Airmax Smart Tri (DST800) transducer issue

[mnbuarque]

Hi Cruisers,
I just cleaned the transducer of my boat (an Airmax Smart Tri, I suppose that is a DST800) and I was aiming to calibrate the speed.
However, I noticed that, despite showing depth, speed, and water temp information, all instruments are not able to "find" the transducer in order to enable me to calibrate that.

I also noticed that sea temp is quite low (15C ) considering the temperature I can feel (23C at least)

Do you believe the transducer is presenting a failure? Even being able to provide to SeatalkNG the information about speed (demanding calibration), depht (100% ok) , and sea temperature (looks like uncalibrated) ?

BR
Marcelo

[tanglewood]

In my experience with a number of these, the temp always fails, the speed never works in the first place or can't be calibrated to work. but depth keeps working. So I only expect it to be a D800 (depth only), am pleasantly surprised when it's a DT800 (depth and temp), and never waste money on a DST800 (depth, speed, temp).

[jordanbigel]

Temp on my DST800 stopped working after 6 months. Speed and depth still work. I heard that it is very easy to damage the temperature sensor even with a stuff plastic brush. Disappointing, and if I knew of a reliable tri-ducer I would switch.

[mnbuarque]

Originally Posted by jordanbigel

Temp on my DST800 stopped working after 6 months. Speed and depth still work. I heard that it is very easy to damage the temperature sensor even with a stuff plastic brush. Disappointing, and if I knew of a reliable tri-ducer I would switch.

Well... being already prepared to conclude I have a HW fault, if anyone has a better transducer to recommend, I would be thankful for a recommendation! (preferably one I can connect in a SeatalkNG or NMEA200, and onde that fits in the same "hole") . Reliable depth and Speed is more than enough.

[derfy]

Originally Posted by mnbuarque

Hi Cruisers,
I just cleaned the transducer of my boat (an Airmax Smart Tri, I suppose that is a DST800) and I was aiming to calibrate the speed.
However, I noticed that, despite showing depth, speed, and water temp information, all instruments are not able to "find" the transducer in order to enable me to calibrate that.
I also noticed that sea temp is quite low (15C ) considering the temperature I can feel (23C at least)

Do you believe the transducer is presenting a failure? Even being able to provide to SeatalkNG the information about speed (demanding calibration), depht (100% ok) , and sea temperature (looks like uncalibrated) ?

BR
Marcelo

The DST800 connects to your SeaTalk or NMEA2000 network thru an A-to-D (analog to digital) converter "pod" which receives analog signals from the wires on the transducer, and converts the analog signals into digital packet data for the STng or N2K (for example, a Raymarine iTC-5). If you cannot "see" this A-to-D device on your network as a Device on the network, using the network menu on your MFD (Multi-function Display - such the small one dedicated to Wind and Depth, or a larger Chartplotter MFD ), then the problem is with your network connectivity, or the A-to-D "pod". If you can see it, but the readings are all bad values (ie 0 or stuck at one constant value), the problem is with the transducer or wiring.

I installed a new DST800 a few weeks ago and the speed just recently quit. I pulled the transducer from the tube (a little scary, but, okay, it works), and it was just slightly fouled with algae - no barnacles.

I am now cleaning it up and preparing to paint it with special transducer anti-fouling paint (MDR-720). What a PITA that will be. Surface-prepping and brushing on hard to reach nooks and crannies without screwing up the free motion of the paddle wheel. What rocket scientist invented this thing and forgot to simply apply the anti-fouling coating to the manufactured product?

I regret now not having a separate Depth transducer from a Speed Transducer (ie different thru hulls). The depth does not foul out very often and is the most important function. I could just leave it in place and not have to keep pulling and cleaning it.

The speed-thru-the-water is useful to know if you are in foul or fair current (comparing it with GPS SOG) and to get a True Wind Speed and Angle (sometimes useful in looking for a place to raise or drop sails in tight winding channel, but it is not a critical metric). Calibration of Speed is also a PITA.

[mnbuarque]

Originally Posted by derfy

The DST800 connects to your SeaTalk or NMEA2000 network thru an A-to-D (analog to digital) converter "pod" which receives analog signals from the wires on the transducer, and converts the analog signals into digital packet data for the STng or N2K (for example, a Raymarine iTC-5). If you cannot "see" this A-to-D device on your network as a Device on the network, using the network menu on your MFD (Multi-function Display - such the small one dedicated to Wind and Depth, or a larger Chartplotter MFD ), then the problem is with your network connectivity, or the A-to-D "pod". If you can see it, but the readings are all bad values (ie 0 or stuck at one constant value), the problem is with the transducer or wiring.

I installed a new DST800 a few weeks ago and the speed just recently quit. I pulled the transducer from the tube (a little scary, but, okay, it works), and it was just slightly fouled with algae - no barnacles.

I am now cleaning it up and preparing to paint it with special transducer anti-fouling paint (MDR-720). What a PITA that will be. Surface-prepping and brushing on hard to reach nooks and crannies without screwing up the free motion of the paddle wheel. What rocket scientist invented this thing and forgot to simply apply the anti-fouling coating to the manufactured product?

I regret now not having a separate Depth transducer from a Speed Transducer (ie different thru hulls). The depth does not foul out very often and is the most important function. I could just leave it in place and not have to keep pulling and cleaning it.

The speed-thru-the-water is useful to know if you are in foul or fair current (comparing it with GPS SOG) and to get a True Wind Speed and Angle (sometimes useful in looking for a place to raise or drop sails in tight winding channel, but it is not a critical metric). Calibration of Speed is also a PITA.

Hi, My transducer does not have an additional A/D converter. I have a SeatalkNG cable directly from the transducer (as in the picture I attached).

[derfy]

Originally Posted by mnbuarque

Hi, My transducer does not have an additional A/D converter. I have a SeatalkNG cable directly from the transducer (as in the picture I attached).

Yes, okay. I used to have one like that. AtoD and network interface is built in to the transducer.


So if you cannot detect this device on your STng/N2K network (from the MFD), then either the device is dead (not likely if it is new), or the network connection is not properly working.



I would examine the network. You will physically need to trace out how the DST is connected back to the Backbone and the MFD. Does your MFD work and detect other devices (ie wind instruments, auto pilot, etc)? Is the network backbone terminated on each end? Do you have 12v power to the network? This DST will get its power from the network, I think.

[OldGreyB]

Mnbuarque, you do not state what actual model devices you have on your SeatalkNG network. It would be helpful if you posted that information. However, generically sometimes a specific device connected to the network will not "allow" the Raymarine display device seeing the Airmar or other transducer to calibrate, even if Raymarine device display is reading the NMEA sentences.

You should have a network diagram, and know where each device is connected. I suggest you should temporarily unplug the SeatalkNG spur cable to your Auto helm and any spurs to secondary SeatalkNG Raymarine device displays (ST70 or similar devices), so you end up with only one connected SeatalkNG Raymarine device display , and your MDF connected. Caution do ensure the main backbone is still fully connected and functional with end terminations at this point.

Then apply the "Search for transducers' on the connected SeatalkNG Raymarine display unit. If you are lucky, you will see the "Search Results" show depth / speed / temps, drill down to their appropriate calibration pages and calibrate on the display unit.

[mnbuarque]

Hi everyone,
Using a lot of the knowledge you shared with me, I have dissected my network and tested all devices, one by one. Checking what one was creating the problem.
I will share the main conclusions because it can be useful for someone.

1- I am posting the full network map I made for the boat. And I passed thru all connectors and hubs, cleaning them one by one to eliminate any possibility that could blur further the tests.
2- To reduce the "test environment" I shortened the Network to get focused on a cluster of suspect equipment. This shortened network is also attached.
3- At the very beginning of the tests I noticed something important: In the "Search Results" screen (shared above by #OldGreyB), the transducer DST800 was appearing immediately after turning the network on, and disappeared 2 or 3min later. My conclusion: data from some equipment, spitted in the network some minutes after turning the network on was creating the problem.
4- After disconnecting equipment one by one (and turning the network off and on for each one), I identified the GPS Raymarine RS130 as the "guilty" (despite having all positioning information being fine in the network). Once disconnected the RS130, the transducer DST800 keeps listed in the Search Results for good.
And, as a counterproof, keeping the network on, connecting RS130 was making DST800 disappear, and disconnecting was making DST800 reappear.

Now, I will make the final test to get a verdict and decide if I will replace the GPS :
I will get an RS150 lent and place that in the network to check if the problem gets vanished. And, at the same time, I will place my RS130 in another network to check if that causes the same issue there.

So....seatalkNG remains a challenge. A functional GPS can create a glitch that makes a DST800 transducer disappear from calibration options (search results list) despite perfectly providing depth, Speed, and Temperature to the network. Crazy!

I hope the diagrams and the tests can help more users when digging into their own SeatalkNG networks.

[Captain Bill]

I believe the issue is the version of the DST800 that you have requires an I70 display to calibrate it and it appears that you only have ST70s in your network. I suspect that it is likely that all you need is calibration. The common failure mode of these units is for the thermistor to fail. They tend to fail by loosing resistance. I had the analog version so I was able to read the resistance with an ohm meter when mine failed. My I70 was displaying 104 degrees F when it was about 72 degrees F. My thermistor resistance was measured at about 2K ohms when it should have been a bit over 12K. The speed sensor in these units has the same voltage supply as the speed sensor, so when the resistance of the thermistor gets too low it drops the voltage to the speed sensor and the speed side fails as well. Depth is on an semi independent circuit and is not affected by the thermistor failure. The fact that your temperature reads too low probably means the circuit to the speed/temp side only needs calibration. You can find the circuit diagrams and thermistor temp/resistance values on the Airmar web site if you dig deep enough. The st70s use the analog version of this sensor if I remember correctly so will not calibrate the digital (smart) version. The Analog versions are still available from Airmar if you don't want to buy an I70. Since the Airmar smart sensors are used by a number of companies there may be less expensive solutions to calibrating them than the Raymarine I70. I believe that some of these smart sensors are bluetooth enabled and can be calibrated by an app on a smart phone. I just checked and the app is called CAST and is available on the airmar site. Good Luck

[pjShap]

I had an Airmar GH2183 combined GPS and heading sensor. Data was available on the N2K network, but all calibration attempts failed. An excellent service technician said that while N2K data is pretty well standardized, calibration is not at all standardized. He suggested removing everything else from the network, performing the calibration (which then worked fine with the other devices off the network), and then reconnecting the rest of the network. That worked- the calibration was successful, and the calibrated data remained available with the rest of the network connected. I don't understand what goes wrong in the calibration, but if you can calibrate your sensor by removing other network items, maybe that's all you need.

[on7wp]

I have a pile of broken DST800 sensors.

It is a crappy American made product, as many others are.

They fail within 6 - 18 months. First temp, then the rest.

I have been desperately looking for other types brands, but all brands offer the very same Airmar DST-800 in whatever rebadged form. It is unreliable utterly crap and it never got upgraded in the past 25 years. They sell crap and resell it again and again and get great profit from it.

Another stupidity in this great American design is that it starts generating errors once the depth goes over 200 meters . Only thing you can do is turn it off then. How stupid the designer was not recognising the situation the sensor getting over his range loosing his echos. It would have been so easy to solve this in firmware.

I hope the designer dies really slowly in loads of pain :-)

[torrmundi]

FYI, Airmar identified a problem with voltage spike on the NMEA network damaging the transducers: https://assets-7484b3de52.cdn.insite...rt-Sensors.pdf