Article by Capt. Steve Katz
Tuning your Radar
With tournament season in full swing, there are a couple reasons to fine tune your radar operation skills.
While marine radar is primarily used for collision avoidance and navigation on the water, it can also be used to help us catch fish. We can think of our marine radar as another tool in our tackle box.
Let’s review the fun part of radar first, catching more fish.
While the radar can’t find the fish, it can find the birds that follow the fish. Often birds and sportfish both eat the same type of baitfish. If we find the birds, we can often find the sportfish below the birds. A stationary flock of birds is a good sign, indicating baitfish are below that area, where as quickly moving birds usually means they are searching for the fish and have not yet found them.
Adjusting and tuning your radar to find birds takes some practice and patience. It is easier if you have a good radar to start with, such as radar with a narrow beam width. The narrower the beam width, the greater target discrimination you will see on your display. Locating birds is best with an open array style radar since dome style radars do not have a narrow beam width. Additionally, as the length of the radar antenna increases, the beam width becomes narrower, so a larger antenna will offer better target discrimination.
Learning about your radar capabilities are best practiced on a clear, calm day. It is easiest to first visually locate a flock of birds that you want to target, and then see what they look like on your radar screen. To target the birds, set your radar to a low or medium range. Then slowly increase the gain control until you see noise (lots of small specs) on the radar screen, then stop adding gain. Too much gain will make it hard to determine if the return is a bird or clutter. The radar’s sensitivity increases with gain, so more gain is good, as long as you don’t flood the display with clutter.
During this tuning procedure you should have the AC/Sea, AC/Rain or any other anti-clutter adjustment all the way in the OFF or minimum position, often counter clockwise if you have knobs on your display.
Using the anti-clutter controls may reduce or eliminate the bird returns we are looking for. Flocks of birds may look like dense recurring noise or clutter and not a solid target. Learning what flocks of birds look like on your display, while actually looking at the birds in close range, will greatly help when you are searching on a longer range for feeding birds you can’t see by eye. Most captains are adjusting their radars to look for birds out to 6 miles or so, often much closer. The higher the birds in the sky, the farther distance you can see them on your radar.
If the flock of birds is moving, you can target them on your radar and see what direction they are flying, maybe they are heading to the fish! A radar navigation feature, called trails or echo trails, can be used to help determine the birds direction of travel (see picture). This feature indicates target movement by leaving an afterglow, showing where a target used to be. It is useful for quickly assessing the movement of targets relative to your own vessel. If you are using your boat to run towards the areas where birds are flying, adjusting your radar so that your vessel is at the bottom of the screen gives you more screen area in front of you. These tips are helpful when operating your radar in manual mode; some newer radar may already have a “bird mode” setting that will adjust the radar for you by optimizing the radar returns for birds instead of navigation.
Leaving the dock in the dark is difficult enough. Add a few hundred other boats and it can get busy and tough to navigate on the water. Using marine radar for collision avoidance and navigation on the water is its most popular operation. Radar should be used anytime you are navigating on the water, not just at night or when you have low visibility. A good marine radar can also show you thunderstorms, allowing you to change your course and avoid the storm.
When turning your radar, always start with all the controls and features in the off or low position. Start adding gain until you get too much gain, as indicated by many specs on the screen that are not actual returns. Reduce the gain slightly until the screen starts to clear up. If you are using your radar in the rain, you many need to reduce the clutter caused by the radar signals reflection from the rain. This is the “rain clutter” control. Slowly increase this filter until much of the false returns are eliminated and you can still see the true returns. If the sea conditions are rough, the waves may reflect the radar signal, showing up as clutter or noise on your display. Adjusting and increasing the sea clutter filter can help reduce this clutter, but be sure not to adjust sea clutter too much and confirm that you can still see the true returns. Over adjusting either of these controls can cause you not to see actual objects, especially the weak returns, like small fiberglass boats. Modern radars also offer automatic controls for all of the above settings, so be sure to try the different settings to learn how they affect the image on your particular radar setup. These features must be tested in clear, normal conditions so you can get a feel on how they work and what is best for your needs.
Practicing and learning with your radar will prepare you to confidently use your radar when you really need it for navigation and collision avoidance.
Captain Steve Katz is the owner of Steve’s Marine Service and holds NMEA, AMEI and NMEA2000 certificates along with ABYC Master Technician certification and factory training from many manufacturers.
