Citing the dangers of floating ice, the U.S. Coast Guard issued broader restrictions Sunday on Delaware River traffic, now requiring steel hulls on any vessels traveling the river from the Tacony-Palmyra Bridge south to below below Wilmington.

With daytime and nighttime air temperatures projected to remain well below freezing for the rest of the week, the new restrictions extend the steel-hull requirement about 45 additional miles southward on the Delaware.

"There have been reports of ice formation that may affect navigation," said a marine bulletin issued by Coast Guard Captain Kathleen Moore, sector commander for the Delaware Bay.

The Coast Guard initially imposed steel-hull requirements last week on vessels operating above the Tacony-Palmyra Bridge, as well as on the Schuylkill, the Salem River in South Jersey and the length of the Chesapeake & Delaware Canal. That body of water runs east to west from Chesapeake City, connecting the Delaware with the upper Chesapeake Bay.

Coast Guard Lt. Veronica Smith, chief of waterways management for the Philadelphia station, said there was no immediate threat to commercial shipping.

But most recreational boats are built from fiberglass or wood, effectively barring them from the water pending warmer temperatures.

Since early January, the Coast Guard has been using its two 65-foot tugboats, Cleat and Capstan, to break up ice, which poses a flooding threat when it blocks local streams.