Understanding The "Rules of the Road" on Waterways

There are consequences when  interfering with a large ship in many of our narrow channels, especially in our busy port cities, such as New York City, Boston, Houston, Los Angeles and Seattle.

Every day, hundreds to thousands of ships larger than 65 feet in length, enter and depart our busy ports. These vessels include tankers, cruise ships, container ships and tug-barge combinations. All these vessels are constrained by their draft; and are unable to maneuver in the narrow range inside the narrow channels in and around our ports and harbors.

The “Rules of the Road”, the federal navigation rules provide for this event by giving these ships priority, or right-of-way, over smaller vessels when navigating in these narrow channels.

Many recreational boaters fail to realize the physics involved in stopping or maneuvering a large ship. The average recreational boat stops within a couple of boat lengths, even if they are traveling at maximum speed. However, it can take a large ship thousands of yards to stop.

An example would be if a water skier stopped 1,000 feet in front of a tug and barge. The skier would have less than one minute to get out of the way of the tug and barge, otherwise the skier would be run over.

The local boating public should be aware of the penalty provisions within U.S. Code, Title 33, Section 2072, that specify “Whoever operates a vessel in violation of the navigation rules is liable to a civil penalty of not more than $5,000 for each violation, for which penalty the vessel may be seized and the case shall be brought before the district court of the United States of any district within which the vessel may be found.”

Law of Gross Tonnage

The law, which is more common sense then explicitly written in the code, goes like this: “The heavier vessel always has the right-of-way.”

This is based on simple Newtonian physics. Newton’s first law talks about objects in motion stay in motion unless another force is acted upon it. In other words, if a boat is moving east at 5 mph and you were in the vacuum of space, it would never stop traveling east at 5 mph. However, we all know when we stop our engine on our boat, we slow down.

How long it takes to go from 5 mph to zero depends on wind, and current. Even if there was no wind or current, we’d still slow down, because the water itself provides friction upon the hull of the boat, and that in itself acts as a brake.

We have all observed that the bigger the object, the longer it takes to slow down. Newton’s second law of physics talks about how the amount of force required to move an object is inversely proportional to the mass of the object.

So, if a tug and barge were traveling down a narrow channel, and you stopped your boat 1,000 feet away, right in front of the tug and barge; and, if the master of the tug saw you immediately; and if the master of the tug immediately began to stop the tug and barge; you’d have less than one minute to move your vessel.

If you didn’t move your vessel in less than 60 small seconds, the tug and barge would just run right over you. It would be impossible for the master of the tug to stop, based of the collective mass of both the vessel and the barge, in 1,000 feet.

The law of gross tonnage is un-relenting. It is a fact of life. Another fact of life is that you should not depend on the master of the tug or any other large vessel is able to see you, either visually or on radar.

Radar and Visual Lookouts

Radar, lookouts and even VHF radio’s all work the same. They actually work on the same basic principles of physics. Yes, physics that subject most of us hated in high-school rears its ugly head, yet again!

Think about it? Have you ever looked for something, but couldn’t find it, and it was right under your nose? How bout walking with a small dog, and it disappears on you, because it is right under your feet, but you don’t see it, because you’re looking further a field, away from you.

This same principle is at work with radar, and your VHF radio. The radar antenna on a large boat is raised much higher over the water. This enables the ship to see farther out to sea. However, on the downside, it also gives a larger blind area.

The radar waves generated from the antenna are narrow beams of energy. A properly configured radar antenna won’t begin to come near the surface of the water until its maximum state range. So a 24-mile radar will scoot high above the surface for large distances before the waves will begin to pick-up objects that are close to the surface.

Recreational boats are close to the surface. So, even though you may be a quarter-mile away from a large vessel, the lookout, be it human, electronic or both, may never be able to see you.

Lessons Learned

So, to sum up today’s lesson in physics. Don’t play in front of large ships. They are bigger, they are dangerous, and they may never see you.

Oh, before I forget – never pass between a tug and its barge! That may be the last thing you will ever do! In fact, stay as far away from a tug and barge, or for that matter any large vessel.

Between a tug and barge you’ll find a hawser (a large diameter line or cable), which will surely decapitate the boat and its occupants, should you collide with it. And all large vessels have large propellers, and prop wash. The forces made by these props are enough to either swamp your boat, drag it into the prop or combinations thereof.