Pay Attention to Details

There aren't too many mariners operating recreational vessels that are graduates of a maritime academy. Overall, we've learned what we know about boat handling and safety while "on the job." When it comes to knowledge of charts, navigation publications and aids to navigation, most of us have acquired a little bit here and a little bit there.

There are a few subtle aspects about the way that "aids to navigation" (buoys, dayboards, etc.) are positioned on our waterways. There are some things that we can learn by "paying attention to details."

There are several questions that are in the minds of more than just a few boaters. Why are certain channels only marked on one side? Why are channel markers 500 feet apart on one waterway and 5 miles apart in another?

Lets start with the spacing. First of all, when we are traveling from "mark to mark," most of us would say that we are "in the channel." The fact is that not all routes along our waterways are channels. Sometimes the route that we're on is in a 5-mile wide body of water, 4 miles of which are of navigable depth. We call that situation a "fairway" and not a "channel."

A channel is a narrow "trough" within which the water depth is sufficient for vessel traffic. A channel is flanked by very shallow water on at least one side, and in most cases both sides. When your chart shows a black dashed line marking both edges of the navigable waterway, you are definitely in a "channel." Many mariners refer to this situation as a "tight channel."

When you are in a "tight" channel, the buoys and daymarks are closely spaced to assist you in staying within the channel. Generally, in this situation, a slight deviation from the marked channel will cause you to go aground. If the channel marks are too far apart, and there is a wind or current abeam of you, it would be difficult to stay on track between the marks.

On the other hand, if you are in a 4-mile wide "fairway," the aids to navigation are simply marking the "route." They are not there to confine you within a few hundred feet where the deep water is. In this case, these marks may be several miles apart. As long as mariners can see them sufficiently to follow the route, their mission is accomplished.

As a rule of thumb, when your chart shows aids to navigation at 500 foot spacing, you need to be paying attention to staying in the channel. When the spacing is a few miles or more, you need to travel from one to the other, but the risk of going aground is far less than the earlier example.

As far as marking both sides versus one side of a channel or fairway, the surrounding water depth is a factor. If the navigable depth changes abruptly on one side and changes very gradually on the other, the "shallow" side may be the only one marked. It saves the taxpayers money!

The next time that you're on a trip through a waterway that involves a large number of buoys and dayboards, take note. As Yogi Berra once said, "You can observe a lot just by watching."

Until next time, I wish you clear skies, fair winds, and calm seas!