How to calibrate a paddlewheel speed transducer?

[Cliffhanger]

I upgraded some of my boat's chartplotter a while ago to an Axiom 9 but didn't have a paddlewheel so no Speed Through Water (STW) and thus no true wind speed. So I installed a DST800 with NMEA2000 output to solve the problem. The trouble is that I can find no way to calibrate the STW and it is currently about 20% less than Speed Over Ground. The depth is also unable to be calibrated so I am still using an old NMEA 0183 transducer. You would think that an expensive bit of kit like the Axiom would have a few lines of code to calibrate inputs......

FYI, I also have ST60+ wind and ST6001 autopilot plus a Quark QK-A032.

Can anyone help me here? What other kit do I need to buy to get this working?

[Pandor]

The calibration for DST800 isn’t done through the Axiom. You do it through the sensor app itself.

[Sailmonkey]

Originally Posted by Pandor

The calibration for DST800 isn’t done through the Axiom. You do it through the sensor app itself.

My understanding is that the dst810 is Bluetooth, while the 800 needs offsets applied through a plotter or multi display interface.

OP, I suggest you contact raymarine support about this, they’re pretty quick with a response.

https://raymarine.custhelp.com/

[OldGreyB]

Having just replaced my faulty DST800 with a new DST810 my understanding is:

Basically the Axiom 9 MFD will only calibrate the directly connected 3D transducers with CHIRP DownVision, RealVison 3D etc.

Incredibly the Airmar DST 800 needs its offsets applied via an instrument display, it can not calibrated via the Axiom MDF - depsite the Airmar transducers being a standard OEM transducer to the Raymarine systems. The newer DST 810 is bluetooth enabled and offsets can be applied via the downloadable Airmar App "AirmarCast"

The bad news is well written here on this Raymarine Answer thread: https://forum.raymarine.com/showthread.php?tid=5971

My current understanding is you will need to procure a multifunctional instrument display such as an new Raymarine i70S, or an older 70 Tridata or similar, connect to your SeaTalkNG / NMEA 2000 network, and calibrate from there.

If others have another proven solution - then lets here it.

[OldGreyB]

For those following this thread, this may be of interest: Unlike the OP, due to supply chain issues I could only procure the DST810 with the additional capabilities that I didn't really need, (Bluetooth, Tilt, Heel) at additional cost. Additionally I could not find any OEM DST810 documentation that shows the dimension of the actual transponder, only the thru hull dimensions are shown. On arrival, it is the same dimensionally as the DST800, and fits the existing thru hull ,good on you Airmar.

As a cautionary note for others, I found on my Seatalk NG® system, the Circa 2010 Raymarine ST70 Mulifunction display would recognise and calibrate the offset on the DST800. However it does not recognise the DST810. Luckily I also have recently installed new Raymarine i70S's, which do recognise the DST810, so I can calibrate offset from there or via the Airmar APP.

[CarinaPDX]

Calibration is basically a disaster area for marine instruments. With older systems the calibration was done in the instrument heads or chartplotter (MFD), and any data sharing was done over 0183 after the corrections were made in the parent head or MFD. With the advent of N2K Airmar has had the ability to put the calibration in the smart transducer but MFD vendors have been slow to support it. Raymarine was one of the first to support calibrating speed from the MFD, including different corrections for selected speed ranges. I am shocked to learn that they have dropped this in favor of supporting proprietary products. At one point Maretron and Airmar agreed to support calibrating each others' sensors with their products, and the Maretron multi-displays will do the job as well as the RM i70. If only all chartplotters supported calibration in-sensor we would all be very happy, but that is not the case. However, there is a simple solution: download Airmar's Weathercaster software, which works with Windows 10 and several USB-N2K adapters, including the Activision one that I have. This software allows for calibrating sensors, including depth, speed, and temp among others, as well as changing other parameters such as reporting frequencies. The only fly in the ointment is that it is not currently supported for Windows 11 [edit].

Greg

[CarinaPDX]

Originally Posted by CarinaPDX

including the Activision one that I have.

I slipped a gear here. It is the Actisense NGT-1 USB adapter. Obviously been playing too many games...

Greg

[MJH]

Originally Posted by Cliffhanger

I upgraded some of my boat's chartplotter a while ago to an Axiom 9 but didn't have a paddlewheel so no Speed Through Water (STW) and thus no true wind speed. So I installed a DST800 with NMEA2000 output to solve the problem. The trouble is that I can find no way to calibrate the STW and it is currently about 20% less than Speed Over Ground. The depth is also unable to be calibrated so I am still using an old NMEA 0183 transducer. You would think that an expensive bit of kit like the Axiom would have a few lines of code to calibrate inputs......

FYI, I also have ST60+ wind and ST6001 autopilot plus a Quark QK-A032.

Can anyone help me here? What other kit do I need to buy to get this working?

I'll let others answer the hardware side of your post.

Calibrating the paddlewheel Speed Through Water. If the boat is moving on a windless day (motoring) and motionless body of water it should read the same as your GPS. Otherwise, it is the culmination of tide and wind affects.

I'm currently doing the same thing with my Datamarine Link 5000 (1980s era) system...still running great. As previously noted the calibration is on this unit itself. As far as the procedure goes the manual says to use a set course of 0.5 to 2.0 miles under relatively calm wind and current conditions (good luck), making timed runs in both directions (seconds) using the same typical cruising power setting. Then calculate your speed for each run, average the two run times to get your speed, then run the course one last time and do the calibration to the average you calculated.

On my previous boat I would calibrate the unit (different manufacturer) by motoring the boat through a USCG one-mile course printed on NOAA paper charts not far from my home but the new charts are no longer showing the course and the markers on shore have become overgrown with vegetation.

The instructions ends with: "Note that the instrument calibration will be affected by progressive fouling of the hull. The boundary layer will effectively increase, and the instrument will indicate lesser speeds than when originally calibrated. The proper remedy is hauling and cleaning the boat's hull."

As for my calibration I'm about to get the boat hauled and bottom cleaned. Afterwards, I'll try to find a calm day at slack tide and use my GPS reading.

How many owners do you think have calibrated theirs?

Good Luck with your calibration.