MANILA, Philippines – A U.S. Navy minesweeper was stuck on a coral reef in the Philippines for a second day Friday, as the crew struggled to extract the ship and Philippine authorities tried to evaluate damage to a protected marine park.

The Navy’s 7th Fleet said in a statement that the crew of the USS Guardian was working to find out the best method of safely extracting the ship. Winds and waves were stronger Friday and may make it more difficult to free the ship.

It had just completed a port call in Subic Bay, a former American naval base west of the Philippine capital, when it hit the reef Thursday.

The ship was not listing or leaking oil but its bow struck the reef, said Angelique Songco, head of the government’s Protected Area Management Board

She said it was unclear how much of the reef was damaged. She said the government imposes a fine of about $300 per square yard of damaged coral.

In 2005, the environmental group Greenpeace was fined almost $7,000 after its flagship struck a reef in the same area.