As far as the bunching or clumping goes, Ferguson reminded: It's mostly about the weather. "Unless another storm hits, you see them naturally begin to separate," she said, describing each departing boat getting a head start on the next one yet to load. "It's when you have weather that has them sheltering they all tend to bunch into clumps." New generation.
We always called it convoying in the winter. Another factor is caused by ice in the rivers and lakes. Frozen taconite/loading equipment at the loading docks always causes longer loading times in the winter. Then as the stone docks start closing for the winter, the ships chase the cargoes and switch over to taconite. It’s just not winter storms that cause vessels to wait together in flocks like birds.