the pilings to the restaurant are getting hung up when the tide rises, creating an alarming cracking sound, said Steve DiMillo, one of the owners. He worries the pilings could be pulled out of the harbor bottom.

Strong north winds have been pushing the ice from the Portland side to the South Portland side of the harbor. At South Port Marine in South Portland, ice on pilings is preventing the marina’s floating docks from rising and falling with the tides. About 10 percent of the marina’s pilings have been damaged beyond repair, and five docks have snapped, according to Lisa Fortier, the marina’s controller.

After the Coast Guard cutter breaks up the ice, it reforms again overnight, said Mark Usinger, who runs A.L. Griffin Ship Chandlers, which uses a 40-foot fiberglass boat to make deliveries to ships.

He said his boat has been stuck in ice since last Thursday at its berth at South Portland’s Turner’s Island. His landlord is now using an air compressor to pump air under the ice in an attempt to break it up with air bubbles.

Usinger said ships are arriving in the harbor encased in ice. The crews are using steam from the engines to melt ice on railings and mallets and steam to clear the deck. He said crew members – many from tropical climates – look cold and exhausted.

“It’s been a brutal winter for everybody, whether you live here or visit here by ship,” he said.

‘IT’S CERTAINLY CHALLENGING’

Portland is normally an ice-free port because the Gulf of Maine has strong tides. The tides mix the water column and bring deeper, warmer water to the surface along the coast, said Huijie Xue, a physical oceanographer at the University of Maine. And because the Fore River is a tidal river, it carries little fresh water into the harbor during the winter, making the salt content in harbor water similar to that in the ocean. Fresh water freezes at 32 degrees Fahrenheit, but seawater freezes at about 28.4 degrees.

However, heavy snowfalls in recent weeks have introduced more fresh water into the harbor, making it more likely to freeze, said Brian Fournier, president of Portland Tugboat LLC, which operates four tugboats in the harbor.

When snow falls after ice has formed, it melts on top of the ice and then freezes overnight, just like an ice dam on a roof, he said.

Ships continue to make deliveries, he said. “But it’s certainly challenging. Ships come to a complete stop in ice like this.”

Extremely cold temperatures have also contributed to the ice buildup, James Brown, a meteorologist with the National Weather Service in Gray.

Brown said there has not been one day in February when the temperatures have been above normal. On Feb. 14, the normal high is 34 degrees and lows average 16. This year the high was 16 and the low was 8 below zero.

The harbor’s fishing fleet has suffered the most. The ice has trapped some boats at their berths. A much bigger blow, though, has been the series of storms that have swept through the region in recent weeks, keeping fishing boats in port. The volume of fish landed at Portland Fish Exchange from Jan. 15 to Feb. 16 was down 54 percent from the same period last year.

Charles Adams, captain of the groundfish dragger American Heritage, said he has only fished four days in the past five weeks. As a result, he has fallen behind in a lot of bills.

“It’s been horrible,” he said.