The biggest difference between coastal and river boating is the constantly changing nature of inland waterways. Depths, currents and channels change, and even navigational aids shift, creating problems for both commercial and recreational boaters.
On most rivers, the deepest water and strongest currents are on the outside of bends. If the river current is strong, stay to the inside of a bend or near the inside shore, but be aware that and shoals may form on the inside of turns.
River depths vary depending on the amount of water flowing downstream. Detailed river charts for Army Corps of Engineers-maintained waterways are indispensable for safe river boating.
River charts show depths differently from coastal charts, so check the chart title block to see how they’re indicated. You can also determine water depths by referring to daily river reports. Stay within marked channels unless you are certain the water depth is sufficient for your boat’s draft.
Look out for logs and other river debris. Like icebergs, the part you don’t see is often bigger than the part you see. If you hear or feel a thump or unusual vibration, stop and check for damage.
A river’s bank gives you a clue to water depth. You can expect relatively deep water up to the shoreline along a steep bank. A gently sloping beach running back a long way from the water’s edge usually means shallow water a long way from shore.
You can often identify shallow water by a difference in color, the presence of ripples when the water is calm or a patch of quiet water in the midst of choppy water.
If you suspect shallow water, slow down to bare steerageway. Engage the propeller only as needed. If possible, partially raise the prop on an outboard motor or stern drive. Check your wake to see if you’re stirring up mud or sand, and place a lookout at the bow to measure water depth with a boat hook or weighted line.
To learn more, take the USPS University seminar Boating on Rivers, Locks and Lakes. Find a seminar near you.