Airmar DST800 problems - again

I've read a lot about people having failures with Airmar DST800 depth/temp/speed sounders. Me included. I'm on my second - and last - failure now. Just go read TheHullTruth or CruisersForum and you will see that a lot of people have experience failures on these devices.

These are thruhull transducers that connect directly to NMEA 2000 and, depending on the model transducer, provide depth, temp and speed thru water.

My first - a depth + temp model - started reading crazy water temps after maybe 2 years, and just out of warranty. When I hauled out last December (about a year ago), I replaced it to the tune of about $500.

The replacement included speed in addition to depth and temp. It only cost a little bit more, so I figured what the heck. The speed has never worked properly. It ready about 50% faster than I am actually moving. One might think it's simple calibration process to fix that, but not so. Maretron has a calibration capability, but it didn't work. I then noticed that it disappeared in their next software release. Airmar has a tool, but it doesn't let you adjust speed. I am told that other vendor's displays have an adjustment feature, but I don't want to buy a several hundred dollar display just to calibrate (hopefully) a transducer that is supposed to operate as a stand alone device. So for the past year I have just ignored the speed reading that I paid extra for.

A week ago I got back on the boat, and noticed that there was no temp reading. Some investigation showed the DST800 reporting blank data in the N2K messages that it sends, so clearly a faulty transducer.

I talked to Airmar - actually Gemeco who provide all their support - and they will consider replacing it under warranty, but need me to return it so they can test it first. To return it, I need to pull it out of the thruhull flange, spraying salt water all over my engine room, and install a plug. Then, once they have agreed that it's failed, ship me a new one in Mexico (good luck with that), where I can once again flood my engine room with salt water. And I get to do that to replace a device that by all experience will just fail again.

To limit the salt water shower to one rather than two, I purchased a new DST800 on agreement that I would be credited full price if the warranty return was approved, so I did that, including overnight shipping because I'm about to leave.

It arrived this morning, but the more I thought about salt water spraying all over my engine room and dousing all sorts of stuff, I said No. This just isn't worth it. I'll eat the cost of the device since I will lose my warranty claim, and deal with it at the next haul out. And at that time I'll replace it with something else that is more reliable. The replacement that I bought in advance is getting returned today. Fool me once, shame on you. Fool me twice, shame on me. The DST800 now goes on the wall of shame.

My experience with Airmar transducers has been quite good, except for this one. I suppose that's a good thing since they are the only game in town and make the transducers for everyone. I don't know of any other vendor. But the DST800 is a POS.

twistedtree said:

The replacement included speed in addition to depth and temp. It only cost a little bit more, so I figured what the heck.

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My 8-year-old DT failed and I got a DST using the same logic. Mine has never read speed correctly. I can compensate for that. But it also has never read consistently. Hard to apply a correction in that case. I wound up just blocking the STW data from the network.

If you find a better solution I'd love to hear about it.

My DT800 is also producing còrazy and unstable temps and more recently depth has been whacky too. Is anyone aware of an alternative N2K sensor? Airmar has apparently released an "u ltrasonic" model recently....but Panbo.com has some negatives about that too.

Aquabelle said:

My DT800 is also producing còrazy and unstable temps and more recently depth has been whacky too. Is anyone aware of an alternative N2K sensor? Airmar has apparently released an "u ltrasonic" model recently....but Panbo.com has some negatives about that too.

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I've been looking too, but no joy. I wonder if the 0183 version is any more reliable? Right now, I'm leaning towards multiple Furuno FCV628s with conventional transudcer. Mine has been flawless for 4 years, and outlived two of the N2K POS devices.

twistedtree said:

I've been looking too, but no joy. I wonder if the 0183 version is any more reliable? Right now, I'm leaning towards multiple Furuno FCV628s with conventional transudcer. Mine has been flawless for 4 years, and outlived two of the N2K POS devices.

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Agreed. My 10+ year old 0183 depth 'ducer has never missed a beat. I got the DT800 thinking it would be my main depth instrument, then re-ordered it as the backup and now, it isn't even that. Temp was just 'interesting' and of no practical use given I don't fish seriously. Panbo has a recent write-up of an 'ultrasonic' version of the D(S)T800....with quite a lot of scepticism about Airmar's history/capacity to deliver:

https://www.panbo.com/airmar-2018-p...-speedo-mysteries-unraveled-plus-new-udst800/

If I could revive an old thread: I too have an Airmar DST800 triducer (NMEA 2000). Depth and temp seem fine but I have to say waterspeed stopped working maybe a few weeks after installation. I've checked the paddle wheel and it spins freely...
Did anyone find more reliable alternatives to this product? I guess I could live without water speed but it would be very handy in many cases for predicting arrival somewhere as well as just improved situational awareness.

As far as I know, Airmar is the only game in town.


But if calculated arrival time is what you want, you GPS speed-over-ground will be more accurate, and a better predictor of your arrival time since it's speed over ground rather than speed thru water.

I also have a DST800 and it's been reliable for the most part. I have had one or two occasions where the STW paddle wasn't reporting, but I chalked that up to disuse and potential growth on the assembly. A few minutes on plane and it was back in action.

Here is what I wonder about a question you pose and a POS assertion. Help me to understand. Whether it is NMEA 2000 or NMEA 0183, both are just wires that transmit data. Why would one be any more reliable than the other? On board I have a Simrad forward-looking transducer (yes, Twistedtree, I know you hate Simrad products) that has worked just fine since I installed the system four years ago. It is all NMEA 2000. Perhaps the transducer will crap out tomorrow. Who knows. By the way, I would not purchase anyone's forward-looking sonar again. In four years of 7,000 miles of cruising much of which in shallow water, I have found it to be of no use. The depth-finding however works just fine as does the temperature function. I also have an old Standard Horizon DT35 dedicated display sonar. It reports the same depth, pretty much, as the Simrad ducer.

twistedtree said:

I've been looking too, but no joy. I wonder if the 0183 version is any more reliable? Right now, I'm leaning towards multiple Furuno FCV628s with conventional transudcer. Mine has been flawless for 4 years, and outlived two of the N2K POS devices.

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twistedtree said:

As far as I know, Airmar is the only game in town.


But if calculated arrival time is what you want, you GPS speed-over-ground will be more accurate, and a better predictor of your arrival time since it's speed over ground rather than speed thru water.

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When I had a paddlewheel for speed through the water, my primary use of it was getting the difference in STW and SOG to figure river currents.

catalinajack said:

Here is what I wonder about a question you pose and a POS assertion. Help me to understand. Whether it is NMEA 2000 or NMEA 0183, both are just wires that transmit data. Why would one be any more reliable than the other?

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0183 is a relatively 'simple' serial protocol link. Two wires, xmit and recv between two devices, that's it. Works great if you're connecting into a central device like a chartplotter. Not so much if you have more than one plotter, or other display device.

NMEA2K is a network protocol supporting hundreds of devices all communicating on the same segment of wires, quite a lot more complicated. A great many issues emerge when N2K networking gets complicated.

It's not quite the simple 'plug-and-play' some folks think it is. Mostly, folks skimp on the type of wire between devices and lengths, mixing and matching brands, and not paying close attention to the network requirements. This leads to a network that "sort of works" but then it doesn't.

Though I would not attribute N2K (mis)configuring to the criticisms of the DST800, as that seems to have trouble regardless of how it's connected.

Interesting to note the real-world experience on the forward-looking sonar. I'm sure it's useful for someone, but I could never envision it being much use for our boating needs either. I've long wanted side-scan, if just for the fun of it, but it's never risen far enough up the list of "what she'll let me get away with buying".

Thanks for the explanation. I guess I was dumb lucky. I have an MFD, VHF radio, a auto pilot computer, an autopilot control head, an AIS, and a radar all on a NMEA network. It was instant plug and play for me. The AIS and VHF radio are of different manufacture than the rest of the components. I guess when it works, it works but, when it doesn't it must drive folks crazy. Cables and connectors are all high quality.

wkearney99 said:

0183 is a relatively 'simple' serial protocol link. Two wires, xmit and recv between two devices, that's it. Works great if you're connecting into a central device like a chartplotter. Not so much if you have more than one plotter, or other display device.

NMEA2K is a network protocol supporting hundreds of devices all communicating on the same segment of wires, quite a lot more complicated. A great many issues emerge when N2K networking gets complicated.

It's not quite the simple 'plug-and-play' some folks think it is. Mostly, folks skimp on the type of wire between devices and lengths, mixing and matching brands, and not paying close attention to the network requirements. This leads to a network that "sort of works" but then it doesn't.

Though I would not attribute N2K (mis)configuring to the criticisms of the DST800, as that seems to have trouble regardless of how it's connected.

Interesting to note the real-world experience on the forward-looking sonar. I'm sure it's useful for someone, but I could never envision it being much use for our boating needs either. I've long wanted side-scan, if just for the fun of it, but it's never risen far enough up the list of "what she'll let me get away with buying".

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rgano said:

When I had a paddlewheel for speed through the water, my primary use of it was getting the difference in STW and SOG to figure river currents.

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Agreed; rivers or current through channels.....

catalinajack said:

Here is what I wonder about a question you pose and a POS assertion. Help me to understand. Whether it is NMEA 2000 or NMEA 0183, both are just wires that transmit data. Why would one be any more reliable than the other? On board I have a Simrad forward-looking transducer (yes, Twistedtree, I know you hate Simrad products) that has worked just fine since I installed the system four years ago. It is all NMEA 2000. Perhaps the transducer will crap out tomorrow. Who knows. By the way, I would not purchase anyone's forward-looking sonar again. In four years of 7,000 miles of cruising much of which in shallow water, I have found it to be of no use. The depth-finding however works just fine as does the temperature function. I also have an old Standard Horizon DT35 dedicated display sonar. It reports the same depth, pretty much, as the Simrad ducer.

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I don't now why one would be more reliable than the other. That's why I said "I wonder". It's based on an observation that I hear about failures of the N2K version, and not the 0183 version. I don't know if it's significant.

BTW I don't think there is any N2K issue with the DST800. It's just a seemingly high failure rate device than happens to be N2K. So although I'm often quick to take a swing at N2K, there is no cause to do so in this instance. I was really wondering if maybe there were construction differences between the N2K and 0183 versions, internal electronics reliability differences, etc.

With a background in developing embedded electronics such as you'd find in these types of devices, the level of complexity to build a 0183 device vs. an N2K device is pretty significant.

There are literally thousands of mini cpus that can do standard serial (0183), and a much, much smaller subset that are able to do CANBUS (N2K) and also have the capacity to run enough software to comply with the mystical, secret N2K protocol on top of that hardware. Perhaps complexity is the wrong word, but component choice. The software is also going to be much more complicated and require more skill to implement correctly.

While in theory it should be 'just wires that transmit data', it's a whole different ballgame to comply with N2K vs. 0183, especially from a software implementation perspective. The secret protocol makes things even harder as there can be no sharing of knowledge or advance of the state of the software as a community. Each developer/company has to work within the confines of the secret club as defined by the standards body, this severely handicaps developers, I speak from experience.

I've had to decode and implement 'secret' wire level protocols before and it is not easy. There is no way to know if what you create is reliable in the variety of different environments where your device might be placed and no pool of community to share strategies with.

A DST810 with Bluetooth is on the schedule for my boat and it has even more electronic and software complexity than the 800, hopefully it will be reliable enough. Whether the DST800 failures are hardware or software I don't know.

If someone has one that has failed, it would be interesting to open it up and see what's inside. If someone wants to send me a broken one that is of no usable value, I'd be happy to do that and post up the results.

I have two DST800s aboard, and both have been failing in random ways in the last 2 months. One reads depths completely wrong for hours at a time, and then starts working again. I've cleaned it in the water and out to no avail. The other has issues with the speed wheel, yet it is clean (I've pulled it once a week). I spent an hour today just looking for alternatives, but found none that will fit in the same hole that aren't from Airmar. The ultrasonic ones, which I have had, are no better. In fact, they have a whole new set of problems.

STW is important for my autopilot to function correctly. Otherwise, if it wasn't, I'd just have depth/temp and get rid of spinny things that get clogged with crap. You can set most autopilots to use SOG instead of STW but weird things happen in my experience.

stevemitchell said:

STW is important for my autopilot to function correctly. Otherwise, if it wasn't, I'd just have depth/temp and get rid of spinny things that get clogged with crap. You can set most autopilots to use SOG instead of STW but weird things happen in my experience.

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Interesting comment. I've never had STW available to my pilots. Only SOG (and others). What sort of weirdness have you seen?

twistedtree said:

Interesting comment. I've never had STW available to my pilots. Only SOG (and others). What sort of weirdness have you seen?

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Furuno allows you to pick SOG, STW or manual (on some of the older ones for the last value) and used to recommend STW since SOG can vary quite a bit with the older GPS, or even a high up mounted one, like the Airmar WX series I had for a long while.

However, you bring up a good point - since I installed the SCX-20 and even wrote up an article on it, I should have thought to change it to SOG since that is rock solid now.

With STW if it is mis-calibrated or wrong, the autopilot would vary left to right slowly over time, with XTE increasing, and then decreasing as it corrected it. I've seen up to 30 yards of XTE as a result, when I normally see 1-3 yards when things are happy. I spoke with Furuno about it a year or two ago, and it was definitely tied to funky STW. Switching it to SOG at the time made it somewhat better, and also worse at times.

I'll have to change it to SOG now with the satellite compass and see how it does.

stevemitchell said:

Furuno allows you to pick SOG, STW or manual (on some of the older ones for the last value) and used to recommend STW since SOG can vary quite a bit with the older GPS, or even a high up mounted one, like the Airmar WX series I had for a long while.



However, you bring up a good point - since I installed the SCX-20 and even wrote up an article on it, I should have thought to change it to SOG since that is rock solid now.



With STW if it is mis-calibrated or wrong, the autopilot would vary left to right slowly over time, with XTE increasing, and then decreasing as it corrected it. I've seen up to 30 yards of XTE as a result, when I normally see 1-3 yards when things are happy. I spoke with Furuno about it a year or two ago, and it was definitely tied to funky STW. Switching it to SOG at the time made it somewhat better, and also worse at times.



I'll have to change it to SOG now with the satellite compass and see how it does.

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Very interesting. I’ve just played with different quality heading sources, and that seem to make a big difference too. Not just heading, but ROT too.

It's interesting... My DST800 actually shows up as a DST200 on my NMEA 2000 network from all devices. It's definitely a DST800 that I bought less than a year ago.

Contemplating going to a DT800 and ditching the speed wheel to see if that product is any better. Anyone tried that model?

stevemitchell said:

It's interesting... My DST800 actually shows up as a DST200 on my NMEA 2000 network from all devices. It's definitely a DST800 that I bought less than a year ago.

Contemplating going to a DT800 and ditching the speed wheel to see if that product is any better. Anyone tried that model?

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Mine always showed up as a DT200 as well. Hey, why have one name for a product when you can have two? I'd say someone flunked Branding 101.


My first foray with these devices was a DT800, exactly as you are contemplating. The depth part worked fine, but the temp failed somewhere between year 1 and year 2. When I replaced it, I used a DST800 because it was just about the same price, and I figured it would be fun to have STW. STW never worked, always reporting about 50% higher than actual speed. And the temp failed within months.

twistedtree said:

Mine always showed up as a DT200 as well. Hey, why have one name for a product when you can have two? I'd say someone flunked Branding 101.


My first foray with these devices was a DT800, exactly as you are contemplating. The depth part worked fine, but the temp failed somewhere between year 1 and year 2. When I replaced it, I used a DST800 because it was just about the same price, and I figured it would be fun to have STW. STW never worked, always reporting about 50% higher than actual speed. And the temp failed within months.

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Yeah I am not sure why they can't change the model number. The code someone wrote years ago for NMEA 2000 just never got updated....

I care mostly about depth, then speed through water, and then temp, so the DT800 looks like one of the best choices. I would be fine just having depth, and nothing else. Speed through water is useful if you are in a current, but the little wheel is such a pain to maintain.

I don't want to haul the boat, and I have two of the 617V style through hulls already in place, so ideally I'd love two sensors for redundancy, or even one for speed and one for depth. That's what the boat had when I bought it, older Furuno branded models that were NMEA 0183, and should have just left them alone

I really wish there were more choices!

I posted about this on Panbo this morning and Steve mentioned this thread.
We just recently returned from getting hauled out. I installed one of the new DST810s. Having issues with it already. Depth appears to randomly display ~15ft for sometimes seconds or hours and then will return to the true depth. Airmar app is kinda cool but no real help for diagnosing the problem. I've confirmed the values are the same throughout my network and depth is the only PGN that randomly acts up. Going to try and engage Airmar/Gemeco for replacement or troubleshooting.

Here's what my Grafana is showing overnight.

Update: our DST 800 is now working again; partly due to operator error. We had moved to a very southern climate we were not familiar with where there is faster marine growth. Some of you probably already know this but if you read the instruction manual on the DST series, it will recommend applying anti-fouling paint on the sensor. Not surprising I guess but have to admit i was surprised it even says to apply it on the paddle wheel.
Anyway we had a diver clean the bottom one time and i asked him if the paddle wheel was running freely. he said yes.... but when I went to pull it out to check it, sure enough there was enough gunk that it would spin, but not "freely".
We thoroughly cleaned it this time and I had found this handy 2-oz. bottle of anti-foul specifically made for transducers. it has a built-in applicator brush about the size you'd find for auto touch-up. Let it dry, re-connected and found the water speed works again. Once installed we also have accurate depth and temp. Fingers crossed it keeps working but at least I'll know what to look for if it stops.

If your transducer and/or paddle wheel cannot be withdrawn into the hull while afloat, you can get some lanoline on a rag and smear it on underwater for a surprisingly lasting temporary fix until next haulout. Been there and dunnit.

Thanks Rgano, I don't know how many transducers have this, but our DST800 thru-hull comes equipped with a flap-valve for easier removal. It has a spring-loaded closure when you pull the DST out. It is by no means water tight; you still get a small burst of sea water but it is small and very manageable, I'd say we get about 12 ounces of liquid in the whole process.

Any update on the reliability of the DSt800? I’m scheduled to have one installed this winter.

I have two DT800 transducers from 2015. The depth readings on both are perfect, always have been. Temperature function died on both within a couple of months of recommisioning the boat.

I have a third Airmar depth transducer that's connected to a Garmin GSD 22 video depth sounder black box. That black box uses a data cable (not NEMA 2000) to tie it to the MFDs. That transducer was also replaced in 2015 when it was moved to a different location. Both depth and temperature have been perfect.

Ted

On our DST 800, for the most part the depth and temp continue to work. Water speed remains inconsistent but we can get it to work if we're diligent in keeping the sensor clean. The transducer paint helps and if all three values (DST) are your objective, you might have to pull it and manually clean it roughly once or twice per season.
I've considered the new UDST800 but I don't think we want to spend a boat buck on it, not knowing if it will perform a lot better.