SYDNEY, N.S. -- A tanker remains grounded on the sandy bottom of a Cape Breton bay, as a salvage company readies a more powerful tug after a failed attempt to dislodge the boat Tuesday night.

The bid to refloat and tow the Arca 1 resulted in only minor movements towards deeper water, Olous Boag, vice president of McKeil Marine, said Wednesday.

Boag said the tow was called off shortly after high tide, and it was determined the larger tug Tim McKeil would be required.

He said in an interview the company had hoped that by pumping out the 300 tonnes of ballast water from the tanker, it would have permitted a smaller tug to pull the vessel off the sand north of Sydney Mines, N.S.

However, difficulties breaking through a half metre of ice to install portable pumps to remove ballast water caused slowdowns -- and it turned out additional portable pumps will be needed to fully empty the tanks between low and high tides.

Only about half of the ballast water was pumped off in the first attempt.

"It turns out we need the larger horsepower and additional pumps," said Boag.

The salvage executive says the firm remains optimistic the tanker can be moved in a few days, but it will require bringing in additional steel wire and floating rope because the more powerful tug must stay about a kilometre away from the grounded vessel.

Boag said the vessel is sitting in just 60 centimetres of water. "At low water, you can almost walk around the Arca," he said.

There will be "challenges" in setting up the next towing effort, he said, including worsening weather and the freezing of ballast water.

Tests will also be needed to ensure the force of the tow doesn't rip off the connection points to the tanker, he added.

The precise timing of the next attempt to move the ship will depend on daily forecasts and wind speeds, and the Canadian Coast Guard must approve the plan, said Boag.

The Arca 1 -- which is carrying 15 tonnes of fuel for its own engines -- ran aground just north of Sydney Mines on Sunday after losing engine power, and its six-member crew was rescued later that day.

The tanker was en route to Mexico carrying no cargo when it experienced mechanical difficulties.

-- Story by Michael Tutton in Halifax.