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Garmin Colorado 400c Review

The Garmin Colorado 400c is a very sophisticated full-mapping marine handheld GPS. A variety of Colorado models are available, while the hardware remains the same in each variant, the onboard cartography in each unit is different.

The Colorado 300 features a world base map, while each variant of the 400 adds specialized mapping. The 400t is preloaded with U.S. topographic maps, 400i has U.S. inland lakes, and our test unit the 400c packs U.S. Bluechart cartography.

garmin colorado 400c portable gps

Garmin Colorado 400c

A couple special features we found in this Garmin portable GPS series include the ability to transfer data from one Colorado to anther wirelessly and the ability to view images on an SD card. All Colorado handheld GPS units also have a built-in electronic compass and altimeter.

The 400c is packaged with a USB cable, carabiner clip, owner’s manual, quick start guide, and MapSource software.

The Colorado fits well in hand and measures 5.5-inches tall, 2.4-inches wide, and 1.4-inches thick. With a pair of AA batteries installed our 400c weighed in at 7.8 ounces.


The Garmin Colorado 400c is designed for easy one-handed operation with its pair of soft keys and Rock ‘n Roller™. The latter is a combination rotary knob, directional keypad, and enter button. This unit also has a top mounted on/off switch.

Pages are selected by pressing the shortcuts soft key. This open a graphic window with a user selectable page list.

Spinning the Garmin Colorado 400c Rock ‘n Roller selects a page, then pressing the center Enter button executes your choice. I found this to be a very fast and easy way to move from page to page and function to function.

I added the Route Planning page to the default list of pages so I’d have easy access to this function for testing later.

One page I was glad to see on the default page list was the Trip Computer, usually this type of page is buried somewhere deep in the bowels of a unit making it hard to find and use.

garmin colorado 400c portable gps

Use the right soft key to select shortcuts, then choose a page with the Rock ‘n Roller.

The Compass page is another default navigation page. This one features a compass rose powered by a built-in compass and four data boxes. The data boxes are of course all user selectable.

The Map page is also selected via the shortcut menu. It is very detailed and is by default set for auto ranging.

I much preferred manual map ranging and set things up that way by using the map setup menu. Once you do this the rotary portion of the Rock ‘n Roller becomes the default map range selector making setting the proper range fast and positive.

Waypoints and Routes

The easiest way to save a present position waypoint in the Colorado is to hold in the enter button located at the center of the Rock ‘n Roller for a couple seconds. A second quick press of the Enter key accepts the waypoint.

If you choose to edit the waypoint you’ll be directed to a menu that lets you change the name, symbol, comment, and position.

Since I had previously saved the Route Planning page in the shortcuts list all I had to do was select it to start the route building process.

If you want to build a route from waypoints already listed you’ll find it very easy. Just follow the menu prompts and click Enter as needed.

You can reverse a route by pressing the left soft key and choosing the option. The Garmin Colorado will store up to 1000 waypoints and 50 routes.

Display Screen

The majority of the 400c face is filled with a 3.0-inch color TFT display featuring a very high 240 x 400 pixel resolution.

garmin colorado 400c portable gps

Screen brightness can be adjusted from the Status page.

A single quick press of the on/off switch located on the top of the unit takes the screen brightness to maximum; a second press puts the system status page onscreen.

From here you can use the Rock ‘n Roller to set the screen brightness as needed. The date, time, battery status, and GPS signal strength are also displayed on this page.

The display screen was fairly bright when I viewed it outside with a high sun angle. It dimmed little when I donned my polarized sunglasses but did show some significant reflectivity.

Overall I am giving the Colorado screen a good rating for daylight viewing and an excellent for low light and nighttime viewing. In the dark, even when you tilt and move the unit to extreme angles the screen remains readable.

The Garmin Colorado 400c screen is capable of showing extremely fine detail not usually seen on small handheld GPS units.

Odds and Ends

This Garmin handheld marine GPS has a number of special marine information pages. Choosing the Where To? icon from the shortcuts menu lets you pick which one of these pages you’d like to see.

There is an Obstruction page that lists the range and bearing to exposed rocks or other dangerous obstructions. Selecting the obstruction takes you to the Map page with the obstruction shown onscreen.

garmin colorado 400c portable gps

Tide data is displayed onscreen in table format.

Another marine data page lists nearby tide stations, selecting one puts the data onscreen in table format. The Current page shows data in the same manner.

A navigation aid page lists those that are nearby with bearing and distance. Selecting one puts you back on the map page with navigation aid in view.

The Garmin Colorado 400c has some special features not generally seen on a marine handheld GPS unit. First, it can wirelessly share data with another Colorado unit, plus if you have an SD memory card with some photos the Colorado could display those photos onscreen. It also has an onboard altimeter.

Battery compartment access is gained by unfastening a latch on the back of the unit and then sliding the protective cover off.

In addition to the AA battery tray you’ll find the SD card slot in the bottom of the unit. A mini USB data port and external antenna jack are top mounted and protected from weather by form-fitted rubber flap.

This Garmin portable GPS is rated waterproof to IPX7 standards, meaning it can be submerged to a depth of 1 meter for 30 minutes without suffering any damage. It passed both our dunk test and drop test with no problem, but does not float. The unit carries a 1-year warranty.

Final Thoughts

The Garmin Colorado 400c has more and better marine capabilities than any marine handheld GPS we’ve tested to date. With its high-sensitivity multi-channel WAAS enabled GPS receiver, high-resolution color display screen, and easy to use software I am rating this unit a buy for any boater looking to get the best in a marine handheld GPS.

Buy this Garmin portable GPS here