When it comes to marine safety, few devices are as indispensable as GPS. While there are a number of different systems for marine navigation (everything from star charts to SatNav), nothing to date has matched the accuracy of cutting-edge GPS technology. With GPS, you can always find out your exact coordinates. Whether you are mapping a coastline, searching for a dive site, or just trying to find your way home, GPS can guide you to your destination.
Not sure where to start in your search for marine GPS? Check out the table below to compare features and prices for top-selling, highly-rated marine navigational systems.
Still have questions? Marine GPS comes with many features and options, and it is important to have a thorough understanding before you start shopping. Read on to learn all about marine GPS!
What is a Marine GPS?
GPS stands for “Global Positioning System.” GPS was developed by the U.S. Department of Defense for the military, but was made available to the public for commercial and civilian use thanks to an order from President Reagan. Originally, civilian GPS featured “Selective Availability”—which meant it wasn’t fully accurate. President Clinton did away with SA in 2000.
Now everyone can take advantage of GPS technology on land, sea, or air. GPS is available 24 hours a day and provides accuracy up to 15 meters.
How Does Marine GPS Work?
GPS took marine navigation to a higher level because it quite literally took it to new heights. GPS relies on a network of satellites which orbit the earth and which continuously transmit radio signals containing information on position and time.
While a precise explanation of how GPS works would require us to get quite technical, we can sum up the concept like this: Your GPS receiver “checks in” with several different satellites at once on an ongoing basis. Based on the differences between these signals and their time and positioning information, the receiver can extrapolate and figure out your coordinates.
The Marine GPS Advantage
Historically, mariners have used a number of different methods to try and determine their position—the stars, lorans, and SatNav are all examples. Each of these methods were useful, but they were also limited by weather and other factors.
GPS is far more powerful and accurate. Because the receiver tunes into satellites in orbit, you are always in range. You can check your position instantly in rain or shine. The information is constantly updated, tracking your movements. You can use your GPS to mark waypoints for future use, and you can even check your speed. Alarm systems can alert you when you are closing in on a waypoint or drifting away off course. You can even connect your GPS to other devices such as your autopilot, plotter or radar.
While GPS is the best navigational tool on the market for any mariner, never forget that power failures can happen. So never rely on any one device or method of navigation to stay safe!
Types of Marine GPS
There are several popular types of marine GPS. Let’s take a look at each.
Many people own a handheld GPS unit which they bring with them hiking, bicycling, or driving. A marine GPS unit looks very much like these, except that it includes marine charts. Handheld models are as portable as they come, and they tend to be less expensive than the other types as well. They have fewer features however and the small size of the screen may sometimes be inconvenient.
This looks similar to the type of GPS unit which is typically installed in the dashboard of a car. The screen is a bit larger than that on a handheld model, and usually offers touch navigation. You do need somewhere to mount one in order to use it, as these devices are too heavy for comfortable handheld use.
These are the largest marine GPS units and come with a mount. They do tend to be the most expensive, especially if you purchase the touch screen variety. If you are willing to pay even more, you can get a unit which you can network with your radar and sonar.
There are two very important features which come with most marine GPS units and which are worth discussing in depth before we get into questions for buying. The first is called “chartplotter.”
Chartplotter is basically a suite of tools which are extremely useful when you are navigating at sea. The vast majority of marine GPS units come with it. Some of the features and benefits of chartplotter include:
- Continuous monitoring of your exact position with relation to geographic features above and beneath the waves.
- Real-time tracking of boat speed and direction.
- The ability to set and load waypoints and routes.
- Store numerous routes for future use (some devices will allow you to keep hundreds). Load them instantly when you want them.
- Extra features: Zooming, man overboard markers, and more.
Remember, always keep some paper charts handy in case of a power failure.
If you are a fisherman, you definitely will want to look for a marine GPS unit which includes a fish-finder. A fish-finder uses sonar technology to measure the depth of the water and also to track the positions and movements of fish. This allows you to lower nets and lures to just the right depth to catch unwary underwater denizens.
Questions to Ask When Shopping for a Marine GPS
What is the main purpose of your marine GPS?
Before you can choose the right marine GPS unit, you need to ask yourself why you are buying it. Is it mainly for safety purposes for the occasional leisure trip? For exploration? For diving? For fishing? For commercial shipping use? Only after you establish your reason will know what features to shop for.
Will you be traveling a lot of different routes?
Chartplotter is an important feature to shop for no matter what, but you should consider specific chartplotter features in conjunction with storage capabilities. If you are in shipping or you do a lot of exploration up and down the coast or far out at sea, you should look for a device which allows you to store hundreds of routes.
Do you fish?
If you like to fish, you definitely should make sure you get a device with fish-finder! Otherwise, skip it and save some money.
What do you need more—portability or a big screen and lots of advanced features?
If you need a device just for irregular use—maybe the occasional recreational trip out in a sailboat—a handheld or portable device may be sufficient and save you money. But for regular, lengthy or commercial excursions, you definitely should consider a fixed-mount model which you can sync up with your other devices. This will keep you safer, simplify navigation, and free up your hands to work on other tasks.
Features and Add-Ons to Look For When Shopping for a Marine GPS
Adequate screen size and resolution
It is important to try and purchase a GPS with a reasonably large screen and high resolution. Screens which measure at least 5” diagonally are best; others squeeze the view too much when using zoom or split screen. The higher the resolution the better—you will be able to see more detail.
Less expensive marine GPS devices feature an output of around 100-300 watts. This is sufficient if you are fishing at a depth of 200’ or less, but for deep sea fishing, you need more power.
The transducer in your fish-finder focuses the beam. The more focused that beam is, the deeper it can penetrate—even at the same power level. If you double the diameter of the transducer crystal, it will have the same effect as quadrupling the power.
Obviously at sea, there is a chance your marine GPS will get wet. Water resistance prolongs its useful life and makes it more likely it will function when you need it most.
- IPX0: No water resistance.
- IPX1: Protection from vertical drops.
- IPX2: Protection from vertical drops and drops at an angle 15 degrees.
- IPX3: Protection from spray up to 60 degrees.
- IPX4: Protection from splashes in any direction.
- IPX5: Protection from water jets from any direction.
- IPX6: Protection from powerful jets.
- IPX7: ACTUAL WATERPROOFING in up to three feet of water.
- IPX8: ACTUAL WATERPROOFING in more than three feet of water.
Being able to take barometric pressure readings can help you to track storm systems while you are at sea.
While your basic marine GPS can track your position, it cannot tell which direction you are facing. That means it can only tell you if you are going the right way when you are moving—but it cannot point you in the right direction when you are still. For that, you need an electronic compass.
Additional charts and maps
You can also buy additional maps to go with your marine GPS device. Obviously the more built-in maps and charts your device includes, the better—but you may wish to shop for detailed maps of areas you frequent which include enhanced contours and labeling. This can streamline navigation.
You now should have a great idea where to begin in your quest for the perfect marine GPS unit. Start by asking yourself why you need the device and how you plan to use it. This will help you identify the features which are most important to look for. Scroll back up to the top of the page to shop for top products using our comparison chart!
Garmin GPSMAP 78sc: Perfect for Sailing
Amateur and professional seafarers alike will appreciate Garmin’s 78sc marine chartplotter. Its display is easy to read at any time of the day, plus the depth alarm feature will keep you from running aground.
- Awesome display. Some displays are hard to read in direct sunlight, but the Garmin GPSMAP 78sc’s screen is easy to read no matter what time of day (or night) it is.
- Extended battery life. You can get 30 hours of continuous use or more out of this device, which is more than enough for a full day of sailing.
- Fast performance. The processor is powerful enough to allow you to switch screens with ease.
- Garmin technology. Like most Garmin products, the Garmin GPSMAP 78sc features excellent support and an easy-to-use navigational interface.
- Floats on water. If you drop this device into the ocean, no problem. Just scoop it up and keep on sailing.
- Man overboard button. If someone falls off the boat, hit the man overboard button to mark their position on the map.
- Depth alarms. The depth alarm allows you a chance to avoid running aground when navigating shallow water environments.
- The optional maps for this device are quite nice, but they are also pricey.
- Some people who tried the Garmin GPSMAP 78sc didn’t like the fact that the display is not a touchscreen.
Garmin GPSMAP 547: Split Screen Functionality
The best thing about the GPSMAP 547 is how customizable it is. This device allows you to easily personalize and tweak your display so that the information you think is important is always on hand.
- Plug and play. Setup is super easy and should take most people just a few minutes to complete.
- Split screen functionality. This GPS map’s convenient split screen feature allows you to view extra information as you’re navigating.
- Music app. Garmin Helm allows you to pipe in music through your Garmin GPSMAP 547.
- Excellent quality fishfinder. This device’s built-in fishfinder actually works better than some standalone fishfinder devices.
- Responsive performance. The Garmin GPSMAP 547’s powerful processor allows you to quickly cycle through menus.
- Plot routes from your smartphone. With Garmin Helm, you can plot out a route and upload it the next time you’re close to your Garmin GPSMAP 547.
- Accurate GPS. This device’s GPS system always delivers reliable readings.
- The instructions that come with this product are confusing and hard to read.
- The Garmin GPSMAP 547’s button controls are easy enough to figure out. But if you’re used to touchscreen displays, you might lose patience with it.
Garmin Striker 4: Tough and Affordable
With its thick, heavy-duty shell and rubberized buttons, Garmin’s Striker 4 won’t let you down when the weather gets rough. It’s the perfect navigational device for canoers and small boat fishermen.
- Display looks good in the sun. This device’s bright, detailed display always looks good.
- Affordable. The Striker 4 is cheap compared to most competing marine chartplotters.
- Resists nicks and dings. This product’s reinforced plastic shell is definitely built to last.
- Highly accurate fishfinder. The addition of CHIRP sonar technology is a nice touch.
- Simple navigation. Like most Garmin GPS devices, the Striker 4’s interface is simple and easy to use.
- Very portable. This device’s low profile makes it ideal for ice fishing, canoeing and other marine activities that require you to manage your storage space in a strategic way.
- Comes with everything you need. The Striker 4 comes with a CHIRP (77/200 kHz) transducer, transom and trolling motor mounting hardware and connection cables.
- The Striker 4 doesn’t use “true” GPS maps. You have to enter in waypoints to find your way around.
- This chartplotter was designed to be used in cramped conditions. But if you have plenty of storage space, you may not appreciate the Striker 4’s extra small screen.
Humminbird Helix 5: Helps You Reel In More Fish
If you want to reel in more fish more often, a fish finder like the Humminbird Helix 5 can help you step your game up. Its powerful sonar transmitter, side imaging technology and its bright, backlit display will let you know exactly when and where to drop your line. Another nice thing about this fish finder is that it comes with free mounting hardware.
- Expansion slot. With the Helix 5’s handy microSD card slot, the only limit to the amount of maps you can bring with you is the number of SD cards you own.
- Brilliant display. This GPS unit’s 5 inch, backlit, 800×480 color display is one of its strongest selling points.
- Great for small boats. The Helix 5 works especially well while kayaking or rafting.
- Side imaging. Humminbird’s excellent side imaging technology allows you to know where to go to catch more fish.
- Powerful sonar. The Helix 5’s powerful sonar system enables you to see what’s happening 1,500 feet below the surface of the water.
- Mounting hardware included. This unit comes with a mounting bracket, power cord and a transducer.
- Adjustable filters. Use “max” mode to see everything, or “clear” mode to filter out smaller fish and debris.
- This flexible and customizable marine GPS unit is handicapped by the fact that its built-in maps aren’t very impressive.