Fishfinder or Chartplotter: How to Choose the Right One
Walk into any marine electronics catalog and the same question comes up: do you need a fishfinder, a chartplotter, or one of the combo units that claims to be both? The honest answer depends on the boat, on how you fish, and on one component most buyers overlook until the end: the transducer. This guide sorts it out with the units we actually stock in Pompano Beach, in our chartplotters and fishing and sonar categories.
Fishfinder, chartplotter or combo
A fishfinder is sonar: a transducer under the boat sends sound down and the screen draws what bounces back, so you see depth, bottom hardness, structure and fish. A chartplotter is navigation: GPS position drawn on a nautical chart, with routes, waypoints and hazards. A combo, also called an MFD, does both on one display, and that is what most of the market has become. The Garmin GPSMAP and ECHOMAP lines, Lowrance Elite FS and HDS PRO, Simrad NSS and Humminbird XPLORE and APEX are all combos: the difference between them is screen size, sonar capability and how far the unit can grow into a network.
The practical rule: if you only ever fish one small lake you already know, a dedicated fishfinder is enough. If you run any open water in South Florida, buy a combo. The chart side is not a luxury here, it is how you avoid the shoals.
Match the screen to the boat
Screen size is the biggest price lever and the first spec to fix. Bigger is genuinely better, but only up to what the helm can fit and what you sit close enough to read. Every unit below was in stock at the time of writing:
| Screen | Typical boat | In stock now |
|---|---|---|
| 4 to 5 inch | Skiffs, jon boats, first unit on a budget | Garmin STRIKER Vivid 4cv, Garmin ECHOMAP UHD2 54cv |
| 7 inch | Center consoles and bay boats under 25 ft | Lowrance Elite FS 7 with 3-in-1, Garmin ECHOMAP UHD2 73cv |
| 9 inch | Serious fishing boats, split sonar and chart | Lowrance HDS PRO 9, Garmin GPSMAP 943xsv, Humminbird XPLORE 9 |
| 10 to 12 inch | Offshore boats, multiple views at once | Lowrance Elite FS 12, Garmin GPSMAP 1042xsv, Simrad NSS 4-12 |
| 16 inch | Sportfish and yacht helms, full glass bridge | Lowrance HDS PRO 16, Garmin ECHOMAP Ultra 2 16, Humminbird APEX 16 |
The transducer decides what you actually see
Two boats can run the same head unit and see completely different pictures, because the transducer does the seeing. Traditional CHIRP sonar draws arches under the boat. Down and side imaging paint photo-like views of structure to the sides and below. All-in-one transducers, like the 3-in-1 units Lowrance bundles with the Elite FS line, combine those views in one housing.
This is also why so many combos are sold two ways, with and without a transducer. The display alone suits owners upgrading a screen while keeping a compatible transducer they already have. A first install is usually simpler with the bundle. If you are matching a transducer to an existing unit, or want to step up to imaging the head unit supports, our transducers category is organized by brand and mounting style.
Think about the network before you buy
Modern units talk to each other over NMEA 2000. That matters even if today you only want one screen: a combo with NMEA 2000 can later share data with an autopilot, a VHF with GPS, engine gauges or a radar. If a second station or radar is anywhere in your plans, pick a unit from a line built for it, like the Garmin GPSMAP series, Lowrance HDS PRO or Simrad NSS, and you will not be replacing the screen in two seasons. We stock radar and autopilot to grow the same network.
Do not forget the VHF
A chartplotter tells you where you are. A VHF radio is how you call for help, and offshore it is not optional equipment. Fixed-mount units with built-in GPS, like the ICOM M330G and ICOM M424G, send your position automatically with a distress call. The Lowrance Link-9 adds AIS receive, so you see commercial traffic on screen. Browse the full VHF radios category.
What is the difference between a fishfinder and a chartplotter?
A fishfinder uses a transducer to show what is under the boat: bottom, structure and fish. A chartplotter uses GPS to show where the boat is on a nautical chart. Most units sold today are combos that do both on one screen, which is why model names like GPSMAP or Elite FS cover both jobs.
What size fishfinder screen do I need?
Match the screen to the boat and to how far you sit from it. A 4 or 5 inch unit works on a skiff or jon boat, 7 inch is the sweet spot for most center consoles under 25 feet, 9 to 12 inch suits offshore boats where you split the screen between sonar and chart, and 16 inch displays are for helms that run several views at once.
Why do some fishfinders come without a transducer?
Because the transducer is a separate purchase decision. The same head unit can run different transducers, so brands sell the display alone for owners who already have a compatible transducer or want a specific one, and sell bundles with a transducer included for first installs. If this is your first unit, the bundle is usually the simpler buy.
Should I install marine electronics myself?
A single battery-powered fishfinder on a small boat is a reasonable owner project. Once the job involves cutting the console, running cables through the hull, mounting a transducer at the waterline or networking several devices over NMEA 2000, a professional install protects the boat and gets every feature actually working.
Marine Overhauling installs what it sells. Buying and installing with us saves you up to 15%: call (786) 277-2596 or request a free quote on our marine electronics installation page. We serve Pompano Beach, Fort Lauderdale, Miami and the greater South Florida area, and you can browse everything we stock by brand: Garmin, Lowrance, Simrad, Humminbird and Icom.