Bronze or Plastic DST 810

[Helmsman]

Ok. Need some advice from folks here. Would you go with a bronze or plastic DST 810? Probably staying with the 810 and have read the debates on whether speed SoG is necessary with digital solutions, and want the speed aspect of the DST 810.

What are the advantages/disadvantages to them both?

I would imagine that the bronze would need to be bonded to the rest of the underwater metal on a fiberglass boat. Is that the case for a bronze through hull?

Any help would be appreciated

 

[bowball]

Ok. Need some advice from folks here. Would you go with a bronze or plastic DST 810? Probably staying with the 810 and have read the debates on whether speed SoG is necessary with digital solutions, and want the speed aspect of the DST 810.

What are the advantages/disadvantages to them both?

I would imagine that the bronze would need to be bonded to the rest of the underwater metal on a fiberglass boat. Is that the case for a bronze through hull?

Any help would be appreciated

For my education, the speed function in the transducer measures speed through the water not Speed over ground which the gps measures. Hence you can determine effective current speed from it by the difference. (Though if the boat is not moving perfectly with or against the current the mere difference doesn’t determine actual current but effective current I assume, much like wind affects the true airspeed versus speed over ground for an airplane).

 

[twistedtree]

I have had both and the bronze ones have been bonded.

At least the bronze long tube does NOT have the builtin water flapper door thingy that blocks/slows water ingress if you need to pull the transducer for service or swap out. I’m not sure about the bronze short tube. The plastic tube has the flapper thingy.

Hopefully the 810 will be better than the 800 which was pretty much a total belly flop. The temp sensor is pretty much guaranteed to fail within a year or two, and I found the speed to be wildly off and incapable of being calibrated. If the 810 is at all like the 800, that flapper thingy will be important because you will be changing it a lot.

 

[twistedtree]

I have had both and the bronze ones have been bonded.

At least the bronze long tube does NOT have the builtin water flapper door thingy that blocks/slows water ingress if you need to pull the transducer for service or swap out. I’m not sure about the bronze short tube. The plastic tube has the flapper thingy.

Hopefully the 810 will be better than the 800 which was pretty much a total belly flop. The temp sensor is pretty much guaranteed to fail within a year or two, and I found the speed to be wildly off and incapable of being calibrated. If the 810 is at all like the 800, that flapper thingy will be important because you will be changing it a lot.

The trouble is, there really isn’t any alternative.

 

[bowball]

I have had both and the bronze ones have been bonded.

At least the bronze long tube does NOT have the builtin water flapper door thingy that blocks/slows water ingress if you need to pull the transducer for service or swap out. I’m not sure about the bronze short tube. The plastic tube has the flapper thingy.

Hopefully the 810 will be better than the 800 which was pretty much a total belly flop. The temp sensor is pretty much guaranteed to fail within a year or two, and I found the speed to be wildly off and incapable of being calibrated. If the 810 is at all like the 800, that flapper thingy will be important because you will be changing it a lot.

I read horror stories about the fail rates. My dealer said the new ones are definitely better, but I have no idea.

 

[Helmsman]

I have had both and the bronze ones have been bonded.

At least the bronze long tube does NOT have the builtin water flapper door thingy that blocks/slows water ingress if you need to pull the transducer for service or swap out. I’m not sure about the bronze short tube. The plastic tube has the flapper thingy.

Hopefully the 810 will be better than the 800 which was pretty much a total belly flop. The temp sensor is pretty much guaranteed to fail within a year or two, and I found the speed to be wildly off and incapable of being calibrated. If the 810 is at all like the 800, that flapper thingy will be important because you will be changing it a lot.

I installed a plastic DST on a previous boat and it worked just fine for four years.
I will call airmar tomorrow and ask about failure rates. Thank you.

 

[Helmsman]

Looking at the Airmar manual, it states that if you are going to leave the boat in salt water for over a week, to pull the sensor and out in the blanking plug. That tells me it is an issue in salt water, at least.

 

[Helmsman]

I have had both and the bronze ones have been bonded.

At least the bronze long tube does NOT have the builtin water flapper door thingy that blocks/slows water ingress if you need to pull the transducer for service or swap out. I’m not sure about the bronze short tube. The plastic tube has the flapper thingy.

Hopefully the 810 will be better than the 800 which was pretty much a total belly flop. The temp sensor is pretty much guaranteed to fail within a year or two, and I found the speed to be wildly off and incapable of being calibrated. If the 810 is at all like the 800, that flapper thingy will be important because you will be changing it a lot.

The bronze one comes with the valve if it is labeled as B617V.

 

[twistedtree]

The bronze one comes with the valve if it is labeled as B617V.

Thanks for decoding. Good to know.

 

[twistedtree]

I installed a plastic DST on a previous boat and it worked just fine for four years.
I will call airmar tomorrow and ask about failure rates. Thank you.

I don't know what the stats are, and doubt Airmar would ever admit anything. I asked them at METS a number of years ago and they said there was no issue that they were aware of. That's one of those answers where you are either lying, or blind to your products in the field, neither of which speaks well of the company. It's unfortunate because in all other ways I think highly of Airmar and their products.



Anyway, it's really kind of moot since there are no alternatives, so all you can do is be aware that you might need to replace it more often than you would expect. I think selecting a tube with the valve is about all you can do. I replaced my first failure during a haul out, and when the second one failed in only a few months Airmar wanted me to return it for inspection and replacement. My tube didn't have a valve and I wasn't going to shower my ER with salt water to swap in it with the boat the water, so I just had to live with it and lost the warranty coverage. So 2 out of 2 failures with no usable warranty support.


Their statement about removing it if the boat is going to be in salt water for more than two weeks tells me it's really not made for cruising boats, but more for trailered day boats.

 

[Helmsman]

I don't know what the stats are, and doubt Airmar would ever admit anything. I asked them at METS a number of years ago and they said there was no issue that they were aware of. That's one of those answers where you are either lying, or blind to your products in the field, neither of which speaks well of the company. It's unfortunate because in all other ways I think highly of Airmar and their products.



Anyway, it's really kind of moot since there are no alternatives, so all you can do is be aware that you might need to replace it more often than you would expect. I think selecting a tube with the valve is about all you can do. I replaced my first failure during a haul out, and when the second one failed in only a few months Airmar wanted me to return it for inspection and replacement. My tube didn't have a valve and I wasn't going to shower my ER with salt water to swap in it with the boat the water, so I just had to live with it and lost the warranty coverage. So 2 out of 2 failures with no usable warranty support.


Their statement about removing it if the boat is going to be in salt water for more than two weeks tells me it's really not made for cruising boats, but more for trailered day boats.

There is an alternative. It is an ultrasonic to measure speed. https://www.airmar.com/uploads/brochures/UST800-850-UDST800_SmartSensor.pdf

There are issues with this. The problems with this one are that you need a Maretron device to calibrate the speed, and the graph shows that the speed is moving up and down (not smooth) though it does match Speed over ground better. Even with the calibration, people are having a lot of problems trying to calibrate it. It is also about three times more expensive, which is ridiculous given the problems people are having calibrating it. Panbo has an article on it, and the comments section show the issues.

I may punt on having Speed through the water, and go a different direction. Perhaps just depth and temp, or maybe chirp radar with 25 degree coverage. The other option would be to get the brass DST and count on Airmar solving the UDST calibration problems, and the price becoming more realistic over time, and replace in water when the technology is is viable and the cost is reasonable.

 

[rslifkin]

As far as plastic goes, my boat has had a plastic Airmar P319 transducer for 7 or 8 years with no issues. It lived 24/7/365 in salt water for the first 4 years or so, then full time for 6 - 7 months of the year in fresh water since then.

 

[Helmsman]

As far as plastic goes, my boat has had a plastic Airmar P319 transducer for 7 or 8 years with no issues. It lived 24/7/365 in salt water for the first 4 years or so, then full time for 6 - 7 months of the year in fresh water since then.

The Airmar DST I had was plastic and worked ok for four years in fresh water. But, with the option in front of me, I will go ahead with the bronze, I think.

 

[twistedtree]

There is an alternative. It is an ultrasonic to measure speed. https://www.airmar.com/uploads/brochures/UST800-850-UDST800_SmartSensor.pdf

There are issues with this. The problems with this one are that you need a Maretron device to calibrate the speed, and the graph shows that the speed is moving up and down (not smooth) though it does match Speed over ground better. Even with the calibration, people are having a lot of problems trying to calibrate it. It is also about three times more expensive, which is ridiculous given the problems people are having calibrating it. Panbo has an article on it, and the comments section show the issues.

I may punt on having Speed through the water, and go a different direction. Perhaps just depth and temp, or maybe chirp radar with 25 degree coverage. The other option would be to get the brass DST and count on Airmar solving the UDST calibration problems, and the price becoming more realistic over time, and replace in water when the technology is is viable and the cost is reasonable.

Although it would be interesting to have, speed through water isn't really that important to me either. My first device was a DT800 (depth and temp), but when I replaced it I found that the DST (depth, speed, temp) was about the same price and more readily available, so I figured "why not".


The speed always reported about 50% faster than actual speed. A Nordhavn just doesn't move at 12 kts through the water under and circumstances. I suspect that the really large discrepancy was probably some water flow phenomenon around the hull in the proximity of the sensor. That's the only explanation I could come up with. But the real frustration was that there was no way to calibrate the speed. Airmar said to use their Weathercaster program, but it didn't support speed calibration. Only depth offset. And Maretron's calibration didn't work either, and neither company cared much about it. So I decided I didn't want STW to consume my life and abandoned it.


But shortly after, the temp failed which is what failed on the first one.


FWIW, the depth function was fine on both units, so I now look at them only as a "D" and not a "DT" or "DST", unless you get lucky for some period of time....

 

[rslifkin]

It's interesting that Airmar has so much trouble with temp sensors on the DST and DT units, as the temp sensor in my cheap transducer has worked fine from day 1. It's reasonably accurate and has been reliable.

 

[Helmsman]

I just spoke with Airmar. They are not producing the UDST right now due to a component shortage. They don’t make a Chirp transducer that will fit the 810 DST tube. .Since I don’t want to have to pull the boat to replace one, I think I will go with the DST with the hope that eventually they will solve the issues they are having with the speed portion. TT, I have read about the temp sensor failing on these things, too. Since I can replace in water with the valve, I can at least try it and have some warranty coverage for it. We will see what happens.

 

[danderer]

Although it would be interesting to have, speed through water isn't really that important to me either. My first device was a DT800 (depth and temp), but when I replaced it I found that the DST (depth, speed, temp) was about the same price and more readily available, so I figured "why not".

Same logic I followed. The speed wasn't right with the DST but I was using an open-source project to move the data to Wifi. So simple, just modify the code there to apply a speed correction to the DST data. The speed range I cared about was 0-15 knots. Except..

The DST error wasn't linear. Did some curve fitting in my correction.

More importantly the error seemed to change randomly over time. Once month fast, one slow, the next who knows? And no, there was no growth involved - the DST was clean.

Gave up on it.

 

[Helmsman]

Same logic I followed. The speed wasn't right with the DST but I was using an open-source project to move the data to Wifi. So simple, just modify the code there to apply a speed correction to the DST data. The speed range I cared about was 0-15 knots. Except..

The DST error wasn't linear. Did some curve fitting in my correction.

More importantly the error seemed to change randomly over time. Once month fast, one slow, the next who knows? And no, there was no growth involved - the DST was clean.

Gave up on it.

Would be interesting to see how they are constructed. If mine fails out of warranty, I will take it apart and try to determine how it sends its signal. The speed part of the thing is marginally important to me, due to river currents. I suspect the failure issues will be less so in freshwater. No way would I want the hassle of pulling the transducer weekly.

 

[twistedtree]

It's interesting that Airmar has so much trouble with temp sensors on the DST and DT units, as the temp sensor in my cheap transducer has worked fine from day 1. It's reasonably accurate and has been reliable.

I agree completely. I have and have had a number of transducers with temp sensors that are connected to various fish finder devices, and all have been flawless. It's just these "smart" transducers, so presumably infiltration into the embedded electronics.


One thing I have wondered but never been able to get a handle on is whether the NMEA 0183 version is any more reliable than the NMEA 2000 version.

 

[twistedtree]

I just spoke with Airmar. They are not producing the UDST right now due to a component shortage. They don’t make a Chirp transducer that will fit the 810 DST tube. .Since I don’t want to have to pull the boat to replace one, I think I will go with the DST with the hope that eventually they will solve the issues they are having with the speed portion. TT, I have read about the temp sensor failing on these things, too. Since I can replace in water with the valve, I can at least try it and have some warranty coverage for it. We will see what happens.

I think that's pretty much the only course you can take. Despite all my frustration and complaining, I installed another one in my current boat. And once again it's a long tube so in-water swap isn't practical, or at least not something I'm willing to do. I also have a separate Furuno fish finder so the DT800 is mostly a backup anyway.

 

[bowball]

I think that's pretty much the only course you can take. Despite all my frustration and complaining, I installed another one in my current boat. And once again it's a long tube so in-water swap isn't practical, or at least not something I'm willing to do. I also have a separate Furuno fish finder so the DT800 is mostly a backup anyway.

+1

 

[Helmsman]

Thanks for all the help. I ordered a bronze DST. In a few months, I will report back.