Chartplotter and MFD Buying Guide: Screens, Charts and Networks
Before buying a new chartplotter or MFD, look at the system rather than just the screen. A marine electrician's view on displays, charts, networking and installation.
Most owners choose a chartplotter or MFD by screen size and price, but what really matters is how the unit will work as a system with the radar, autopilot, AIS and engine data on board. The wrong MFD can mean replacing a perfectly good radar or autopilot a few seasons later. In this guide we explain the criteria we use when refitting helm electronics, along with the mistakes we regularly find in the field.
Chartplotter or MFD?
A classic chartplotter displays the position from an internal or external GPS receiver on an electronic chart and manages routes and waypoints. An MFD (multi-function display) brings charts, radar, sonar, AIS targets, autopilot control, engine and tank data and even camera feeds together on one screen.
Almost every unit on the market today is an MFD. The real question is not "which screen" but "which ecosystem". On most brands, the radar scanner, autopilot computer and sonar module connect over the manufacturer's own Ethernet protocol. Choosing an MFD therefore sets the electronics architecture of the boat for the next 8–10 years.
The display: size, brightness and controls
Size and viewing distance
Choose the screen according to the distance between helmsman and display, not the length of the boat. A display 1.2–1.5 m away on a flybridge looks much smaller than the same unit at a lower helm. If you plan to use split screens (chart plus radar, for example), one size up is usually the right call.
| Use | Typical screen | Note |
|---|---|---|
| Small sailing yacht, cockpit wheel | 7–9" | Beside the wheel, clear of the helmsman's legs |
| 10–14 m sailing yacht / motor yacht | 9–12" | 12" is comfortable for split screen |
| 14–20 m motor yacht, lower helm | 12–16" | Often two displays |
| Flybridge and larger yachts | 16–24" or multiple displays | Synchronised over the network |
Readability in sunlight
On an open flybridge under the Aegean sun you need high brightness (most manufacturers quote 1000 nits or more), an optically bonded panel and an IPS screen that stays readable through polarised sunglasses. A model that is more than adequate in an enclosed wheelhouse may struggle in an open cockpit.
Touchscreen or keypad?
Touchscreens are pleasant in the marina, but in a seaway, with wet hands or gloves, a keypad or rotary knob is far more dependable. The best answer is a hybrid unit with both touch and physical keys, or a separate remote keypad.
One large screen or two medium ones?
A single 16" display looks more impressive than two 9–12" units, but if it fails you lose all your navigation information at one point. With two displays, one can show chart and AIS while the other shows radar or engine data, and either can take over every function if the other goes down. On yachts that make long passages, and on hard-working boats such as charter gulets, this redundancy is worth more than screen size. For a second display, also check route and data synchronisation between the flybridge and the lower helm.
Chart formats and updates
Which electronic charts an MFD can read is the most overlooked part of the decision. Navionics, C-MAP and the manufacturers' own chart sets are supported differently on different units. All of them are ultimately built on hydrographic office data and IHO standards; the differences lie in detail layers, update frequency and the user interface.
When choosing, ask:
- Is your cruising area (the Aegean, the Greek islands, the Eastern Mediterranean) available in that format?
- Are updates delivered by subscription or by swapping cards?
- Is there a high-resolution bathymetry layer for shallow, rocky areas such as the Bodrum bays?
Remember: no electronic chart shows every rock. In the coves around Gümüşlük and Yalıkavak in particular, always read the chart together with the depth sounder.
Before buying a chart card, also check the MFD's software version. New-generation chart cards may not be readable on units that have not been updated for a long time. Some manufacturers also sync charts through a phone app, in which case the boat needs Wi-Fi or mobile internet available during the update.
Networking: NMEA 2000, Ethernet and NMEA 0183
An MFD's real value comes from the network it sits on. Three types of connection need to be kept apart:
- NMEA 2000: the standard backbone on which position, heading, depth, wind, engine data and AIS are shared across brands. For a correct installation, read our guide to NMEA 2000 network installation and troubleshooting: a 120 Ω terminator at each end, drop cables no longer than 6 m and backbone power fed from the right point are the basic rules. The standard is owned by the NMEA.
- Ethernet (proprietary): radar imagery, sonar and multi-display sharing need high bandwidth and usually work only within one brand.
- NMEA 0183: still used by older instruments and some VHF/AIS units. The normal rate is 4800 baud, and 38400 baud for AIS; a wrong baud setting is the most common cause of "no data" faults.
If you are also renewing the radar and autopilot, our articles on boat radar installation and autopilot calibration will help you see which components need to stay within the same ecosystem.
Installation: power, location and GPS
A good MFD becomes a troublesome one when installed badly. These are the points we correct most often:
- Power supply: every MFD should be fed from the panel on its own fused circuit, with the fuse rating the manufacturer specifies. Limiting voltage drop on electronics circuits to 3% is good practice; if a 12 V system dips below 10 V during engine cranking, the display may reboot.
- Mounting position: the display needs airflow behind it and must not bake inside a closed box facing direct sun. The compass safe distance is printed on the unit's label and must be respected.
- GPS antenna: an internal GPS may struggle in an enclosed wheelhouse or under a carbon or metal hardtop. An external GPS antenna with a clear view of the sky prevents position jumps.
- Cable routing: leave enough room behind the unit for the bend radius, keep connectors out of drip paths and dress surplus cable without coiling it.
- Software: after installation, bring every device to the same software generation; mismatched firmware on a network causes silent data loss.
Pre-purchase checklist
- Compatibility with the existing radar, autopilot and sonar checked?
- Screen size chosen for the distance to the helmsman?
- If used outdoors, is brightness and readability through polarised glasses sufficient?
- Is your cruising area available in the chosen chart format?
- Can the NMEA 2000 backbone accept the new unit (terminators, power, a free T-connector)?
- Does the console cut-out match the old display, or is an adapter plate needed?
- Is backup navigation planned (second display, tablet or paper charts)?
The console cut-out is one of the items that most affects refit cost. Choosing a model that fits the old opening, or using an adapter panel, can avoid fibreglass and gelcoat work altogether. On motor yachts we plan this together with the wider motor yacht electrical project.
Work with Aslan Yacht on your helm electronics
Our Turgutreis-based team replaces chartplotters and MFDs, designs NMEA 2000 networks and integrates radar and autopilots in the marinas and boatyards of the Bodrum peninsula. We inspect your existing system on board and give you a clear list of what can be kept and what should be replaced. Explore our electronics and navigation services or get in touch to discuss your project.
Frequently asked questions
What is the difference between a chartplotter and an MFD?
A chartplotter essentially shows your GPS position on an electronic chart. An MFD (multi-function display) combines charts with radar, sonar, AIS, autopilot control, engine data and cameras on one screen; most units sold today are in fact MFDs.
Can I connect a radar or autopilot from another brand to my new MFD?
Core data such as position, heading, depth, wind and AIS can be shared across brands over NMEA 2000. Radar imagery and full autopilot control usually need the manufacturer's proprietary Ethernet link, which is why these components are normally chosen from the same brand.
Do I have to throw away my old NMEA 0183 instruments?
No. Most MFDs still have an NMEA 0183 input, or older devices can join the network through an NMEA 0183 to NMEA 2000 gateway. The baud rate (4800, or 38400 for AIS) and sentence types must be set correctly.
