PHOTOS: U.S. Freighter 'Roger Blough' Hard Aground in Lake Superior

The motor vessel Roger Blough sits grounded in the vicinity of Gros Cap Reef in Whitefish Bay, Lake Superior, May 27, 2016. U.S. Coast Guard Photo

A U.S.-flagged freighter that spent Memorial Day weekend hard aground in Lake Superior is still stuck Tuesday as salvage crews continue on plans to refloat the vessel.

The 833-foot MV Roger Blough ran aground Friday afternoon on Gros Cap Reef in Whitefish Bay in Lake Superior.

The Coast Guard said Tuesday that the threat of a fuel oil spill was minimal and flooding on the vessel remained stable. Boom has been deployed around the stern near the ship’s fuel tanks but strictly as a precautionary measure. No fuel is believed to have leaked since the grounding on Friday.

Over the weekend, response crews were busy taking exterior draft readings of the vessel as the crew of the Roger Blough continued interior soundings of the tanks to ensure flooding remained under control.

All crew members remain on board the vessel and are reported safe with no injuries.

The crew of Coast Guard Cutter Mobile Bay, homeported in Sturgeon Bay, Wisc., enforces a 500 yard safety zone alongside the motor vessel Roger Blough, May 29, 2016, near Gros Cap Reef in Whitefish Bay in Lake Superior. U.S. Coast Guard Photo

Representatives from the National Transportation Safety Board were expected to arrive Tuesday night to assist the Coast Guard in investigating the cause of the grounding.

A 500 yard safety zone has been put in place around the vessel.