Rek Bell — defensive boating

2024.03.10 This is a mirror of an article by Ken Taylor, excerpted from Small Boat Journal(July, 1990) and re-published digitally by Duckworks Magazine.

Defensive Boating

With traffic on inland waterways increasing every year, the land-bound commuter's motto is becoming increasingly applicable to small boat sailors: Watch out for the other guy.

So without getting into a lot of nautical jargon, procedures, and equipment, the following is meant to help you steer clear of trouble. In addition to being a basic law of the sea, collision avoidance will help keep your insurance premiums down, blood pressure steady, and make your day on the water more fun.

Unlike land-bound navigating, there are no apparent "roads" on the water to indicate the course of traffic. But there is a way to tell, as clearly as a stop sign at an intersection, whether you're likely to hit another boat.

Any boat coming in your direction and in front of where you're going has the theoretical potential to run into you. To go from theory to reality, all you need to do is look carefully at that other boat and the land behind it. Pick out a tall fixed object (a tree, telephone pole, or water tower) on the land behind the boat. From one spot on your boat, watch the other boat's movement relative to that fixed object. If after a minute or two of watching, the other boat does not move relative to that fixed object, you can conclude you're on a collision course with that boat.

a graphic showing a sailboat on a potential collision couse with another sailboat, and illustrates how to avoid a collision by using something in the background such as land, or a lighthouse, as reference

Don't panic. All you have to do now is adjust your course to avoid the other boat. There are all sorts of rules that govern right of way in a given situation (Seamanship, JBJ #60), and you should take the time to learn those rules, but in the real world, most newcomers to boating haven't learned these complex, extensive rules, so it's back to our maxim: Watch out for the other guy.

Avoiding Accidents

If you've determined another boat may soon slam into yours, you can't fool around with minor adjustments to course and speed. By law, you have to make adjustments large enough to be apparent to the other vessel.

Before making adjustments to your course, though, take a look around. Specifically, scan 360 degrees around your boat to make sure that when you change course or speed, you won't end up with another boat crawling up your transom or slamming you broadside. Again, boats approaching you from behind are required by law to stay out of your way. But in heavy waterborne traffic, if the skipper of that boat doesn't know the law, play it safe and take a good look around.

Once you've determined it's safe to change course and speed, you can do either or both, depending on what you think the situation demands. However, it can be easiest to just change course, especially if your means of propulsion is hard to adjust.

Course adjustment should be at least 45 degrees away from your current collision course (90 degrees, if possible). Make your course change quickly and obviously. This makes it clear to the other boater that you've changed course and that he should not interfere with your new course.

It's safest to turn in a manner that will let you pass off the offending boat's stern, although you're not required by law to do this. Trying to pass ahead of other boats somehow has the same effect as poking a snake with a stick. So when possible, pass off the other vessel's stern.

Keeping Your Distance

Adjusting your course to avoid a collision isn't the end of it, though. You have to make sure you don't come too close to the other vessel. This is known as giving a dangerous situation "wide berth" or "sea room."

Exactly how much room you should give the other vessel depends on how you've chosen to avoid it. If you're still insisting on passing ahead of the other boat's bow, you're going to have to go back to watching a fixed object behind that boat. You know you will pass well ahead of that boat if the fixed object behind it appears to be moving rapidly ahead of the boat. Conversely, if the fixed object appears to be moving behind the boat, you will pass well to its stern. You already know what happens if the fixed object doesn't move at all.

In very tight situations, the body of water may be only a couple hundred yards wide. In such a case, watching a fixed object won't do you much good.

There's usually not enough time or room for taking a reliable relative bearing. So you will have to use good judgement and the following basic "rule of three":

Try to stay at least three boat lengths away from sailboats underway, for they often must change course 90 degrees away from where they are headed. Wind conditions, rocks, shoals, and currents may force them to make these changes, sometimes without warning. So it's best to be well clear of all sailboats.
Maintain at least three boat lengths between your craft and powerboats that are trolling, To avoid running afoul of the fishing lines trailing out well astern of the boat, you should plan to pass some distance behind those lines.
Small boats should generally keep well clear of big boats by at least three boat lengths. (Definition: If it looks "big" from your boat, it is). Tugs with tows, seagoing ships, coastal freighters, and commercial fishing vessels at work can sweep a small boat (anything up to 35 feet) into the currents created by its propeller or equipment. Turbulence from these boats often stirs up prop-fouling debris from the bottom, especially in confined, shallow inland waters.

Last Attempts

Despite your best efforts, some day another boat is going to get on a collision course with you and stay there. When this happens, don't waste time trying to figure out what the other guy is up to. In the best commuter's tradition, use your horn.

The correct signal is five rapid, 1-second blasts on the biggest horn you can find. The compressed air horns found in most marine store are very effective. Remember: you're trying to alert the other boat to the danger of a very close situation.

The air horn also has many other applications. By law, it must be used in restricted visibility (fog, rain, etc.) or in certain maneuvering situations. Again, you will have to check the waterbome traffic laws for specifics.

If you follow the foregoing rules, you will already be in compliance with many of the formal rules. As the old saying goes, you have to start to be in the race.

KEN TAYLOR is a freelance writer and the owner of Seguin Navigation, a charter service in Arrowside, Maine.