What Networkable Fish Finders Do

A networkable fish finder is a sonar unit that shares its screen data, GPS position, and sonar returns with other compatible devices on your boat — typically a second display unit, a tablet, or a smartphone running the manufacturer's app. Instead of buying two separate fish finders, you install one sonar transducer and one main unit, then add a second display or wireless receiver that mirrors what the primary unit sees in real time.

The network connection runs over Ethernet cable (hardwired between displays), WiFi (wireless within about 100 feet), or a combination of both. This setup is most useful on larger boats where the helm and the cabin are far apart, or when you want a second person to monitor sonar while you navigate. It also lets you run a smaller, cheaper secondary display instead of duplicating the full sonar package.

Key Takeaways

  • Networkable fish finders use one transducer and one sonar processor to feed data to multiple displays, saving money and installation space compared to two separate units.
  • Connection types include hardwired Ethernet (most reliable), WiFi (convenient but shorter range), or a combination depending on the brand and model.
  • Major manufacturers — Garmin, Lowrance, Humminbird, and Simrad — all offer networked systems, but compatibility between brands is rare; you must match displays to the same ecosystem.
  • Secondary displays range from full-featured touchscreen units to basic LCD screens or smartphone apps, and price varies widely based on features and screen size.
  • Networking adds cost upfront but reduces the expense of adding a second sonar view compared to installing a second complete fish finder system.

How the Network Connection Works

Most modern networkable fish finders use Ethernet over twisted-pair cable as the backbone. You run a single cable from the main sonar processor to a secondary display, and both units communicate at high speed with no lag. This is the most reliable method and works on boats of any size, though running cable through a cabin or across a large vessel requires planning during installation.

WiFi networking is the second option, available on many newer models from Garmin, Lowrance, and Humminbird. The main unit broadcasts a private WiFi network, and a tablet or smartphone running the manufacturer's app connects to it wirelessly. Range is typically 75 to 100 feet in open air, and performance degrades near metal structures or through multiple cabin walls. WiFi is convenient for temporary setups or when you do not want to run permanent cable, but it is not as stable as Ethernet during rough water or when the boat is moving fast.

Some systems use a hybrid approach: Ethernet between the main processor and a hardwired secondary display, plus WiFi to feed the same data to a tablet in the cabin. This gives you flexibility without sacrificing the primary connection's reliability.

Major Brands and Their Networking Standards

Garmin uses its NMEA 2000 and Garmin Network protocols. Their GPSMAP and echoMAP series can network to secondary displays or to tablets running the ActiveCaptain app. Garmin displays are generally the most affordable secondary option, and the ecosystem is well-established across their product line.

Lowrance (owned by Navico) networks through their Ethernet-based system and also supports WiFi on newer units. Their HDS Live and Elite FS series can feed to secondary displays or to smartphones via the Lowrance app. Lowrance tends to price secondary displays higher than Garmin but offers more advanced sonar processing on their main units.

Humminbird uses their proprietary network protocol, primarily Ethernet-based. Their HELIX and ONIX series can network to a second HELIX or ONIX display, and some models support WiFi to a smartphone app. Humminbird secondary displays are typically mid-range in price and offer good feature parity with the main unit.

Simrad (also Navico) networks similarly to Lowrance, using Ethernet and WiFi. Their NSS evo3 and GO series can network to secondary displays or tablets. Simrad is less common on smaller recreational boats but is standard on commercial and larger sport-fishing vessels.

Cross-brand networking is not standard. A Garmin fish finder will not network to a Lowrance display, and vice versa. You must commit to one manufacturer's ecosystem when you choose your primary unit.

Secondary Display Options and Costs

The type of secondary display you choose affects both price and functionality. A full-featured secondary display — such as a Garmin GPSMAP 8612xsv or Lowrance HDS Live — costs $2,000 to $4,000 and gives you all the same sonar views, mapping, and controls as the main unit. This is useful if two people need independent control or if you want identical capability at both helm and cabin stations.

A basic secondary display — like a Garmin GPSMAP 7410xsv or Humminbird HELIX 5 — costs $800 to $1,500 and shows sonar and GPS but with fewer advanced features or a smaller screen. These are ideal for monitoring sonar while someone else navigates, or for a second station where you do not need full control.

Smartphone and tablet apps are the cheapest option, often included free with the main unit or available for $20 to $50 as a one-time purchase. Apps like Garmin ActiveCaptain, Lowrance Insight Genesis, and Humminbird FishSmart let you view sonar and GPS on your existing device over WiFi. The trade-off is smaller screen size, shorter range, and no physical buttons — you control everything by touch.

Installation cost for a secondary display typically runs $300 to $800 depending on cable routing and whether you need new power and transducer connections. Smartphone apps require no installation beyond downloading.

When Networking Makes Sense

Networkable fish finders are most practical on boats longer than 30 feet, where the helm and cabin are far enough apart that a single display is inconvenient. A center console or open boat under 25 feet usually does not benefit from a second display, since one person can see the main unit from anywhere on deck.

Networking also makes sense if you fish with a crew and want one person monitoring sonar while another navigates. On a charter boat or a multi-angler setup, a second display at the rail or in the cabin lets your crew stay focused on fishing rather than asking the captain what the sonar shows.

If you are upgrading an existing fish finder, networking can be cheaper than installing a second complete sonar system. Adding a basic secondary display or a WiFi app to your current unit costs less than buying a second transducer, processor, and display from scratch.

Networking is less practical if you fish alone, run a small boat, or rarely need sonar data at more than one location. In those cases, a single high-quality display is simpler and more cost-effective.

Installation Considerations

Hardwired Ethernet networking requires running a cable from the main processor to the secondary display. On a new boat or during a major refit, this is straightforward — the cable runs through the cabin wall or under the deck. On an existing boat, you may need to drill holes, route cable through tight spaces, or use surface-mounted conduit. Plan the cable run before you buy the system, and budget extra time if your boat has a complex interior.

WiFi networking avoids cable runs but requires a clear line of sight between the main unit and the secondary device. Metal cabin structures, engine compartments, and fuel tanks block or weaken the signal. Test WiFi range on your boat before committing to it as your primary secondary connection.

Power requirements for a secondary display are modest — typically 5 to 15 amps at 12 volts — but you need a dedicated breaker and properly sized wire. If you are adding a hardwired secondary display, have a marine electrician size the power circuit and install it to ABYC standards.

Transducer and Sonar Processor Compatibility

Networkable fish finders use a single transducer (or occasionally two, for different frequencies) connected to one main sonar processor. All displays, whether hardwired or wireless, receive data from that one processor. This means you cannot have different sonar views on different displays — they all show the same frequency, the same zoom level, and the same chart overlay unless you manually adjust each display independently.

Some systems allow you to control the sonar from either display, so the person at the secondary station can change frequency, adjust sensitivity, or zoom the view without affecting what the helm sees. Others lock control to the main display only. Check the manufacturer's specs before you buy, especially if you want crew to adjust sonar settings from a secondary location.

Transducer quality matters more in a networked system because you are relying on one transducer for all your sonar data. A high-quality transducer with multiple frequencies (typically 50 kHz, 83 kHz, and 200 kHz) gives you flexibility and better performance across different water depths and conditions. Budget $300 to $800 for a good transducer, depending on the type and frequency range.

Frequently Asked Questions

Can I add a WiFi app to my existing fish finder?

Many newer fish finders support WiFi apps without any hardware changes. Check your unit's model year and software version — Garmin, Lowrance, and Humminbird have all added WiFi capability to recent models through software updates. Older units may not support it, even if the manufacturer offers an app for newer models.

What is the range of WiFi networking on a fish finder?

WiFi range is typically 75 to 100 feet in open air, but metal structures, cabin walls, and engine compartments reduce it significantly. On a boat with a metal cabin, you may only get 30 to 50 feet of reliable range. Test your boat's specific layout before relying on WiFi as your primary secondary connection.

Do I need a second transducer for a secondary display?

No. Networkable systems use one transducer and one sonar processor to feed all displays. Adding a second display does not require a second transducer. Some advanced systems allow you to add a second transducer for a different frequency or viewing angle, but that is optional and adds cost.

Can I use a secondary display from a different brand?

No. Fish finder brands do not network across manufacturers. A Garmin main unit will only network to Garmin secondary displays or Garmin apps. Lowrance, Humminbird, and Simrad each use their own proprietary protocols. Choose your secondary display from the same brand as your main unit.

What happens if the secondary display loses connection?

The main display continues to work normally. If you lose WiFi connection, the app or secondary display goes blank until the connection is restored. If you lose an Ethernet connection, the secondary display typically shows an error message. The sonar processor and main display are unaffected — you still have full sonar capability at the helm.