Gromit Gets an Electronics Upgrade

When we bought our boat, we knew something needed to be done about the electronics.  It’s a pretty good lineup and completely functional, but dated.  This is what we have:

  • Nexus Start Pack 3 wind/depth/speed (2014)
  • Furuno VX2 chartplotter with radar (2008)
  • Comnav Autopilot (2008)
  • ACR Nauticast AIS (2009)
  • ACR EPIRB (2009)

Here are some of the issues we’ve had with the current setup:

  1. The charplotter runs on 2GB chart cards, which are difficult to find and quite a bit more expensive than the newer chart cards.  They cover smaller regions so you have to buy more of them vs the newer chart plotters.  The boat did not come with any cards, so if we wind up doing a circumnavigation, we’d end up spending many thousands of dollars on chart cards.  The plotter still functions as is for displaying AIS data, and radar, but it is overlaid on a very crude chart with no details of buoys or landmarks.
  2. The EPIRB is functioning but expired, and the registration details are for the previous owners.  EPIRB stands for Emergency Positioning Radio Beacon.  In a nutshell, if something goes wrong and we need help, we press a button and it notifies the authorities via satellite and radio transmission, sending them our GPS coordinates.  An essential piece of equipment to have on board!
  3. The AIS is transmitting the wrong MMSI number.  An MMSI number is a unique number that represents our boat.  The AIS transponder transmits data about our boat, including the MMSI number, GPS position and heading data to other boats in the area.  It also receives data about other boats and displays it on a map.  Since the boat was Canadian registered, the MMSI number was Canadian and could not be transferred to us; we had to apply for a new MMSI number from the FCC.  It can be reprogrammed by the manufacturer, but they did not respond to our emails (thanks ACR!)
Without a chart card, the plotter thinks we are on dry land!

So, replacing the EPIRB is a no brainer. The new EPIRB’s have longer service lives (10 years vs 5 years) and are user serviceable (the one we have on the boat requires you send it to a service center to get the battery replaced… uh… no!)


On the chart plotter, I felt we had three options to move forward:

  1. Keep the chart plotter and buy the cards, the cost on this is north of $2800 for a circumnavigation, plus the cards are difficult to source.
  2. Buy a new chart plotter and radar.  This route would also require buying chart cards in addition to the equipment, but at least we’d have new state of the art equipment that can run the newer chart cards.  Cost $3k+ for the gear, another $2k for the cards.
  3. Scrap the chart plotter idea altogether, and navigate using iPad and a laptop.  Equipment is free (we already own), charts are $50-100 each and cover relatively large regions.  This is the lowest cost option and the one we chose.  With the money we saved on the the cards/equipment, we decided to install an NMEA2000 cabling system that would allow the laptop and iPad to see instrument data from our GPS, depth, wind and compass.

NMEA2000 is a network protocol where all instruments get their power from, and send their data through a single communications “trunk line”.  This means you can plug a device in anywhere in the network and it can see and use data from other instruments.  It’s simple and efficient.  Here’s what we bought:

  • Garmin GND10 ($171)  – This translates between the language our Nexus Start Pack speaks and NMEA2000, and was cheaper than buying NMEA2000 instruments.
  • B&G ZG100 External GPS w/built in compass ($199) – This will feed GPS and compass data to the iPad and OpenCPN (PC).  Technically the Comnav autopilot will also feed compass data to the network, but having this keeps us from having to run the autopilot for compass data, especially useful at anchor or when using our wind vane for steering.
  • Vesper XB-8000 AIS Transponder ($686) – Ouch!  This was the big one, but it will take in all of our NMEA2000 and NMEA0183 data and broadcast the output via USB and WiFi.

The large items and all of the related cabling: $1280.

At the same time we also bought:

  • ACR GlobalFix v4 EPIRB ($399) – has a 10 year service life, and user replaceable battery!  We’re going to keep the old one, as a backup.
  • Balmar External Voltage Regulator ($432) – Not navigation related.  We were having issues with our alternator either putting out too much or too little voltage. This will hook up to the alternator on the engine and regulate it a lot better than the internal regulator does, hopefully extending the life of our battery bank (which is very expensive to replace!)

“Hey you must be rich!”  Not really.  This is a pretty modest budget for an electronics upgrade, some folks spend $10’s of thousands of dollars!  In fact, this upgrade allows us to reliably use our existing iPad and laptop for navigation, and was cheaper than buying new cards for, or replacing, the existing chartplotter!  This was also part of the “start up” budget which had already been planned.

The girls helped with the unboxing.

Despite the small-ish budget, a project like this takes careful planning.  All of the wiring needs to be special ordered to length, so I had to pre-plan where all of the components would sit and take careful measurements on the boat.  That being said, things never go to plan and adjustments had to be made as I was installing.  For example, I had planned to have the GND10 in the bow of the boat, but instead mounted it in the Nav station.  I found a cable on board (from the previous owner) that allowed me to do this, saving us a few bucks as we were able to return the cable we bought.

The existing equipment (black) and new equipment (blue).
I added a couple of wires to power the network… see the red one?
The Nexus black box and power junction for the new network under the nav station.

While the new wiring spans the entire length of the boat, most of the work took place on the stern, where I had to remove the existing AIS and AIS antenna, then add the new AIS, AIS antenna, GPS/Compass antenna and fabricate a bracket.  All of the antennas sit on the davits with the wiring run through the lazarette, which meant emptying all of the contents onto the deck.  I hate having messes on the boat, and this one persisted for almost a week!

That’s me in there, good times!
Cozy in the aft lazarette, it wasn’t worth it to take the spare anchor out.
At least it was big enough to comfortably run the wiring!
Marlee supervising to make sure I’m doing it right.
Try to keep the wires tidy and out of the way – to prevent snags when pulling items out of the lazarette.
GPS and AIS antennas on a bracket I made (the picture is strategically angled to hide my inability to cut a straight line).
AIS in the aft cabin, this keeps the length of the VHF antenna cable short, which reduces RF interference.

And the result is, somewhat anticlimactically, shown below!

iNavx on the iPad showing AIS targets and heading information, all via WiFi!
OpenCPN showing AIS and instrument data!

I contemplated our options for a really long time (like 5 months) before we pulled the trigger on this, debating whether to buy cards, a new chart plotter, or go with the system we implemented above.  This system gives us the most bang for the buck, and gives us flexibility in the future should we choose to add more components, I suppose you could say it was the “wise” path.

But also this gives us another layer of redundancy.  These days we are so dependent on GPS to navigate – we now have more GPS devices on board in case one fails.

The new EPIRB sits in its cradle next to the old one.  In an emergency we’d grab the new one first, both of them if we have time.  The older one still works, for now.

EPIRB under the companionway steps.  And the the shoe basket, very important.