cargo ships carrying supplies. the coast guard says 90% of the heating oil used in the northeast is transported by barge on the river. >> every night the i3 freezes on the hudson and the barges can get through. every day the coast guard has to go out to ensure the commerce flow of the hudson river doesn't stop. >> a fox news drone caught the penobscot bay and grew in action last week in kingston new york carving through frozen serve. they are capable of more. they icebreaking tugs are equipped with machines powered by huge engine that forced air under the surface to reduce friction on the ships hole, allowing them to ram through solid ice more than 27 inches thick. more effective than the 65 footers. have you hit ice that is too thick? >> not on this boat.