Tugs rolling over is often fatal, although personally I would have thought they would be more bouyant. However, I guess if the watertight doors were open, too much gets aboard too rapidly.
At any rate, about 20 years ago, a fuel oil/gasoline hauling freighter on the Great Lakes lost main power. They requested a tug, which arrived and took her in tow. While underway heading into the area known as Grand Traverse Bay, near Traverse City, MI, the tug also lost power. Why she was headed into GT Bay I don't know, but back then there was an off-shore delivery point.
At any rate, the freighter of about 500' or so, the Wisconsin I believe, continued on due to her momentum and continued past the essentially stopped tug. The towing cable dropped under the tug, and due to the pull from the freighter, pulled the tug over 180 degrees causing her to sink rapidly with loss of all hands.
That part of the bay is about 500' feet deep and cold, so none of the hands were ever found. The saying is that some parts of the Great Lakes don't give up their dead. Case in point, is the 700+ Fitzgerald that went down N. of Whitefish Bay in Lake Superior. On the very last authorized dive on her wreck, cameras found a body about 100' forward of the bow. Since this was the first every body discovered (or allowed to be reported), an investigation ensued. It was determined that the body was from a tug that sunk in 1913!
Sorry, not a Hatt story...but did involve a boat!