I've had nothing but problems with the prior AIRMAR DST800 triducer on my boat.  Initially it was depth issues.   Reading the torpedo keel rather than the bottom.    Not having depth at all.   Off and on functioning.

AIRMAR helped me replace the DST800 with the DST810.   Supposedly the issues with the prior model were addressed.   It was functioning fine until the other day when I lost boat speed.   Depth works fine.   Sea temperature works fine.  

OK.   This is just the usual case of sea grass or some other crud wrapping itself around the paddle wheel.   Just clean it, right?     Wrong.   Cleaned it and its still missing boat speed.

OK.   Lets do some diagnosis.      Take the unit out again.    Have someone spin the paddlewheel while I look at the data for the unit on the NMEA bus.   Guess what?  It provides speed when the paddle wheel is spun.   Hmmmm...  

OK... so maybe the flap that prevents *MOST* of the ocean from entering the boat has somehow jammed the paddle wheel when inserted?   How can you check this?  I have a long cable underwater camera that I can put on a stick to examine it.   I could dive on it with snorkel and mask... etc.

Or.... maybe there is something wrong with the unit once inserted.   Like some kind of growth or debris stuck immediately in front of the paddle wheel?    Unlikely since the boat was freshly painted and launched less than a month ago. 

Anyone have any ideas?   Has this happened to anyone else?    I'd be inclined to think its something physical/environmental blocking the paddle wheel but the DST810 has a bad reputation like the DST800, so I thought I'd ask.

This is where I am now.   

It would be boring if everything worked and kept working on board. What would we do with our spare time. 

Our paddle wheel often gets stuck - caused by marine growth after being at anchor or in a marina for a period. I normally snorkel on it and clean it and make sure it spins freely. Sometimes when I snorkel on it it doesn't take much force to get it spinning. Just a flick of the finger often frees it up. If it spins freely when out of the water I could only think 1. the sensor is not fitted with the paddlewheel fore and aft - if sideways or say 45 degrees off it will not work - but I can't see you fitting it incorrectly. 2. there could be some growth in front of the sensor which fouls the paddle wheel.  3. maybe the sensor is not pushed all the way in and not flush with the hull - again can't see you making this mistake. The test would be get the mask and snorkel out and jump in to have a look  - also spin the paddlewheel whilst on snorkel and see if it registers speed on the system. I gather the sea water up your ay is not overly warm? 

After we hauled out last time our sensor wasn't working - I snorkeled and found the shipyard had not removed the masking tape. 

Thanks for the comments.

a.   its been cleaned regularly.

b.   there is an arrow on the unit that is always aligned fore-and-aft when reinserted.

c.   Sea water is 52 degrees fahrenheit

The only way to examine it and see it spinning while inserted is to dive on it.    That will have to wait I suppose..

Rick

I had problems with the log. Pulling out the sensor and cleaning it did not help. Sailing at rough sea brought some reading back, but not accurate. Realized the root cause, when the boat came out of the water for winter storage: not only the sensor itself has been fouled, the barnacles were growing on the plastic ring of the casing holing the sensor as well and the small wheel didn‘t see any/sufficient current. Adding some antifouling on that plastic ring helped. 

https://www.airmar.com/Product/UDST800" rel="nofollow - https://www.airmar.com/Product/UDST800

OK.    Problem solved (for now).

It was what I thought.   At least when I executed on my theory the result was success. :-).  

Apparently the rubber flap that prevents the ocean from entering your boat while you pull the DST810 and replace it with the dummy somehow caught and caused a flow blockage.    By making sure the flap stayed out of the way while replacing the DST810 it seems to have avoided the problem.     

I'll be looking for this in the future, but the unit is working at this time. 

Mark

Never tried that - but the specs on the app don't include the 800 either. 

Not getting a half gallon of water in the boat every time the paddle wheel fouls is a real advantage. Then a few years ago, I had the flap on the thru hull fall out, which made cleaning the paddle wheel even more interesting. 

These don't seem to get fouled. Pricey but worth it. 

It also sounds like its thru-hull compatible with the DST800 and DST810.   In other words, "same hole in the boat works..."

Its gone bad again.    So much for the fix.      I contacted AIRMAR.   They asked for the serial number and said "we'll replace it". 

Usually, when the support team you have first contact with has the authority to just replace things, its a problematic device and they know that its easier to replace than to find out why.

One more update:

When I spoke with AIRMAR,  I asked them "what would make the replacement any more reliable than the original DST810?".   Was there some firmware update or bug fix that addressed the issue?

The answer I got was that during COVID, they had to switch suppliers for specific components to meet manufacturing needs.   This supplier has been the common thread for all the units at issue.    Thus the serial number check.   Apparently, they have now gone back to the original supplier.

We'll see. 

I have had issues with my Airmar 800 and have also found that it gets fouled very easily.I also found that the cable that connects to the backbone has a metal connection joint which over the years has become severely corrode.This has been replaced.However I have now gone with the UDST 800.My research told me that it was unreliable when first introduced due to being sensitive to voltage drops.However I am looking forward to years of good service from my new one.There is an electronic box to install but it is all plug and play.

Duncan