Monday, December 19, 2011

DMK Yacht Instruments

Application: iPhone, iPad, iPod Touch
Function: Marine data and instrument display
Rating: ****
Cost: App is free, black box is $399.00 or with GPS 499.00

There are many communication protocols out there when it comes to marine instruments.  Many of us have the older NMEA 0183, while others may have upgraded to NMEA 2000.  If you have Raymarine on board you are dealing with SeaTalk. Some may have all three onboard.  The problem has always been how do we tie all of these together to make them available to our laptops, iPhones and iPads.  DMK has built a system to address this very problem.

DMK Yacht Instruments has put together a versatile data display app for your iPad, iPhone or iPod touch.  The app uses the UDP protocol over WiFi to retreive the data from the DMK proprietary black box that must be purchased separately.

iPhone view
App features include:
  • iOS 4.2+
  • iPad, iPhone, iPod Touch
  • Apparent Wind Speed
  • Apparent Wind Angle
  • Boat Speed
  • Depth Below Transducer
Black Box features include:
  • Accepts any combination of Raymarine SeaTalk®, NMEA 0183, and NMEA 2000 inputs
  • Uses WiFi to send the sentences for each protocol as UDP packet payload
  • Two NMEA 0183 connections
    Separately configurable baud rates: 4800, 9600, 19200, 38400, 57600, 114200
Main Instrument View

  • One Raymarine SeaTalk® connection
  • One NMEA 2000 connection
Includes an RP-SMA Wi-Fi rubber duck antenna
  • FCC-approved Wi-Fi transmitter
  • Requires external power DC: 5-12v
Model 11A-GPS Only
  • Built-in 14-channel GPS
  • Includes an external passive GPS antenna which connects via threaded SMA socket
  • 0183 GPS Out; use this to provide location data to e.g. a Standard Horizon AIS radio


There are options to display the instrument by itself and change the options of the display. You can select digital or analog mode, fathoms, feet for meters for depth and options for Celsius of Fahrenheit for temperature.

These two screens allow you to manage logging and settings for the wireless network within the app.

I like that is has the flexibility to accept NMEA 0183, NMEA 2000 and SeaTalk protocols simultaneously.  This give you options if you have a mixture of different instrument types on your boat.  NMEA 2000 is the newest technology but there are still many of NMEA 0183 systems out there. If your a Raymarine fan SeaTalk is the protocol they use.

I don't like that the app only displays four instrument types.  Their webpage says that this is only a demonstration app. I assume DMK provides additional NMEA sentence support for other instruments.  DMK is selling the WiFi hardware for $399, or $499 if you want the GPS option.  iNavX is another app that can accept and display the data from the DMK box.  DMK uses port 1703 and UDP protocol. See the iNavX setup instructions here.  I assume other apps could be designed to access the data wirelessly through DMK's black box. Some apps allow the user to also use the iPhone or iPad's internal GPS for speed and location data. DMK's apps does not allow this.

There are cheaper options out there to connect your varied NMEA protocols to your iPad. Using the Actisense products to connect your NMEA 2000 or 0183 instruments to your laptop would be less expensive.  The laptop could then relay data via TCP/IP to an iPad app like iNavX or Mid +WiFi.

The Brookhouse iMux will connect your iPad or iPhone through WiFi to your NMEA 0183 and SeaTalk instruments.  There are lots of options our there. DMK has built a device to handle all the possible protocol options. Research which one fits your situation best and go with that. Hope this was helpful. What is everyone else using as a display app? Appreciate any feedback.


  1. Hi again Mark, I am just starting to ,make my way through your whole site here, and this particular article has caught my Eye.

    I guess everyone reading this site will have a different level of understanding of all this, but here is mine.

    I have a Yacht with an older "Stowe" NMEA 0183 basic Log Speed and Depth a system on board. I have added a basic NMEA 0183 Masthead Anemometer but now the depth transducer on the STOWE is playing up, and is a couple of hundred dollars to replace and only works with the STOWE databox.
    The paddlewheel of the log, continuously fouls up, and let's face it, who needs speed over water on a cruising boat anyway... SOG is what's getting you there. It would be nice to know SOW to tweak the speed out of the old girl, but the latest combined speed/depth/temp transducers with zero moving parts, still seem to be a million dollars each, so SOW is going on the back burner.

    This leaves then only Wind info and Depth, since the SOG and NAV functions are already built in to the I-thingy.

    The New SAILTIMERWIND hardware, would take care of the Wind info, but I would like to run this along side my existing fixed NMEA 0183 Wind instrument for Comparison.

    So I plan to completely remove the STOWE box and depth transducer, and replace the depth with an NMEA 0183 depth/temp transducer, possibly the CRUZPRO. I AM going to avoid RAYMARINE For obvious SEATALK reasons.
    I will leave the Current STOWE speed Tranducer BLANKING PLUG in place until an affordable wheelless SOW transducer becomes available.

    In summary then I need a multiplexer with a minimum of a two NMEA 0183 ports, one for wind, one for depth, the Imux is the first one that springs to mind.... BUT to allow for future expansion, an NMEA 2000 input would be invaluable.

    My understanding of NMEA 0183 v's 2000' is that 0183 works on a "spur" wiring arrangement, and therefore requires an NMEA 0183 port for each input, whereas NMEA 2000 works on a "daisy chain" wiring arrangement, and therefore will only ever require ONE port for Multiple sources....... Please feel free to confirm or deny if my understanding is correct.

    If it is, then this DMK looks like a good bit of hardware, but maybe the "Vespers Marine XB 8000 would be even better, allowing the addition of AIS at some future point too, but wayyy more expensive.

    So at this stage the DMK is winning in my book, my only concern is that this article was written in 2011...... Has anything better come along since??

    1. Mr. Yachty,

      I don't confess to be a multiplexer expert. I am more about the apps. I took a quick look at the DMK box and the Vesper XB8000. It appears the DMK is very versatile and will accept two 0183 signals, while the Vespers unit will only accept one.

      The DMK 11a will also handle any protocol out there including any Raymarine Seatalk devices. I think the Brookhouse iMux also has a version that will do Seatalk.

      It all depends on what you are wiring up. I like the DMK box looks like a good value at $400 compared to the $800 for the XB8000. I don't own either of these but would consider the DMK box because I own some Seatalk instruments and I am always looking for value.

      Let me know what you decide and how it works out for you!