Any Data for Triducer versus single Transducer Speed Accuracy?

[WHK]

I'm helping a friend upgrade old sensors & instruments on his J/109.  He is replacing 15 year old NKE instruments.  The boat speed has always suffered from tack-to-tack speed accuracy and the corrections made aren't that accurate so we are moving the paddlewheel to the centerline.  I did this on my own boat and it really made a difference.  I plan on mounting an Airmar P217 housing (completely flush on the bottom with no mushroom) and fairing it smooth to the hull.  Since we can start from scratch on the transducer, I want to be sure that the most accurate and most responsive speed insert is used.  Depth accuracy is good enough for either the triducer ior stand alone, it is most accurate speed that we want.

Is there any real data available that compares accuracy and response of a Triducer with speed, depth and temperature to a stand alone speed and depth transducer?  It would not be a problem to keep the original depth transducer since it works fine, although we do plan on replacing the housing with the P217 similar to the depth in order to get a smooth faired surface.  Alternately, if there is no speed performance difference, the Triducer could be used.  I plan on using a NMEA 2000 smart sensor so the flexibility exists for future instrument upgrades.  How good is the data on the new Ultrasonic speed transducers?

P217 Housing

Airmar ST850 Smartsensor

Airmar DST800 Smartsensor

 

[Miles]

Not seen any real data from the companies, but did have the misfortune of sailing a 100ft Baltic with a triducer, we switched to SOG immediately.   The unit was crap and very noisy.

 

[Pelle]

I agree. That airmar triducer is, in my experience, pretty useless and I pretty poor experience of flushing the Airmar DST800 also. It became very very unlinear which I attribute to the small dimension of the paddlewheel compared to the boundary layer thickness

 

[WHK]

Doing some more online research I discovered that the data update rate for all the Airmar "Smart" transducers is 1Hz which is to slow.  I found the Garmin GST43 transducer (same as the old Nexus TH43) has a bigger paddlewheel.  It can be coupled with the Garmin GST10 analog to NMEA 2000 converter that outputs at a 5hz rate.  This can be bought for under $200.  Now all I need to do is find the 43mm flush mount housing and I'm good to go.

 

[sail69]

Just a thought...but Airmar is now selling paddlewheel-less speed sensors (UDST800).   One actually can determine leeway as well (DX900).  No experience with them but it would  be nice to get rid of the forever fouled paddlewheel

No I don't work for Airmar.

 

[WHK]

Just a thought...but Airmar is now selling paddlewheel-less speed sensors (UDST800).   One actually can determine leeway as well (DX900).  No experience with them but it would  be nice to get rid of the forever fouled paddlewheel

No I don't work for Airmar.

Thanks - I did see that but at an order of magnitude more expensive than a good paddlewheel, I don't know if I want to be a beta tester for this product.  If they want to offer it at the same price I can get the GST bundle combo, I would be happy to try it and report test results.

 

[WHK]

I have the T41 Triton on my boat as a single display added to the existing Nexus NX2 displays.  I added the T41 2 years ago so I had the wind strip charts visible while racing - it is very good for that.  I can put any data I want on the T41, but use the Nexus displays for all other data.  I have installed the B&G Tritons and Zeus 2 / Zeus 3 on other boats - all were done using the existing analog transducers through an interface, so I can't comment on the DST800 sensor.  Bottom line is when the sensor inputs are good, the displays are great.  Hence - the thread drift here is kind of the reason I started with the original post.  If you are serious about good speed inputs, I don't know if the Triducer is the way to go.

 

[LionessRacing]

If you are serious. Get Signet paddlewheels and NOT the "SMARTSENSORS" with  NMEA outputs which are not high update rates, and have difficulty in adjusting the damping. The bigger the paddlewheel and the better the install, the more likely your bottom speed will be accurate. 

Check on compatibility with your instruments whether you need Hall Effect or simple magnet/coil. 





Paddlewheel Sensors







Self-Powered Paddlewheel Sensor
 

  • RCA Plug with 35 ft. cable (for new traditional instruments)
  • AMP Plug with 35 ft. cable (for older knotmeters)
  • For SmartPak with 35 ft. cable (Conxall Plug)
 





1-2200.100-1 
1-2200.100-2
1-2200.100
 




$189
$192
$189
 


 

Open Collector (Hall Effect) Paddlewheel Sensor

  • Square wave output for non-Signet Marine Instruments. Call

 


1-2200.200


$189







or get the equivalent that are available from B&G: 

Get the blanking plugs and remember to remove the paddles between sailings

put a DT800 in the old hole and get depth/temperature... 

 

[Passport111]

Two years ago I put in a B&G system with triducer, wind sensor, and 3 T41s.  I removed a Signet system with the depth and speed sensor and three instruments.  

Unfortunately, I was ignorant of the fact the the existing Signet speed sensor (from this conversation) is probably better than the B&G/Airmar triducer that replaced it.  

This winter I have removed the old Signet thru hulls and plan to fill them in.  Now I'm wondering if I just put the speed sensor back in?  I did like the fact that I would have only one hole vs two but I have been very disappointed with the triducer thus far.  I never removed the Signet sensor over a season (on Lake Michigan) but the B&G fails/fouls several times a season and can be intermittent even after cleaning.

Thoughts on this?  How do I connect the Signet sensor to the N2K network?  Another Actisense?

 

[WHK]

Two years ago I put in a B&G system with triducer, wind sensor, and 3 T41s.  I removed a Signet system with the depth and speed sensor and three instruments.  

Unfortunately, I was ignorant of the fact the the existing Signet speed sensor (from this conversation) is probably better than the B&G/Airmar triducer that replaced it.  

This winter I have removed the old Signet thru hulls and plan to fill them in.  Now I'm wondering if I just put the speed sensor back in?  I did like the fact that I would have only one hole vs two but I have been very disappointed with the triducer thus far.  I never removed the Signet sensor over a season (on Lake Michigan) but the B&G fails/fouls several times a season and can be intermittent even after cleaning.

Thoughts on this?  How do I connect the Signet sensor to the N2K network?  Another Actisense?

I'm thinking of using the Signet with the Garmin  Garmin GST10 analog to NMEA 2000 converter that outputs at a 5hz rate.  That will tie to the NMEA 2000 bus with all your B&G stuff.  You could keep the triducer and just use the depth off it.  The B&G source menu should allow you to select the GST10 or the Tridcuer for speed input.  Just select the GST10 for speed and Triducer for depth.

 

[WoobaGooba]

I'm thinking of using the Signet with the Garmin  Garmin GST10 analog to NMEA 2000 converter that outputs at a 5hz rate.  That will tie to the NMEA 2000 bus with all your B&G stuff.  You could keep the triducer and just use the depth off it.  The B&G source menu should allow you to select the GST10 or the Tridcuer for speed input.  Just select the GST10 for speed and Triducer for depth.

Will that require a Garmin MFD to calibrate the Signet paddel wheel via the GST10?

 

[WHK]

I don't think a Garmin MFD is needed to calibrate it over the N2K network.  On another installation I was able to calibrate analog speed using a B&G Triton connected to a Raymarine ITC-5.  The Triton brought up the calibration menu option and sent the calibrated speed to the other Triton on the network.  The B&G Vulcan did not get the calibrated speed - B&G acknowledged the S/W limitation in the Vulcan when I called about it.  Worst case, I have a Garmin GND10 on my boat that I know will talk to it for calibration.

 

[WoobaGooba]

I don't think a Garmin MFD is needed to calibrate it over the N2K network.  On another installation I was able to calibrate analog speed using a B&G Triton connected to a Raymarine ITC-5.  The Triton brought up the calibration menu option and sent the calibrated speed to the other Triton on the network.  The B&G Vulcan did not get the calibrated speed - B&G acknowledged the S/W limitation in the Vulcan when I called about it.  Worst case, I have a Garmin GND10 on my boat that I know will talk to it for calibration.

Please let us know if you are successful. 

 

[Moonduster]

If you're concerned about accuracy at low speed, you need not bother much with the Airmar sensors. Signet is easy to deal with and will ship from stock. Getting through Australian customs isn't much drama if you call them before you order and follow their process so that they can find you when the parcel arrives in order to charge the (obnoxious) duty.

 

[Itsabimmerthing]

I was thinking about going from 2 transducers down to one triducer, asked B&G and they told me not to do it. Accuracy is not as good as with pure speed log only.

 

[WHK]

I was thinking about going from 2 transducers down to one triducer, asked B&G and they told me not to do it. Accuracy is not as good as with pure speed log only.

Is that the case on a monohull too if the xducer is mounted on the centerline?

Edit: nevermind - I reread and you are talking speed and depth separate.  Also the tri-ducer which based on comments here is not as accurate.

 

[WHK]

Now a related question - I received a comment about flush mount versus the "mushroom" mount.  The comment indicated that the mushroom was actually better because it projected the paddlewheel better into the water flow.  I was thinking that the flush mount wouldn't disturb the flow and provide more accurate readings in addition to the advantages of an overall faired surface.  Since I've taken the time to longboard the hull for a faired surface, it made sense that the flush mount would seem better.

Any comments on flush versus the standard "mushroom" housing?

Based on what I've gained from comments on the forum: 

• Triducer performance is not as good as a dedicated speed sensor
  
• NMEA 2000 Smart Transducer data rates are 1 sample per second on N2K bus - not enough for meaningful performance processing
  
• The Garmin GST10 provides analog to N2K conversion at 5 samples per second on N2K bus and seems to be a reasonably priced solution for performance processing inputs
  
• The best (most responsive) paddlewheel sensor is the Signet - blue top is the Hall effect sensor that should work with standard analog speed inputs on various manufacturers processors.  The Garmin GST43 is a close second with its large paddlewheel. Both the Signet and GST43 are analog Hall effect sensors.
  

I am going to get a Garmin GST10 analog xducer to N2K adapter and check it with the boat on the hard to confirm that the B&G Triton brings up the speed calibration menu.  I have previously done this with a Raymarine ITC-5 so I am confident this will work.  I will document the GST10 wiring color codes so when the analog xducer connector is cut off the sensor connections are known.

 

[Passport111]

WHK,  thanks I'm really interested in what you find.  I have the red top Signet speed sensor.  Is this self powered?

If the Signet works with the Tritons I may very well put the speed sensor back in and just fill the one hole for the old depth and as you say just leave the triducer for depth and water temp.

 

[WHK]

WHK, will keenly await your results.......!

GST10 is on order so should arrive for testing late next week.  Boat is on the hard but we'll be able to do communications tests and determine if the calibration menu is visible on the B&G displays. 

I also sent a message to Garmin tech support asking for the pinout / color code on the analog side of the GST10, since it isn't in the GST10 manual.  I did some research on the Airmar cross reference page and found the pinout for the Airmar T80 temp sensor that Airmar makes for Garmin and can plug in to the GST10.  Here is the analog connector pinout.  Pins 1-4 on the 8 pin connector are used as follows: 1 - Shield/Ground, 2 - White/Temperature, 3 - Green/Speed Sensor, 4 - Red/+ Voltage Speed