As the skipper of Galileo 3, a 30-foot sailboat on the Columbia River, I tell my crew that I am comfortable with 15 feet of water under the keel, get nervous when it drops below 10 feet, and take immediate action if it drops below 6 feet. That’s because I cannot constantly monitor my chart to avoid running aground. So, I was amazed to find out that the huge cargo ships that navigate the river for 100 miles from its mouth at Astoria to the Port of Portland sometimes have as little as two feet of vertical clearance.
This feat of navigation is made possible by the knowledge, skills, experience, and electronic equipment possessed by three sets of marine professionals who cooperate tightly: the river pilots who steer the ships, the hydrographers who survey the river, and the dredge operators who maintain the required depth of the navigation channel.
Maintaining a consistent minimum depth is essential to safe navigation. However, due to the very dynamic nature of the river’s bottom, keeping it navigable requires an endless cycle of surveying and dredging—a Sisyphean task costing more than $50 million a year.