Safety & Seamanship -- Rules of the Road


Bowsprits are not for ramming. Rub rails and swim platforms are not bumpers. We need to ensure that all intimate contact between (and on) boats is consensual. Boats (and perhaps, surprisingly, ships) are delicate things and do not take well to being in close proximity to one another.

In fact, even a very modest contact of the type that would be shrugged off by the “2.5-mph bumper” (5 mph before May 1982) on one of today’s cars can cause costly damage to a yacht.

The physical damage that can occur from even a minor collision is often made more serious because the occupants of a vessel are rarely, if ever, restrained with seatbelts (much less shoulder straps), and in most cases little or nothing has been done to delethalize their surroundings. Bang two boats together, and people can get hurt, sometimes fatally. No doubt about it, we need a way to avoid collisions.

We have a set of rules that govern how we drive our cars (if they were always followed we wouldn’t need the 2.5-mph bumpers). Likewise, we need a set of rules to govern how we navigate our boats. However, the rules for vessels will necessarily be more comprehensive and complex than those required for wheeled vehicles, whose path is usually constrained by the roads on which they travel. Boats can go virtually anywhere except where their draft exceeds the depth of the water — and that limitation doesn’t seem to bother some people — and can approach one another from any direction at any angle.

The rules under which all vessels in the United States must navigate are simply called the Navigation Rules, International-Inland, published by the Coast Guard. The International Rules have their origin in the International Regulations for Prevention of Collision at Sea (1970), of which the United States is a signatory. The Inland Rules were adopted into U.S. law by the Inland Navigation Rules Act of 1980. With few exceptions (see Rule 34 — Maneuvering and Warning Signals), the International and Inland Rules are virtually synonymous in content. The only difference is the geographic area where they apply, as denoted by their titles. Both are contained in a single book, with the International Rules on the left page and the Inland Rules on the right for easy comparison. It is available from numerous commercial sources and online at

If your vessel is 12 meters (around 39 feet, 6 inches) or greater in length you must have a copy of the Inland Navigation Rules on board for ready reference. Edition D is current and includes changes made in 2003 that largely dealt with Wing In Ground Craft. (If some of the projects now under way succeed you might encounter one of these aircraft-like vehicles flying a few feet above the water at speeds that can exceed 100 knots.)

Are the Nav Rules daunting? Ask anyone who has ever taken a Nav Rules test, and the answer may be yes. Technically, there are a total of 38 rules grouped into five parts: A. General; B. Steering and Sailing; C. Lights and Shapes; D. Sound and Light Signals; and E. Exemptions. Although they have the force of law, they were written by mariners for mariners, and there is not a single “whereas” or “wherefore” to be found. The good news is that only professional mariners have to pass a Nav Rules test, whereas the rest of us marine mortals only have to know them well enough to make sure we avoid collision.

A comparison between road rules and vehicle rules can be seen by comparing the “passing” situation in a car with those that apply when passing another vessel. To pass a slower-moving vessel we signal our intention in the form of a proposal with a whistle signal. Vessels are required to use whistle or horn signals (or, by agreement with the other vessel, bridge-to-bridge VHF channel 13 radio communication) in place of turn signals. Although many recreational vessels fail to make any sound signals — and we rarely hear them on channel 13 — the signals are required by law and are a courtesy we owe each other if we wish to be considered mariners, not boat drivers.

Ultimately, the skipper must do
whatever is neccesary to avoid a collision.

Like most everything else in the Rules, the sound signals are easy to remember and easy to respond to. On inland waters, sound one short blast or toot if you propose to pass another vessel on your port side (remember, port is one [italic “one”] syllable), whether on a meeting or overtaking situation. Two short blasts means you propose to pass on your own starboard side (remember, starboard is two [italic “two”] syllables), whether meeting or overtaking. Three whistles tells anyone in earshot that your engine is operating astern, regardless of the direction in which your vessel is moving.

You signal your agreement with another boat’s sound signal by sounding the same signal. If for any reason you don’t understand or don’t agree with the maneuver announced by another vessel’s whistle, sound five or more short blasts on your horn. For example, if you wish to overtake a vessel moving in the same direction, two short whistles signal the other skipper that you propose to pass on his port and your starboard side (the two-syllable word). If he agrees he will respond with the same two-whistle signal. If for any reason he doesn’t agree with your plan — perhaps he can see people in a canoe ahead that you can’t see — he will sound the five or more “I don’t understand or doubt it will work” whistle signal, and you must abandon your proposed maneuver. The same procedure is used when meeting an oncoming vessel, although in this case you would normally sound only one whistle to signal your intention to alter course (even if only slightly in a wide channel) to starboard to pass port-to-port.

The maneuvers needed to safely pass or meet another vessel are clear and usually easy to plan and execute. The situation that occurs when vessels are converging can be much more challenging. The basic rule that governs the way you will maneuver your vessel is straightforward and is defined in terms of how you see the other vessel’s running lights (or would see them if they were illuminated). If you see a green running light you are the privileged or stand-on vessel and are obligated to maintain your course and speed. If the light you see is red you are the burdened vessel and are required to give way to the privileged vessel. If both skippers know and follow the rules, the likelihood of a collision is greatly reduced. However, such risk may continue to exist, and ultimately you are required to do whatever is necessary to avoid a collision.

It is a wise mariner who remembers that we share the water with merchant ships, cruise ships, tugs and fishing vessels, virtually all of which are much larger and less maneuverable than our vessels. We need to know and adhere to the Navigation Rules while always recognizing that the larger vessel may not be aware of our presence and, in any event, may not be able to maneuver to avoid collision. We must do whatever is necessary to avoid a collision.

Next time you are on your boat — or sitting at your computer — take the time to read or reread the Navigation Rules. You will find that they are likely the most clearly written government document you have ever read. Examine the illustrations of lights and shapes. You won’t remember them unless you are preparing for a Coast Guard license exam, but at least you will remember where to find them when you need them. A quick reference Navigation Rule card at the helm might be your best ever $10 investment.

This story was taken from “Seamanship & Safety” (2007), part of Soundings Publications’ Master’s Series. 

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