Situational Awareness

I get several flying magazines each month, and without fail first articles I read are in the columns called “I-almost-crashed-last-month” or “Boy-what-a-dope-I-am.” These articles are great because 1) they make you feel like there’s someone out there even dopier than you (a bittersweet thought!), and 2) they reinfoce the serious responsibilities you have as a pilot. As a boat owner your responsibilites are no different, and we can learn a lot about safety and navigation from our airborne friends who use their electronics collectively to give them a complete picture of the situation around them.

Pilots refer to this as “situational awareness,” and careful attention to it while relying on instruments can help prevent disorientation, collisions, and other episodes that wind up in the back pages of flying magazines. We boaters can also use the techniques of situational awareness to keep us safe at sea, but to do this we need to stop thinking about our electronics as individual units, and instead think of them as information providers that can be combined to give us the big picture underway. The key instruments we have are the depthsounder, the radar, and the GPS/electronic chart, and here’s how you can use them collectively to improve your own sense of situational awareness.

Depthfinder/Fishfinder: In the air, pilots use the altimeter to tell them how far above sea level they are. They obviously operate in a three-dimensional environment, but too many boaters make the mistake of thinking that just because they’re “stuck” at sea level, they’re only in a 2-D environment. That would be true if the depth below your boat remained constant, but in fact your depth, or if you prefer your “altitude” above the bottom, is constantly changing as you move, so you must be very much aware of it. While you might not check your depth gauge while fishing offshore in the canyons, this instrument becomes vital as you make landfall, and even more critical during harbor approaches. If you have a fishfinder, so much the better, because while the depth gauge only shows instantaneous depth information, the fishfinder shows the depth’s trend line beneath the boat, and that may save you from running aground if the bottom’s coming up quickly and you react correctly. For the ultimate in underwater collision avoidance, a forward-scanning sonar can show a reef ahead of you before you tangle with it, and a side-scanning sonar is excellent for keeping you safe when navigating in areas littered with boulders and small islands.

So when entering a harbor—particularly an unfamiliar one—you should think of your vessel as being on “final approach,” and keep one eye ahead and one eye on the depth gauge until you are safely tied down at the dock.

Radar: Most recreational boats 35-feet and larger are equipped with radar, and this is your primary tool for avoiding collisions with other vessels. Since we don’t have boat-traffic controllers to warn us of imminent collisions we have to do it ourselves. But our traffic problems are compounded by the fact that while aircraft can fly at a variety of assigned altitudes, we only have one—sea level—so that puts all vessels on the same vertical plane, increasing the risk of collision.

In restricted visibility such as rain or fog, a good radar can be a lifesaver since it will alert you to most (but maybe not all) of the vessels around you so you can take appropriate action to avoid collision. To use the radar effectively, as visibility decreases, so should your speed and the radar range you’re using. There’s no sense in looking out 12 miles in dense fog when a lobster boat could be bearing down on you from 500 yards away. The range you use in fog is largely determined by your vessel’s maneuverability, but for most recreational boaters, switching back and forth between the 3-mile and ½-mile ranges should be plenty of protection. Also, learn how to set up your unit’s “guard-zone” feature so that if a target penetrates that zone on your radar screen you will be alerted to it right away.

In addition to collision avoidance and knowing where all the other guys are around you, remember that the radar can also help determine your position even without the use of an electronic navigator. If the paper chart shows there’s a point of land jutting out on your starboard side, you can locate that point on the radar and use the unit’s electronic bearing line (EBL) and variable range marker (VRM) to pinpoint your position relative to that point. This one-two punch of providing both collision-avoidance and navigation information makes the radar supremely important for safe navigation in restricted visibility situations.

GPS/Electronic Chart. With just the information above, we know how deep we are and where other vessels are, but we still might not know where we are. Here’s where the GPS/electronic chart combination comes in. A stand-alone GPS receiver will gives you a latitude/longitude position fix usually good to +/- 100 feet, and a fix from a differential GPS receiver is accurate to +/- 30 feet or better. You can then take this latitude/longitude information and plot it on a paper chart to find your instantaneous position. If you do this at regular intervals while cruising from one destination to another, you can compare your actual track based on past position fixes (“course over ground”) with your intended track, and then you can adjust your heading accordingly to keep your vessel on course. But a GPS/electronic chart unit can show you all of this information graphically on an LCD or CRT display, minimizing the work you have to do to stay aware of your position.

While all electronic charts will let you create routes by connecting a series of waypoint together which will get you from point A to point B, an often-underutilized feature is the so-called “3-D steering highway,” which actually resembles a runway more than anything else. If you’ve plotted your course carefully, and made sure your route will not take you over any reefs or other obstructions, then you can simply watch the 3-D highway underway so you’ll hug the centerline of your route at all times. By keeping your vessel on the highway’s centerline, you are also compensating automatically for the effects of any current set and drift, and this not only keeps you on course, but saves fuel, eliminates disorientation, and increases your overall situational awareness

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As we’ve seen, today’s marine electronics can provide an array of very specific data about your position in space and the positions of other vessels around you. But in the end there is only one “machine” that can accurately accept, interpret, and evaluate all of this data simultaneously, and that’s your brain. You must become familiar with your equipment—including each unit’s limitations and possible false readings—in order to make an accurate appraisal of the situation around you. But once you’ve accomplished that, you can be as good or even better than any airline pilot in the all-important skill of situational awareness.