NMEA 2000/ Airmar DST 810 help

[patja]

I currently have three DST-810 transducers in my possession, including a rev 2 and a rev 3 model that are under one month old. None of them work as expected. I am actively pursuing solutions with the support of my dealer, Fisheries Supply, and Garmin.

Fisheries has been excellent with their support, as usual. Garmin has been good-ish once I get the callback after waiting one to two hours.

Symptoms are that some of the time it powers up and gives accurate depth. More often it reads some minimum value like 2.2 or 3.3 feet, or just ---. Even when it starts accurate, it usually reverts to the failure mode after some time. This is all with testing mostly sitting at the dock, but I was out for a weekend trip last weekend and it didn't work well at all then.

Garmin says that if it works some of the time, the product is good and I should be able to work through and eliminate whatever else in my environment is causing the problem. They said build an all new N2K backbone with new tees (just singles, no double/quad tees, to make it easier to isolate problems) and a new power cord. They recommend running the power all the way back to the battery like a bilge pump, in an "always on" circuit. Build the simplest N2K network ever with just power, chartplotter, and DST-810 and the terminators, again with all new tees and power cable. He said if it works some of the time, it must be either a power problem or a data connection breakdown somewhere (old bad tees). Seems like a reasonable troubleshooting approach.

So I bought all new tees, new terminators, and a new Garmin power cable.

I tested the power two ways. I pulled my existing N2K power cable off of my "electronics" breaker and terminal strip that feeds all instruments and put it on a separate breaker. I also brought a separate and isolated small Dakota LFP battery to power my test N2K backbone completely independent from the boat's DC system. I was wondering if something like the fridge compressor might be causing problematic noise on the power circuit.

For my "simplest N2K network ever" I didn't do exactly what the Garmin rep suggested. My chartplotter is mounted above my companionway in a space that is quite a project to get behind and do things like unplug the other displays and AP control head that are there from the network. Instead my simple network consists of an Actisense NGT-1 USB device where I can view all the N2K activity on my laptop, a tee for power, and the DST-810. No connection to any other devices or boat power. This does seem the most reliable scenario, but it is not flawless. It yields about a 75% success rate. And that goes down the more devices I add to the backbone.

I question the Garmin support a bit. The rep demonstrated a glaring lack of knowledge about two aspects of the Garmin product line. I suggested that the simplest N2K backbone for testing could be even smaller than three tees: it should be possible to set it up with just the power and the DST-810, because I can see if it is reading depth using the Airmar Cast app that connects to the DST-810 over Bluetooth. The rep was adamant in his conviction that I was wrong about that because he does not believe the DST-810 has any wireless capability on its own. He said if I was getting data on my phone from it, that had to be relayed from "some other device" on my boat. I prodded him on this as I was equally certain that it does support Bluetooth connectivity on its own, which is the truth and is clearly touted as a feature in the product specifications. But he doubled down on his statements that this is incorrect. And when I said that to run the power cable all the way back to my main battery "always on" circuits I would need to wire up an extension to it with some butt connectors, he said my dealer would have a longer version. I can find no evidence that Garmin makes a longer N2K power cable. I was wondering about extending the "shield" wire. So that's a concern, especially as it bears on his certainty about the product behavior and expectation that if it works some of the time, it should be possible to get it working all of the time.

I have a Fluke 117 DMM which beeps and shows deviations in the Max and Min voltage. It hasn't revealed any power spikes to explain any failures, but I haven't put it on a bare lead from the N2K network so maybe I am not measuring this well enough by looking just at the power voltage at the source.

It is all very frustrating and has required many hours of troubleshooting over the past two weeks. As well as half a dozen removal and insertions of the transducers, which brings in about 5 gallons of seawater each time. Good for bilge pump testing I guess. Each time it is a three-towel job to clean up what doesn't end in the bilge from the gusher.

I also have a P79 transducer on a Garmin GSD-22 that had gone out on me a year or so ago. I replaced it and it works flawlessly. I am thinking the long term solution might be to abandon the DST-810 and go with a dedicated speed sensor like the GST-43 and just use the P79 for depth. But that will require a new through hull.

The journey continues. My daughters are signed up to help me take it out and put it through its paces away from the dock for Father's Day tomorrow. We'll see how that goes, and what my next call with Garmin yields.

Just for completeness and in case this jogs anyone's memory of known issues with other devices of which I am unaware, my N2K network when fully built out includes the following: 7607xsv chartplotter, Garmin 9 axis heading sensor, Vesper XB8000H AIS transceiver, DST-810 triducer, Raymarine P70s autopilot control head, Garmin GNX20 display, Garmin GNX Wind display, Garmin GND10 wind sensor and black box, and for some reason the Raymarine SPX30 autopilot also shows up as a listed device, I guess because the P70s exposes it or translates from the Seatalk connection they share (it has no direct connection to the N2K backbone). I also have a Victron Cerbo and a bunch of Victron devices it exposes when connected, and the Actisense NGT-1 which I am keeping disconnected from any final backbone configuration for simplicity as I don't see them as providing essential information.

[crosswire]

Earlier, I reported losing temp, then speed, and finally depth from a DST 810. The 810 turned out to be a 2017 model, so I bought a new one dated March, 2024. The new unit now has an erratic depth display after one month. The readings are from normal expected depths of 8 to 9 feet up to 50 or more.

The instrument system contains both standard NMEA2000 and SeaTalk ng, with a SPX30 and a p70r for the autopilot. I still get low voltage warnings from the p70r, even though the unit voltage displayed on the chart plotter is 11.8 or better. The p70r and the plotter are the same cable distance from the NEMA 2000 power supply. Note - I had thought the old 810 may have been dragging down the network voltage, but that does not seem to be the case.

From what I have read on this thread, there does seem to be something dodgy with the 810s. However, I do like the attitude data the new 810 provides; very helpful when loading the boat.

[patja]

After another four hours of testing, I've come to some conclusions and am ready to close the book on this chapter. tl/dr: I think it is all down to my thru hull. A little embarrassing and counter-intuitive, but here are the details of this hard-earned knowledge which I hope can help others facing challenges with this product.



My boat is almost 40 years old. I'm not sure if the transducer thru hull is original, but it is certainly older than almost all of my other thru hulls, almost all of which were replaced by a previous owner circa 2000.



In addition to the flaky depth readings, I observed that the new Rev 2 and Rev 3 DST-810s I tested were not reading boat speed when mounted in the thru hull. This was puzzling as they read speed just fine when I spin the paddlewheel out of the water, and when I strap it to a boat hook and wave it back and forth in the water.


I thought maybe there is a foreign object or marine growth to blame. So I put on my wetsuit and snorkel gear for an inspection and found that the paddlewheel was not spinning freely. I pulled it and gave it a very slight squeeze at the thin outer piece of the housing adjacent to the paddlewheel. This piece flexes slightly, enough to bind the wider paddlewheel in the Rev 2 and Rev 3 DST-810s. I surmise that my thru hull must need a good reaming/sanding to correct this, something difficult to do in the water. Or replacement...it would be nice to have a thru hull with the flap. A task for the next haulout.


Then I got to thinking, if the thru hull was interfering with the paddlewheel, might it also be contributing to the flaky depth reading? Feels unlikely, but this was the one element of my test that was still tied to my boat. Just today I had tested the Rev 2 model I have in the thru hull, and only 2 out of 10 controlled tests yielded a depth reading. So I strapped it to my boat hook, put it in the water, and tested it. I could not get the thing to fail. I don't understand this, but can't deny the result. Maybe it is getting squeezed in my thru hull in a way that compromises the sonar or the electronics inside somehow?


Moral of the story is never discount the influence of your boat and its unique environment on an unexpected outcome.


I cleaned up my old Rev 1 DST-810 with the narrower paddlewheel and reinstalled it. It reads speed just fine. It has much more room to either side of the paddlewheel and doesn't bind in my thru hull. I never had problems with it for boat speed measurement, just depth (which is still flaky). Given I have the P79 working reliably for depth, I can live without depth on the DST-810 until I replace that thru hull.

[Dockhead]

Originally Posted by patja

After another four hours of testing, I've come to some conclusions and am ready to close the book on this chapter. tl/dr: I think it is all down to my thru hull. A little embarrassing and counter-intuitive, but here are the details of this hard-earned knowledge which I hope can help others facing challenges with this product.

My boat is almost 40 years old. I'm not sure if the transducer thru hull is original, but it is certainly older than almost all of my other thru hulls, almost all of which were replaced by a previous owner circa 2000.

In addition to the flaky depth readings, I observed that the new Rev 2 and Rev 3 DST-810s I tested were not reading boat speed when mounted in the thru hull. This was puzzling as they read speed just fine when I spin the paddlewheel out of the water, and when I strap it to a boat hook and wave it back and forth in the water.


I thought maybe there is a foreign object or marine growth to blame. So I put on my wetsuit and snorkel gear for an inspection and found that the paddlewheel was not spinning freely. I pulled it and gave it a very slight squeeze at the thin outer piece of the housing adjacent to the paddlewheel. This piece flexes slightly, enough to bind the wider paddlewheel in the Rev 2 and Rev 3 DST-810s. I surmise that my thru hull must need a good reaming/sanding to correct this, something difficult to do in the water. Or replacement...it would be nice to have a thru hull with the flap. A task for the next haulout.

Then I got to thinking, if the thru hull was interfering with the paddlewheel, might it also be contributing to the flaky depth reading? Feels unlikely, but this was the one element of my test that was still tied to my boat. Just today I had tested the Rev 2 model I have in the thru hull, and only 2 out of 10 controlled tests yielded a depth reading. So I strapped it to my boat hook, put it in the water, and tested it. I could not get the thing to fail. I don't understand this, but can't deny the result. Maybe it is getting squeezed in my thru hull in a way that compromises the sonar or the electronics inside somehow?

Moral of the story is never discount the influence of your boat and its unique environment on an unexpected outcome.

I cleaned up my old Rev 1 DST-810 with the narrower paddlewheel and reinstalled it. It reads speed just fine. It has much more room to either side of the paddlewheel and doesn't bind in my thru hull. I never had problems with it for boat speed measurement, just depth (which is still flaky). Given I have the P79 working reliably for depth, I can live without depth on the DST-810 until I replace that thru hull.

Congratulations on the successful diagnosis and resolution of the issue!

[flee27]

Thanks patja for the details. I have been holding off on adding speed to my boat because of all of the issues with the DST810. Hopefully they have actually resolved the issues with this unit.

I also have a P79 depth sensor. I will definitely be leaving it installed as a back up.

Best
Foster

[Dockhead]

Originally Posted by flee27

Thanks patja for the details. I have been holding off on adding speed to my boat because of all of the issues with the DST810. Hopefully they have actually resolved the issues with this unit.

I also have a P79 depth sensor. I will definitely be leaving it installed as a back up.

Best
Foster

If you have two through hulls for depth and speed, why would you consider a triducer? Squeezing all that in one transducer requires the whole paddlewheel system to be made smaller, which is not good geometrically for a paddlewheel sensor.


My all means, go separate speed and depth, if you have the throughhulls for it, would be my advice.

[BluewaterKarma]

We are in the Sea of Cortez and we have two apparent problems with the B&G DST 810. First we noticed over the last few days is that the sea temp is reading really high. It was in the 90s which could be, but today we saw 110 degrees. Ridiculous!

Second, I hate how the depth flips over when it hits really deep water. I come up from below to see to my surprise 6 feet of water .. that races your heart pretty fast. For peets sake, once it goes to dashes, dont flip over, just stay dashes until it goes below that threshold again.

[Fuss]

Originally Posted by Dockhead

If you have two through hulls for depth and speed, why would you consider a triducer? Squeezing all that in one transducer requires the whole paddlewheel system to be made smaller, which is not good geometrically for a paddlewheel sensor.


My all means, go separate speed and depth, if you have the throughhulls for it, would be my advice.

Good points but you have no redundancy.
I spent 6 months once with no depth, I was in this time up a river for a few days which made this even worse. Sometimes I was even using a lead line.


I would put a dst810 in the speed hole (you can alter the angle with the software) and a dst800 in the depth hole. This way you have some redundancy ... ok ok, I know the dst810 seems to be not the most reliable ...and they really need to fix this.


Sailing around with no depth is not good and can take months if you have no spares on board.

[kaz911]

Quick question to everybody with DST810 issues.

How many of you have put normal anti-fouling paint on the plastic of the transducer?

I have been checking where our boat is hauled out - and I would say it is about 2/3rds of boats paint plastic through hulls with normal anti-fouling paint.

Most plastics can become damaged from the paints causing splits or swelling. I did see a couple where the "wheel holders" on the DST8xx's was under pressure due to a lot of bottom paint and/or swelling - so hole was too tight - and DST jammed in. Result - dead DST.

[Dockhead]

Originally Posted by Fuss

Good points but you have no redundancy.
I spent 6 months once with no depth, I was in this time up a river for a few days which made this even worse. Sometimes I was even using a lead line.

I would put a dst810 in the speed hole (you can alter the angle with the software) and a dst800 in the depth hole. This way you have some redundancy ... ok ok, I know the dst810 seems to be not the most reliable ...and they really need to fix this.

Sailing around with no depth is not good and can take months if you have no spares on board.

I personally have redundant depth because I have forward looking sonar, which also does depth, in a third through-hull.


But in any case I have spare transducers, and it's simple enough (if sphincter-tightening) to swap them out with the boat in the water.


So if you've got two holes, why not a good depth transducer in one, and a good speed transducer in the other? And a spare depth transducer on board? I don't see the benefit of a crappy tri-ducer in both holes.

[BluewaterKarma]

I do see that Airmar has released a new DST850 that has no moving parts. Perhaps a great improvement. But, probably the biggest problem with Airmar is they have no competition.

[Fuss]

Originally Posted by BluewaterKarma

I do see that Airmar has released a new DST850 that has no moving parts. Perhaps a great improvement. But, probably the biggest problem with Airmar is they have no competition.

i better sort this out, i have a spare dst800 that’s analog so that’s redundant..… do you have a link as no moving parts would be good… you never know, it might even be as reliable as the dst810!!!

ok… i’ll say it again…. nmea2000 must be behind a dc dc converter running at 12.5v and ideally have its own mini battery after this to further protect.

[kaz911]

Originally Posted by BluewaterKarma

I do see that Airmar has released a new DST850 that has no moving parts. Perhaps a great improvement. But, probably the biggest problem with Airmar is they have no competition.

Don't you mean the UST850? Ultrasonic Speed and Temperature? (So no depth)

The Ultrasonic's have their own issues..

/k