Selecting the Right Radar for Your Boat

One of the most important pieces of equipment on any boat is the radar. This item is what allows pilots to navigate through the fog, determine their position when visibility is low, and much more.  Unfortunately, because it is fairly technical in nature, it’s one of the parts of their boat that owners understand the least.  When buying radar, a lot of people assume that the most expensive units on the market are the best, but that’s not always true.  Often, a small boat owner will purchase radar that does much more than what they need.  They’re spending money on features they’ll never use.  On the other hand, some owners under-spend and end up with radar that doesn’t provide much help at all during low visibility.  If you’re trying to decide which type of radar unit is right for you, here are a few things that may help.

Many people assume that the effective distance of an antenna is determined by things like power, quality, or bandwidth.  However, that assumption is wrong.  One thing determines how useful a radar unit is: the height of its antenna.  This is where some buyers go overboard, however, because just because you have an incredibly tall antenna doesn’t mean you’re going to be able to see everything.

Antenna Height

It’s a bit complicated.  First, radar is limited by the Earth’s curvature.  Second, you have to take into account the height of both your antenna and the object you want to see.  This determines if the radar is able to see the object over the curve.  There’s a mathematical formula that can be used to determine when you can see an object.  It looks complicated, but it’s not.

1.22NM x the square root height of your radar + 1.2NM x the square root height of your target.  Basically, if your radar is 4 feet tall and your target is 9 feet tall, the formula would be 1.22 x 2 + 1.2 x 3.  That means you’d need to be within 6.03 nautical miles before the radar would see the target.  Of course, you also have to take into account a few other things, such as the material your target is made out of.  Some materials such as fiberglass don’t reflect radar signals very well, which means you may not see the target until you’re much closer.

If your boat doesn’t have a tall mast or tower on it, a powerful long-distance radar isn’t going to do you much good.  Go with a unit that is better suited to your boat and save money.

Size and Weight Are Also Important

Before you purchase a large radar unit, make sure it will fit in your boat!  This seems obvious, but some owners buy the radar first, then measure the space.  Also take into account how heavy the antenna is.  Some small masts may not be able to hold that much weight.  In some cases, you may be better off going with a lighter, smaller radar unit since you can mount it higher up.


You also need to make certain you purchase a radar unit that can be integrated with your current electronics.  While it’s true that you can make most systems work together with a little jury-rigging, this mix-and-match approach isn’t the most efficient and may always be plagued with troubles.  It’s much better to have a radar that can be fully integrated with your system so you can make use of all of its functions.

Date of Manufacture

Finally, remember that radar units are basically computers.  Would you buy a laptop that was built more than four or five years ago?  Probably not since the technology in that laptop would be greatly outdated.  Radar is the same—advancements are always taking place, and even some new radar units that have only been on the market for about six months have been outclassed.  Look for radar that offer high definition signal processing, broadband connectivity, and high-speed data processing.  The newer models may be more expensive, but they’re much, much more powerful and have more useful features than those over a year old.