Lock and Dam Procedures, and Where They Go Wrong

A lock transit looks slow and calm from the shore. A tow eases into the chamber, the gates close, the water rises or falls, the gates open, and the tow moves on. From the deck, it is one of the more hazardous routines in towing: heavy barges in a tight concrete box, lines under changing loads, and currents at the approaches that can push a tow where the pilot does not want it.

Who controls what

Most locks on the inland system are operated by the U.S. Army Corps of Engineers. The lock operator controls the gates, the chamber, and the order of traffic, and gives the vessel instructions by radio and signal. Federal regulations for navigation locks (in 33 CFR Part 207 for many waterways) set rules for approach, mooring, and conduct in the chamber.

The vessel controls its own approach, its speed, its position in the chamber, and its line handling. When something goes wrong, the question is often which side of that line the failure fell on.

The approach

Current near a dam can be strong and uneven, especially in high water or when spillway gates are open. Outdraft can pull a tow toward the dam. A pilot lining up on a lock has to account for current, wind, the size and draft of the tow, and the horsepower available. Allisions with lock walls, guide walls, and dam structures often start a quarter mile out.

Inside the chamber

Once in the chamber, the tow is secured with lines to fixed or floating mooring points on the lock wall. As the water level changes, deckhands tend the lines so they do not part or jam. Larger tows that do not fit in one chamber are split into cuts and locked through in pieces, which adds handling, more lines, and more time on wet barge decks.

Where people get hurt

• Lines parting or snapping back under load
• Hands caught between lines and bits
• Falls on wet barge decks or between barges during a split
• Deckhands crushed between a barge and the lock wall
• Falls into the chamber

Where vessels get hurt

• Allisions with guide walls and lock gates on approach
• Barges breaking free during a double lockage
• Tows set onto the dam by outdraft

Records that fix the timeline

The lock operator's records are often more precise than the boat's own log. Ask early for:

• Corps lock logs and lockage records
• Radio recordings between the lock and the vessel, if kept
• The vessel's log, AIS track, and any engine data
• River stage and spillway gate settings for the day
• The company's lock transit procedures and the deckhands' training
• Photos of the lines and mooring points involved

The practical standard

A prudent operator plans the approach for the conditions that day, has enough power for the tow in that current, briefs the deck crew on line handling, puts experienced hands on the lines, and follows the lockmaster's instructions. When lockages go wrong, it is usually because one of those steps was rushed.

About the author

Captain Mitchell S. Stoller is a Master Mariner Unlimited, former Exxon tanker master, and former Los Angeles Harbor pilot. About Captain Stoller