Replacing the broken DST800

[tradrockrat]

Hi all - so now that it's official, and I own the TY37, it's time to get to work (you know - "work" as in research, spend money, make lots of mistakes, spend more money, and do it all from lockdown at home...)

The boat needs some TLC, but I've got to put together my electronics package as a scaleable thing, a few pieces at a time. We'll be making blue water passages and need to plan with that in mind

This post is a question about the broken DST800 currently installed on the starboard side of the hull. For obvious reasons, I'm just going to replace it using the same hole. Seems silly to look for alternatives to the DST when there's a damn hole there that needs filling.

HOWEVER... It seems the more I research, the less I know. I really just NEED depth. Speed and water temp are nice, but not necessary.

1. Why are there three sensors smashed together into a package that - according to the internet at least - only lasts a few years before breaking? I see two sensor sets as well, and if one is depth, I'm happy with that if they are more reliable. Are they?

2. And as the hole in the hull is already cut, how do I figure out if I need a 0, 10, 20 degree "offset"? Is that even a thing for sailboat installations?

3. Which brands are plug and play nmea2000 with no proprietary calibration needed? I want to run mine straight to a tablet running iNavx/Navionincs/OpenCP (not sure exactly where I'm going yet as the ultimate goal is offshore cruising and that will drive decision). Eventually I'll get a dedicated MFD for the cockpit, but that will be right before jumping off to the Caribbean as our first stop in a circumnavigation starting in late 2021 (again, assuming COVID allows international travel ).

4. Some brands can be removed for cleaning??? Does that mean I might be able to just yank the bad one and drop in a good one? Anyone who knows me at all knows there's NO WAY it could be that easy for me to fix - my karma doesn't work that way - but I should definitely look first. What am I looking for?

Thanks in advance!

[smac999]

If the current one is a dst800. It just unscrews and gets replaced. Takes 30 secs. (Well plus runing re cable). They are designed to be pulled out and swapped while in water. Yes You will get a little wet. Every paddle wheel does this.

I don’t think the 800 comes with hull offsets. It’s only 0.

So if the hull is angled. It may point sideways and the reading will be off.

[tradrockrat]

Originally Posted by smac999

If the current one is a dst800. It just unscrews and gets replaced. Takes 30 secs. (Well plus runing re cable). They are designed to be pulled out and swapped while in water. Yes You will get a little wet. Every paddle wheel does this.

I don’t think the 800 comes with hull offsets. It’s only 0.

So if the hull is angled. It may point sideways and the reading will be off.

Thanks for the info. Are DST's like some other things as far as makers - Pretty much all made in the same shop somewhere and then labeled for different marine electronics companies?

Because I've read that some need calibration through a proprietary MFD / display and some do not. I'm wondering what to look for as far as that goes.

[GordMay]

According to Airmar:
Transducers that become physically damaged may need to be replaced, but beyond that they normally offer many years of great service.
What most do not know is that ceramics themselves age in decades (multiples of 10). Over time, they can drift in frequency. Transducers that are between 10 and 20 years old should still work well enough, but will probably produce less energy than when they were new.
Beyond 20 years is pushing the limits and one should seriously consider changing the transducer.

[tradrockrat]

Originally Posted by GordMay

According to Airmar:
Transducers that become physically damaged may need to be replaced, but beyond that they normally offer many years of great service.
What most do not know is that ceramics themselves age in decades (multiples of 10). Over time, they can drift in frequency. Transducers that are between 10 and 20 years old should still work well enough, but will probably produce less energy than when they were new.
Beyond 20 years is pushing the limits and one should seriously consider changing the transducer.

I can't get to my boat right now to check exactly what is in there, but during the haul out for the survey, the paddle wheel was noted to be broken. So I know this one needs repair/replacement. And not knowing how old it is, I want to replace it.

[Redline452]

The transducer is retractable, basically removeable and can be replaced by a blanking plug (make sure you have one). So unless the mounting flange is damaged, you can just pull it from the inside, whether afloat or not. The paddlewheel alone is replaceable if that's all that is broken.



Normally depthsounders have a fairly wide beam; the DST800 is spec'd at 44 degrees, and rated for up to 22 degree deadrise, so unless your installation is truly angled, I'd not worry and just replace it with the same. Even if the hull was angled more, the speed and temp should work regardless; only depth readings will begin to depend on the angle of heel.


In my experience the biggest nuisance with depth transducers is that (for good reasons) the cable is captive to the transducer so replacing it usually means re-running the whole thing from the transducer back to the instrument. On the other hand, this almost never happens. An N2K transducer would only need to be cabled back to the nearest hub, so maybe simpler.

[sainted]

Originally Posted by tradrockrat

Thanks for the info. Are DST's like some other things as far as makers - Pretty much all made in the same shop somewhere and then labeled for different marine electronics companies?

Because I've read that some need calibration through a proprietary MFD / display and some do not. I'm wondering what to look for as far as that goes.

Almost all speed and depth transducers are made by Airmar, and simply resold by the various instrument makers (Raymarine, Garmin, etc).

All transducers are by nature analog. Depth transducers require a driver that generates the sound pulse that makes sonar, sonar. Raymarine makes a analog/digital converter, their itc5, that converts depth, speed, wind and temperature signals to NMEA 2000 format, albeit with Raymarine connectors instead of the standard ones.

You might consider getting one of those and connecting it to your DST. It's simple to convert Raymarine to NMEA connectors.

[tradrockrat]

Originally Posted by sainted

All transducers are by nature analog. Depth transducers require a driver that generates the sound pulse that makes sonar, sonar. Raymarine makes a analog/digital converter, their itc5, that converts depth, speed, wind and temperature signals to NMEA 2000 format, albeit with Raymarine connectors instead of the standard ones.

So - Hypothetical here - buying the "Garmin" DST800 smart triducer and plugging it into the NMEA backbone is great, but depth wont read on my laptop / tablet Nav station without a Garmin instrument somewhere to calibrate and generate the sound pulse?

I'm just trying to figure out the simplest set up - I plan on adding an MFD to my cockpit and using a tablet / laptop down below on separate navigation programs (but connected to NMEA backbone for redundancy). If the MFD (in this hypothetical it's a Garmin) goes down, the depth transducer stops working?

Thanks

[cpt_757]

I believed eve new one will come out soon dst 810, has blue tooth capable to app on your phone or iPad.

[tradrockrat]

Originally Posted by cpt_757

I believed eve new one will come out soon dst 810, has blue tooth capable to app on your phone or iPad.

ooooohhhhh....the plot thickens. Thanks for the heads up.

[sainted]

Originally Posted by tradrockrat

So - Hypothetical here - buying the "Garmin" DST800 smart triducer and plugging it into the NMEA backbone is great, but depth wont read on my laptop / tablet Nav station without a Garmin instrument somewhere to calibrate and generate the sound pulse?

I'm just trying to figure out the simplest set up - I plan on adding an MFD to my cockpit and using a tablet / laptop down below on separate navigation programs (but connected to NMEA backbone for redundancy). If the MFD (in this hypothetical it's a Garmin) goes down, the depth transducer stops working?

Thanks

Airmar does indeed make the DST800. Since it is a "smart sensor" it has a brain and can be calibrated using Airmar's CAST app, which is available free for Android and iOS devices. I assume that compatible chart plotters can calibrate it as well. Presumably, once calibrated it will stay that way, so any device receiving data from it will report the calibrated data.

Sorry for the misleading comment and analog to digital conversion earlier. The DST800 already has that baked in, and has a NMEA 2000 interface. At least it'll be easy to test. If it won't talk to the CAST app, then it's likely dead. As someone else mentioned, you can easily replace the paddle wheel it that's all that's wrong with it.

S

[tradrockrat]

Originally Posted by sainted

Airmar does indeed make the DST800. Since it is a "smart sensor" it has a brain and can be calibrated using Airmar's CAST app, which is available free for Android and iOS devices. I assume that compatible chart plotters can calibrate it as well. Presumably, once calibrated it will stay that way, so any device receiving data from it will report the calibrated data.

Sorry for the misleading comment and analog to digital conversion earlier. The DST800 already has that baked in, and has a NMEA 2000 interface. At least it'll be easy to test. If it won't talk to the CAST app, then it's likely dead. As someone else mentioned, you can easily replace the paddle wheel it that's all that's wrong with it.

S

Thank you! I appreciate your responses.

[bcboomer]

Originally Posted by sainted

Airmar does indeed make the DST800. Since it is a "smart sensor" it has a brain and can be calibrated using Airmar's CAST app, which is available free for Android and iOS devices. I assume that compatible chart plotters can calibrate it as well. Presumably, once calibrated it will stay that way, so any device receiving data from it will report the calibrated data.
S

The Airmar CAST app says it is only for the DX900+.
Have you used it with the 800 series?

[smac999]

how would you connect a phone app to a nmea 2000 network?.... you can't

[Brewgyver]

Originally Posted by smac999

how would you connect a phone app to a nmea 2000 network?.... you can't

You can if you have an MFD that has BT or WiFi connectivity, or if you have a NMEA-WiFi gateway, such as from Digital Yacht, Quark, Actisense, etc. You can even do a homebrew unit built on a Raspberry Pi.

In other words, lots of ways to do that.