Mar 5, 2015

Navico Broadband Radar and OpenCPN

N 28° 0.437', W 16° 39.626'

Our former radar was old but very reliable Furuno. The only problem with it was that the CRT screen was taking too much space and power. We didn't want any new screen either. We want to use a regular laptop or a tablet as a display for all navigational data. We are currently using OpenCPN as chartplotter, so it was interesting to find out that there is a radar plugin for OpenCPN. Navico Broadband radar has some interesting features like low power consumption and good visibility at close range. It seems like the perfect choice for us.

First view of the new radar. Our heading sersor still needs a bit of calibration.

We got the system working but there were some difficulties with installation.

My first mistake was that I didn't read carefully OpenCPN plugin documents before buying the radar. Navico 3G and 4G radars are sold under the brands Simrad, B&G and Lowrance. Our heading sensor uses NMEA 0183. By reading Navico documents I thought that Simrad 3G with RI11 interface was suitable for us and I ordered it. When I got the radar I read the plugin manuals through and found out, we didn't need any interface box at all. Lowrance 3G would have been cheaper, because it doesn't include an interface box. We chose 3G and not 4G because we don't need the longer range. Besides it costs more and uses more power.

Navico Broadband radar without interface box has radome and cable. Cable is an ethernet cable with additional power wires. It doesn't use PoE! When used with chartplotter like OpenCPN, it also needs heading and position data. OpenCPN plugin must provide this data to radar. Without position and heading there is no radar view! If you are using OpenCPN, you probably already have position data. We have an Airmar H2183 heading sensor with NMEA 0183 cable connected directly to our auto pilot. OpenCPN receives NMEA from serial port or ethernet. Our goal is to put all our NMEA data to ethernet, but now we made a temporary wiring for NMEA 0183.

Routing heading sensor data to OpenCPN was easy, but it didn't work. Plugin document states that used heading sentences are HDT, HDM or HDG. Airmar was sending HDG as default. I programmed Airmar to send HDT which it did, but without data. HDT means true heading. Sensor probably has variation database, but it needs position. Ok! I routed nmea position sentence (RMC or VTG) to Airmar and it started to send heading data.

We got a two second glimpse of radar picture in OpenCPN. OpenCPN was receiving gps and heading data through two different serial ports in our windows laptop. After a few seconds the other port died away.

Next step was to route heading sensor data through NAIS-400 AIS box. Now all NMEA input was in one serial port and it works.

We tested the new system by sailing at night from Las Palmas de Gran Canaria to Las Galletas, Tenerife. Radar targets and AIS targets were equal and we were very satisfied.

Installation would have been very easy by using a heading sensor with built-in GPS.