The chart below shows many of the current Garmin Marine fixed mount chart plotters. They are listed in numerical order by their model number. All models have an SD slot to add charts, 0183/2000 NMEA, and an internal antenna. Some of the features are described at the bottom of the page.
| Model/ review |
Touch screen |
Display Size |
Resolution | Preloaded Charts |
Waypoints/Routes Trackpts/Tracks |
Sounder Module |
Add Radar |
Check price |
|---|---|---|---|---|---|---|---|---|
| 421 | No | 2.4″ x 3.2″ | 240 x 320 | Basemap | 3,000/100/10,000/50 | No | No | Amazon |
| 421s | No | 2.4″ x 3.2″ | 240 x 320 | Basemap | 3,000/100/10,000/50 | Yes | No | Amazon |
| 431 | No | 2.4″ x 3.2″ | 240 x 320 | U.S. Inland | 3,000/100/10,000/50 | No | No | Amazon |
| 431s | No | 2.4″ x 3.2″ | 240 x 320 | U.S. Inland | 3,000/100/10,000/50 | Yes | No | Amazon |
| 441 | No | 2.4″ x 3.2″ | 240 x 320 | U.S. Coastal | 3,000/100/10,000/50 | No | No | Amazon |
| 441s | No | 2.4″ x 3.2″ | 240 x 320 | U.S. Coastal | 3,000/100/10,000/50 | Yes | No | Amazon |
| 521 | No | 3.0″ x 4.0″ | 234 x 320 | Basemap | 3,000/100/10,000/50 | No | No | Amazon |
| 521s | No | 3.0″ x 4.0″ | 234 x 320 | Basemap | 3,000/100/10,000/50 | Yes | No | Amazon |
| 531 | No | 3.0″ x 4.0″ | 234 x 320 | U.S. Inland | 3,000/100/10,000/50 | No | No | Amazon |
| 531s | No | 3.0″ x 4.0″ | 234 x 320 | U.S. Inland | 3,000/100/10,000/50 | Yes | No | Amazon |
| 541 | No | 3.0″ x 4.0″ | 234 x 320 | U.S. Coastal | 3,000/100/10,000/50 | No | No | Amazon |
| 541s | No | 3.0″ x 4.0″ | 234 x 320 | U.S. Coastal | 3,000/100/10,000/50 | Yes | No | Amazon |
| 526 | No | 3.0″ x 4.0″ | 480 x 640 | Basemap | 3,000/100/20,000/50 | No | No | Amazon |
| 536 | No | 3.0″ x 4.0″ | 480 x 640 | U.S. Inland | 3,000/100/20,000/50 | No | No | Amazon |
| 536s | No | 3.0″ x 4.0″ | 480 x 640 | U.S. Inland | 3,000/100/20,000/50 | Yes | No | Amazon |
| 546 | No | 3.0″ x 4.0″ | 480 x 640 | U.S. Coastal | 3,000/100/20,000/50 | Yes | No | Amazon |
| 546s | No | 3.0″ x 4.0″ | 480 x 640 | U.S. Coastal | 3,000/100/20,000/50 | Yes | No | Amazon |
| 720 | Yes | 6.0″ x 3.6″ | 800 x 480 | Basemap | 3,000/100/20,000/50 | No | Yes | Amazon |
| 720s | Yes | 6.0″ x 3.6″ | 800 x 480 | Basemap | 3,000/100/20,000/50 | Yes | Yes | Amazon |
| 740 | Yes | 6.0″ x 3.6″ | 800 x 480 | U.S. Coastal | 3,000/100/20,000/50 | No | Yes | Amazon |
| 740s | Yes | 6.0″ x 3.6″ | 800 x 480 | U.S. Coastal | 3,000/100/20,000/50 | Yes | Yes | Amazon |
Feature explanations
- Preloaded Charts – These are the charts loaded into the memory of the Chartplotter. Some units come with just the worldwide basemap, which is a very rough outline of the worldwide landmasses. Basemap does not include any depth spot soundings, bottom composition, shore facilities or shoreline detail. Inland charts include inland lakes and streams in the United States. Coastal charts are the coastal regions of the United States. Both Inland and Coastal charts include the Great Lakes. Neither Inland or Coastal include detailed charts of any foreign country such as Canada, Mexico or the Bahamas.
- Ability to add maps/storage – Units with pre-loaded detailed charts are stored internally. Internal storage can not be loaded with any additional charts. Additional charts are optionally added with the SD/microSD card slot. BlueChart G2 Vision charts have functionality and chart views that are not available with internally stored charts. Views such as MarinersEye and FishEye can only be used by adding a BlueChart G2 Vision card. MarinersEye is a 3D bathymetric representation of the bottom contours from above the waterline and FishEye is a 3D bathymetric view of the bottom contours from below the waterline. Charts for many foreign countries can be added with a card.
- Waypoints/Routes and Trackpoints/Tracks – The numbers listed are the number of waypoints and routes that can be saved, followed by the tracklog capacity and number of tracks that can be saved.
- NMEA – NMEA stands the National Marine Electronics Association. There are two industry standard NMEA communication options. NMEA 0183 works on a serial bus, and is an older standard established to allow electronics from different companies to communicate. With NMEA 0183 there is no standard connector. Most often the wires from two devices need to splice together. NMEA 2000 (N2k) is a CAN based networking standard. NMEA 2000 is not compatible with NMEA 0183. The N2k network has one central backbone cable. All devices are connected as drops from this central backbone. The backbone can power some of the devices on the network, while other devices might require their own separate power. A standard connector has been established that should make all devices “plug and play” with the rest of the network. Some examples of NMEA 2000 attached devices: autopilot, GPS sensor, weather sensors such as windspeed and direction, AIS, VHF/DSC, fuel flow, fuel level, engine diagnostics. While many types of sensors can be added to the network, not all displays will display all data from all sensors.
- Sounder Module – High frequency sounds can be sent through the water to reflect off the bottom and also reflected off fish. By measuring the time the signal takes to reflect back to the boat, and the amplitude of the reflected signal, the depth of water and/or presence of fish can be determined. Providing this functionality requires two devices: a sounder module and a transducer. The transducer must be mounted below the water line. Some common examples of transducers are transom mount, through hull, and in hull. The transducer is connected to the sounder module. The sounder module is the brains that controls the transducer. The sounder module will not function unless connected to a transducer. Some of these units have a sounder module built in, some units offer it as an optional black box that can be added, and some units have no sounder functionality at all.
- Antenna – Some units have the antenna built into the unit. Some units require a remote antenna that must be mounted elsewhere on the boat. The remote antennas often resemble the shape of a mushroom.
- Radar – Some units allow the addition of Radar with an ethernet port. The ethernet port may connect to connect to a proprietary network that has radar attached, or the ethernet port may connect to Radar only.
- Wireless – Some recently announced units allow wireless connection to the Garmin Bluechart Mobile app that runs on smartphones and tablets.
About the author – Bob MuellerP/C Bob Mueller, JN is an active member of the United States Power Squadrons. He is an ABC3 instructor, a Vessel Safety Examiner and a Squadron Emergency Response Assistance Team Leader. Learn more about P/C Bob Mueller, JN at bereapowersquadron.org.