What is NMEA 2000 and STng?
NMEA 2000 is a system, or ‘standard’ used for connecting marine devices so they can interact with, or ‘talk to’ each other. It uses the CAN (control area network) designed originally for the automotive market, but adapted for the marine industry.
The older version, NMEA
0183, allowed a GPS or chartplotter to send steering commands to the autopilot, for example, but this was a one-way street; one device talking and the other listening. Now, with NMEA 2000, digital signals can go in two directions simultaneously, with the result that each onboard device can talk to as many as 50 other devices.
The way this works is through a backbone cable running the length of the boat, with individual devices connected via spur cables. The backbone carries both data and power to attached devices. This reduces the complexity of the installation and means far fewer cables.
Under the NMEA standard, manufacturers can use the cable and connector design of their choice as long as it meets certain criteria. So, for example, you could opt for Raymarine’s SeaTalk 2, STng, Simrad Simnet and Furuno CAN – all rebranded versions of NMEA 2000.
Raymarine’s STng is what we’ll be using on Maximus. This means data from our AIS (originating from the VHF), wind direction and speed data (from the i70s and i60), and depth, speed and temperature (from the Analogue Tri Transducer) can be shared and shown on the Element 7 MFD along with its chartplotter functions – as well as link with instruments we might add in future.
As we’re starting from scratch we’ll be using Raymarine’s iTC-5 instrument to convert the analogue transducer signals from the wind, depth, rudder angle, etc. into digital STng data.
However, if you already had NMEA 2000 instruments on board from other brands, or Raymarine’s older version, SeaTalk 2, you can still connect them to each other using Raymarine’s DeviceNet cabling and connectors.
The Sailor radio
As you may have read in PBO’s letters pages, the vintage Sailor radio remains popular today, even though it’s at least 40 years old. Richard was delighted when he saw it. “You’ve got an old Sailor radio! You’ve got to keep that, right? You’ve got to keep it for nostalgic reasons.”
Richard’s not the first person to suggest I keep it. In fact his colleague, Greg Wells, has passed it on to his brother Rob, a radio enthusiast, who is fixing the Sailor radio right now. You can follow his progress on PBO’s YouTube channel. It’s looking hopeful…
If Rob can fix the Sailor we’ll have the small issue of running two VHF radios side by side – completely unnecessary, I know, but I don’t want to part with the beautiful Sailor! Modern radios just don’t have that same appeal.
“If it works you’ll have to have two separate VHF aerials,” advised Richard. “You couldn’t rely on one, and the two will need to be at least 1.5m apart so there’s no interference.”
Richard suggested we have one aerial on the back of the boat and another one at the top of the rig (our electrician recommended the Vtronix Hawk antenna).
We would need a splitter, but he pointed out that the AIS 700 transceiver has a built-in splitter so the cable will come from the aerial into the AIS unit and split back out to the VHF.
“You actually have most of the channels you would today on the Sailor VHF,” he pointed out. “However, by putting a more modern radio on you’ll have private channels added, and the DSC (digital selective calling) feature.”
DSC VHF radio
DSC is a definite bonus, allowing the radio to transfer information not just by voice, but digitally, sending an instant position and distress alert to the Coastguard.
That would certainly give me peace of mind when sailing with our three young children. “Push the red button,” is a much easier instruction than trying to explain how to do a Mayday, even though a followup voice call is still required. Hopefully we’ll never have to put it to the test.
We’re likely to go for the new Ray73 VHF radio with AIS and a loudhailer. With the GPS integrated into the VHF we don’t need the standalone Garmin GPS which is currently on board.
The built-in AIS receiver is another benefit. We’ll be sailing in the Solent shipping lanes and hopefully crossing the Channel one day so it would be good to use the AIS to keep a safe eye on ships, especially at night or in reduced visibility.
Richard also pointed out that with two sources of AIS, from the Ray73 and AIS 700, and GPS in both the Ray73 and Element MFD, there will be some issues needing data source selection.
We’ll be testing all these products on board Maximus so I’ll let you know how we get on. First things first though... it was time to meet the electrician and get his verdict on the wiring. At least now I had a better idea of what we wanted.
Watch Richard and Ali discussing electronics on PBO’s YouTube channel
‘The vintage Sailor radio remains popular, even though it’s 40 years old’