Furuno IF-NMEA2K2-8L Bi-Directional Converter for CSH8LMK2 Sonar

If you run a Furuno CSH8LMK2 scanning sonar and a TZtouch2 or TZtouch3 helm, this is the piece that makes them work as one system. The IF-NMEA2K2-8L is a premade, bi-directional converter that moves navigational data between your NMEA 2000 TZtouch network and the CSH8LMK2's NMEA 0183 data port. No adapter boards. No custom pinouts to chase down. The CSH8LMK2 NMEA0183 connector is already attached, so you're plugging into known ports instead of building your own harness.

Here's the problem it solves. Furuno's glass-bridge MFDs live on a NMEA 2000 backbone, and the CSH8LMK2 talks NMEA 0183 on its data port. Those are two different data languages. Without a translator sitting between them, your plotter and your sonar are basically strangers. This converter is that translator. It takes the position, heading, and course data flowing on the TZtouch network and hands it to the sonar, then carries data back the other way. Both directions, live at the same time.

Why does bi-directional matter? Because both boxes get smarter when they share. The sonar gets accurate heading and position from the TZtouch network, which keeps its 360 degree picture correctly oriented as the boat swings and drifts. And the plotter gets the marks and targets you generate on the sonar, so your chart reflects what the sonar is actually seeing under and around the hull. One-way data would give you half of that. This converter gives you both halves.

The CSH8LMK2 is Furuno's full-circle scanning sonar, the kind of omni sonar that paints a complete 360 degree picture of the water around the boat instead of just what's under the transducer. It's commercial-grade fish-finding, and it earns its keep on boats that live and die by finding schools first. But a sonar that capable deserves to talk to your chart. Out of the box, the two run on different standards, and that gap is exactly what this converter closes.

The real payoff is event marks. When you're watching a bait ball or a fish school light up on the CSH8LMK2's picture and you drop a mark, that mark carries over to your TZtouch plotter too. So the spot you found on sonar becomes a waypoint you can run back to, share across every display at the helm, and work again tomorrow morning. For commercial crews and serious sportfishermen chasing tuna or hunting bait, that hand-off from sonar to chart is the whole reason to wire the two together in the first place.

This is a specialized part, not a general-purpose gateway. It's built for one job, bridging a CSH8LMK2 to a TZtouch2 or TZtouch3 network, and it does that job cleanly. Because it ships premade with the sonar connector already terminated, most of the guesswork is gone before you start. We'd still tell you to plan the cable run, give it proper strain relief, and confirm your TZtouch software is current before you commission the system. A few minutes of prep up front saves you a headache later.

One note before you buy: this converter is model-specific. The 8L in the part number and the attached NMEA0183 connector are matched to the CSH8LMK2. If you're running a different Furuno sonar or a different display family, this isn't the right interface for that setup, and we're happy to help you find the one that is. But for a CSH8LMK2 feeding a TZtouch2 or TZtouch3 helm, the IF-NMEA2K2-8L is the part Furuno built for exactly this connection.

It's not a glamorous box. It's the quiet piece of the network that lets a top-tier scanning sonar and a top-tier plotter act like they were built to run together. Which, being Furuno, they were. If you've already invested in the CSH8LMK2 and a TZtouch helm, don't leave them talking past each other. This is the part that finishes the job.