The Merrimack River is a playground for thousands of people at this time of year, but its well-earned reputation should always cast a sobering shadow over it.
Two boats and a kayak navigating at the mouth of the river found themselves in danger over the weekend. The larger of the boats — a 23-footer — sank. Luckily, thanks to fast reactions by nearby boaters, no one was lost. But the incidents serve as a reminder to boaters that even in the summer, the river mouth can be extremely hazardous.
The Merrimack is one of the largest rivers in New England, and on a daily basis millions of gallons of water rush through its relatively constricted mouth. The result is a funneling effect that can produce waves in the river of unexpected size, and currents with unexpected ferocity. Even for experienced boaters, a trip through the Merrimack’s mouth can be a white-knuckle, hair-raising experience.
There’s a perfect storm of conditions that can create life-threatening hazards, and those forces were in play this past weekend. The river mouth is often at its most dangerous when the outgoing tide and the river’s natural sea-going flow combine, creating an enormous current rushing to the sea. The water can run so fast it requires significant engine power for boats to push their way upstream. An engine breakdown in these conditions can send a boat helplessly out of control.
Then, there are the large standing waves caused by these currents and the sand bars that lie under the surface. The waves’ location and size changes as the tides and conditions dictate. A boater navigating along the river can go from relatively flat water to fast-flowing waves of 4 feet or more in the space of a few feet, leaving little reaction time. These are the kinds of conditions that can cause boats to capsize, if a boat is broadsided by such a wave.