Wiring the Instruments on a Catalina 320

We are getting close to finishing the update to our wiring on our 1994 Catalina 320 Achernar. As the boat came, it had the original Raymarine depth, wind, speed, and autopilot devices at the binnacle. It also came with an approximately ten-year-old AIS, antenna splitter, AM/FM radio, and chart plotter, as well as an ancient VHF radio, and Garmin radar dome on the mast. The chart plotter supports NMEA 2000, but the AIS only supports NMEA 0183 (see the other posts we have done about these technologies). The NMEA 2000 network on the boat only had three drops: 12V in, a Garmin 17X GPS antenna, and the Garmin 4212 chart plotter. The chart plotter showed radar and GPS, but none of the info from the devices at the binnacle, nor the AIS info. The AIS broadcasted the info about the location of our boat, but didn't have any way to show the location of any other boats.

Our goals:

  • A VHF radio that supports DSC
  • A VHF remote handset accessible from the cockpit
  • A chart plotter showing depth, wind, speed, autopilot, and AIS info
  • Saillogger recording the info on our travels with a reliable Internet connection
  • Replace as few of the instruments and devices as possible

Eventually, we'd like to replace all the instruments and devices with state-of-the-art equipment. But this will take a considerable amount of time and we'd rather be out cruising.

Since the VHF radio didn't support DSC, that required a replacement. We consider DSC to be a critical safety system on the boat as it provides a panic button that alerts the Coast Guard to our exact location should we run into problems. We replaced the VHF with a new Standard Horizon GX6000 (in retrospect, we could have gone with a cheaper radio and still met our goals). We also acquired the RAM4 wired remote microphone. We considered the wireless remote microphone, but the reviews we read said that the wireless version was unreliable. Unfortunately, the squelch on the radio failed shortly after we installed it, causing the radio to blast static at full volume. We had to send it in for warranty repair, which required almost six weeks to turn around, plus the cost of shipping it to them.

We ran new wires between the "garage" (the large locker on the port side of the Catalina 320) and the panel to the right of the chart table in the cabin. The two wires we ran were a NMEA 2000 backbone cable and the cable to support the RAM4 microphone. There is a channel for wires that runs across the top behind the galley cabinets. We opened the panel on the right side of the top right cabinet that allowed a fish tape to be extended from the electrical panel, through the channel, to the garage. This made fishing the new cables relatively easy. There is lots of room for cables in the channel.

Wires run under the pedestal in the aft cabin

In the garage, we added two blocks that provide the connection of the NMEA 2000 backbone to the devices at the binnacle. The ST60+ depth, ST 30 wind, ST 30 speed, and ST4000+ autopilot were all connected to each other with a SeaTalk1 network. However, the network did not extend anywhere else. We ran a new SeaTalk1 cable from the garage to the port aft lazarette, then under the pedestal in the aft cabin and up the stanchion to the devices. This required taking off the cover from under the pedestal in the aft cabin, which was held in place with bunch of screws. We removed two cables that ran up to the instrument panel: an obsolete and unused depth cable and a power cable. This freed space inside the port-side stainless steel pedestal support stanchion. We pulled the SeaTalk1 cable by taping it to one of the cables we were removing. We had to cut the SeaTalk1 cable to pull it, then splice the cable back together because the cable end was too large to fit down the stanchion. Because the SeaTalk1 cable provides power, we no longer needed the separate power cable and removed it.

The SeaTalk1 cable is attached to a small block that just allows another SeaTalk1 cable to be plugged in. That then connects to the SeaTalk1 to SeaTalk NG Converter. This block converts SeaTalk1 to SeaTalk NG (which is the same protocol as NMEA 2000, but with proprietary connectors). This then has a cable that has a SeaTalk NG connector on one end and NMEA 2000 connector on the other. This connects to the NMEA 2000 backbone. As soon as this was connected, the chart plotter started showing wind speed, wind direction, and depth. This info was also passed to saillogger, so shows up on the monitor page.

Achernar Wiring Block Diagram

The other end of the NMEA 2000 backbone runs into the cabin. This is connected to the Standard Horizon GX6000 VHF. Although the radio has an AIS receiver (but not transmitter) built in, we are not using it, instead using the West Marine AIS 1000 transceiver that came with the boat. (For the last five years Standard Horizon has described a GX6500 model that has an AIS transceiver built in, but the rumor is they have had trouble getting it certified by the FCC.) While we could receive AIS on the GX6000 and transmit with the AIS 1000, we run into a little problem with the antenna.

On a sloop sail boat, you only have one mast, but you need two antennas: one for VHF transmissions and one for AIS transmissions. They need to be separated by several feet. On a power boat, you can just fix two antennas to the top of the cabin in different places. On a sail boat, the workaround is something called an antenna splitter. You put up one antenna, but plug the VHF and the AIS into the antenna splitter and connect that to the antenna. (It can also handle AM/FM.) VHF is considered a safety system. If you push the DSC panic button, you cannot have the AIS transmitting, so when the VHF is being used, the splitter gives it priority. But if you have two AIS units, you will need two splitters, which would theoretically work, but asking for trouble. (Why the GX6000 doesn't have an antenna splitter built-in is a mystery.)

Instead, we just ignored the fact that the radio has an AIS receiver and used the West Marine AIS 1000 transceiver that came with the boat. That came with its own can of worms, the first of which was that we changed the MMSI associated with the boat. The MMSI that came with the boat was likely issued by BoatUS or the US Power Squadron. These free numbers only work in the United States. We plan on going to Canada on our boat, so the MMSI needs to be issued by the FCC. An FCC MMSI (which you can identify because it ends in zero) is exchanged with other countries, including Canada. This allows you to push the DSC panic button in Canadian waters and the Canadian Coast Guard will come rescue you. We applied for and received our new MMSI.

However, the FCC does not let end users of electronic equipment arbitrarily change the MMSI on equipment. Our new radio lets you put the number in once, but you have to send it back to Standard Horizon to change it thereafter. Our West Marine AIS already had a MMSI inputted, so it could not be changed. We contacted West Marine, but of course they are not the manufacturer, no longer sell it, and don’t really support it any more. West Marine emailed back some minimally helpful information that eventually led to getting it changed.

The wiring in the garage. Not as beautiful as we would like, but better than it was.

The next challenge was that for the chart plotter to get the AIS info. We needed the AIS to be on the NMEA 2000 network. That is all well and good, except the AIS 1000 only does NMEA 0183. We bought a Digital Yachts iKonvert unit that converts 0183 to 2000. While relatively expensive, it still was much cheaper than buying a new NMEA 2000 compatible AIS transceiver. The iKonvert little box has a NMEA 0183 connector on one side and a NMEA 2000 connector on the other. There are also DIP switches that control what messages should get passed through and the speed of the connection, which we set to AIS and GPS transmitting at 38400 baud. As soon as it was connected, the AIS info from other boats started showing on the chart plotter. A friend confirmed that we were transmitting our location, but that was always working.

But then a new problem started happening: The chart plotter was getting GPS info unreliably. The AIS 1000 has its own GPS antenna, separate from the one on NMEA 2000 network. The iKonvert was passing GPS info through from the AIS 1000 to the NMEA 2000 network, and the Garmin 4212 chart plotter was prioritizing the AIS 1000 GPS info. For whatever reason, this info was coming through intermittently and causing an error. We finally found the setting in the chart plotter to prioritize the Garmin X17 GPS antenna, which solved the problem.

We mounted the external connection for the RAM4 microphone on the port side, just below the propane locker. The boat came with about an inch diameter of broken fiberglass at exactly this spot which needed to be repaired, so drilling it out solved two problems. The one drawback to this location is that the aft locker door will run into the microphone if it is fully opened. So we will be attaching a cable to limit the distance the door will open by a couple of inches.

The last thing we needed was for the Raspberry Pi that saillogger runs on to have a reliable Internet connection. For that we acquired a Galaxy pad A7 Lite with a SIM card from T-Mobile. This runs a wi-fi hotspot that the Pi connects to. The monthly cost is relatively cheap, and the device was free after paying tax and a connection charge.

All of the equipment is now connected and working. Our next step is to make it all pretty, but that’s a topic for another day.


Don't Use 5200 On Your Boat

This is going to be a rant about 3M Marine Adhesive Sealant 5200 and why you shouldn't use it on your boat. If you are not a boat builder, you have no reason to use it. The problem is that 5200 creates a permanent bond between two surfaces. There is that word "permanent". What, exactly, is permanent on a boat? Is a port-light permanent? Or a winch? How about combing? A stanchion? A bow roller? None of these are permanent. All of them will need to be serviced and replaced at some point. It might be 10 years, or it might be 20. If you use 5200, you, or the person who eventually owns your boat, will swear at that idiot who used 5200.

Okay, there are a few reasons to use 5200. If you are putting a new thru-hull below the waterline, that might be a reason. I think we used 5200 to fasten down the mast step on our Catalina 22 that was loose because that has a seriously long lever trying to pry it up from the deck. But almost anything that you think you should 5200 for could also be done with 4200 or even 4000.

Some people will use debonding agents, or have a scheme with a guitar E string for getting 5200 separated. But why do that when you could have used 4200.

Captain Boomies did a cool demo on why 5200 is the wrong product for anything you can think of on a boat. When you think of something that you might want to use 5200 on, ask yourself "can I use 4200 or even 4000 for that thing".