Garmin MSC 10 installed and testing underway

Ben Stein

Ben Stein

Publisher of, passionate marine electronics enthusiast, 100-ton USCG master.

17 Responses

  1. Donald Joyce says:

    Garmin is certainly in the lead providing dual band GPS receivers for the marine market. It would be great for Furuno, Navico, and Raymarine to follow

    • Wolfgang Jansen says:

      IIRC dual band is used mainly to overcome multipath errors. Especially usefull in cities, less so in open spaces. Obviously the accuracy is better with dual or triple band receivers.

      Would be nice to see a comparison with the SCX20, because Furuno claims their 4 receivers also reduce multipath errors.

      @Ben, the SCX20 has a magnetic sensor, according the manual. I do not know what it does, I assume it is used for the dead reckoning.

      • Andy says:

        Actually dual band is mainly used to cancel out the ionospheric error. Anti-multipath is a nice bonus.

        • Wolfgang Jansen says:

          Hi Andy,
          Thanks, you are right.
          I had this information from a test with Garmin hand-held receivers.
          But they were wrong in their conclusion.

  2. I am sure there is a reason why Furuno gives the maximum accuracy of the SCX-20 as 3 meters. However, after a year of using one, my experience is that it appears to do better. My slip is about 3.5 meters between the pilings and my SCX-20 is mounted dead center on the boat. On a repeatable basis, the SCX-20 shows me in the same spot within a foot or two. If I compare that to the position output from the internal GPS sensor in the Furuno TZT 3 MFDs, which will often show the boat a bit to one side or the other in the slip, the accuracy advantage of the SCX-20 is very apparent.

    My observation is that Garmin is somewhat more aggressive in putting forward marketing claims that the rather conservative Furuno engineers. It doesn’t make a lot of sense that triangulating position from two GNSS sensors in the Garmin MSC10 would be inherently more accurate than the four sensors in the SCX-20.

    I note that Simrad also claims 0.3m position accuracy for its HS75 satellite compass. Maybe you could reach out to your contacts at Furuno for an explanation of why the SCX-20 is specified at 1 meter while the competition claims greater accuracy.

    • Wolfgang Jansen says:

      I have the SCX-20 now for about 6 months in use. In Timezero it shows an accuracy of 0,78m. I do no know how this is calculated, but the ship’s docked position on the chart (Navionics vector based) is spot on and virtually does not move when moored.

      I am also wondering why dual band GPS should do better than single band, multipath excluded. Because this topic is new for me, I checked it to see what it is. Appearantly the only difference is the stronger L5 signal, but coming from the same (okay, replaced by newer types) GPS satellites. The whole basic of GPS satellite positioning calculation is unchanged, no additional satellites are added. The more satellites in the correct angle to each other and the receiver, and less atmosferic disurbances, the better the position calculation (accuracy).
      Some tests of handheld Garmin receivers (for hiking) I read about, are showing quicker first position fixing time and much better accuracy (less deviations due to multipath) in the city. In open space (forest in this case), accuracy differences (deviations) were minimal (due to absense of multipath errors).

      • Donald Joyce says:

        Dear Wolfgang,
        I interacted with the TZ support staff regarding the GPS accuracy being displayed when I first noticed that the GPS input I was using at the same time showed a much more conservative accuracy and I was left with the impression that TZ would eventually revisit their calculation.
        Second, while it is true that the L1 and L5 signals come from the same sattelite, it is also tru that the frequencies are not the same. One can use the frequency difference as a venier to improve the position accuracy as well as more accurately correct for atmospheric distortion. That’s why the US military has used dual frequency since the inception of GPS. The same reason position sensitive farming equipment as well as land survey equipment had used dual frequency for some time. The delay in its availability to the marine market has simply been cost vs perceived need. At the moment, very few marine charts, if any, are accurate enough to where one would be sensitive to the accuracy available from dual frequency GPS. Having said that, I still want one. Sigh.

        • Wolfgang Jansen says:

          Hi Donald,
          the SCX-20 replaced the GP-70 from Furuno (which was a replacement for the Decca nevigation system, we had a Philips Ap Navigator
          Anyway, that time (eighties) I wanted to know how GPS works. L1 had a selective availability (i.e. U.S. Government could set the accuracy at will), and L2 was/is encrypted (for military use). About 15-20 meters was the best you could get. Until the Gulf war, where the military had to use commercial systems (partly) and selective availability was set to 0 / shut off.
          Long story short, nowadays GPS (without atmospheric distortion) has an accuracy of about 0,7m (see URE). Indeed the atmospheric conditions can be partly eliminated using multiple frequenties (L1, L2, L5), multipath can be eliminated if the stronger L5 signal can travel trough the obstructions, otherwise not. Accuracy is further improved with WAAS and by multiple stationairy readings (averaging to get into the cm or even mm range).
          You are right regarding the marine charts and need for dual frequenty GPS in the marine world.
          Maybe the multi GNSS still is the better option for marine use, there are 4 (and if the British do what they want to do, in the future maybe 5) different GNSS systems available and theoretically you can mix all the satellites in your position computation, getting the best results.

          • Andy says:

            A “stronger” signal has little benefit regarding the multipath. It happens regardless of the signal power.

            There are various ways to combat multipath, from classic ground plane choke ring survey type antennas to more modern digital beamforming, and of course extensive signal processing, But signal strenght alone has a little to do with this.

      • Andy says:

        Dual band is mainly used to cancel out the ionospheric error, one of the biggest sources for GNSS. Also L5 signal is much more modern than “ancient” L1, plus being stronger, so there is substantially stronger correlation confidence for that signal increasing the accuracy, plus much more controlled band (L5) thus less interference.

        Anti-multipath is a nice bonus.

  3. Bob Easterday says:

    I’d be interested to hear about what affect this has on the sonar display. Specifically, do Garmin MFDs compensate for roll and pitch as provided by the MSC-10

  4. Chris says:

    Very excited to see your full review of the MSC-10 as I’ve been anticipating this product for a while. I’m curious if the back up magnetic compass is needed if I already have the 9 axis heading sensor. Can a back up compass be selected in a configuration screen if one exists on the network?

    • Enric says:

      I believe there’s no difference, it’s always giving heading, but with moreless precision. Also, when you start, is already giving a heading, that will have more precision as long as it improves GPS position

  5. UH says:

    The installation position of the sonar sensor and the sat compass differ. In big boats by some meters. So this difference and the movement of the boat itself has to be taken into account for a proper compensation. How is this done?

    • With the Furuno hardware, the positions of the transducer and satellite compass on the boat are entered into the settings to support the heaving compensation and pitch and roll data. It works very well. Over a flat seabed, you can be in 6 foot seas and the sounder shows the bottom as a straight line with constant depth readings. Before I had the satellite compass and the heaving compensation, the bottom would have been wavy and the depth reading would have been bouncing up and down with the waves.

  6. Sven says:

    Any updated thoughts from Ben and the field on Sat compasses? Looking at a Raymarine install and trying to decide between MSC10 and SCX20 unless Raymarine brings a satellite compass to market – and understand how much it would give us above the AR200.

    Current Garmin setup is running on a Steadycast, so all are likely an upgrade.

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