Do transducers break down ?

[OldManMirage]

I have a pair of somewhat working Datamarine speed and depth instruments. I have spoken with the folks at DMI Marine and they can rebuild the actual instruments, which is great because I think they could use new LED displays at the least. I don't know the cost but I think I'll make another phone call and find out.

The depth sounder does not want to work well. It is somewhat erratic in it's operation, often giving depths - both too shallow of deep - that I know are incorrect.

My question is how much of this could be the transducer ? Do they break down over time ? Or is it more a case of they either work or not ? I can understand how the display head might not be sending enough signal to the transducer or not reading it correctly because of a fault in the electronics. But how about the transducer itself ?

And I have cleaned the bottom, so there is no interference from that sort of thing. No bottom paint, no barnacles.

Thanks.

[muttnik]

Not being an electronics expert I can't reply on a technical level but I can relate my experience with the 30-year-old autohelm/airmar depth unit. Having not used the boat through lockdown, when I came back to it last year, after hauling out, antifouling and putting it back in I noticed depth was reading 1.5m whatever the depth was. I later learned that this was the minimum depth an old ST50 can measure, plus the depth offset I had set. Pins on the connectors looked ok. Squirting contact cleaner and plugging and unplugging a few times seemed to improve things: reading was ok over about 8m but either 1.5 or constantly varying in lesser depths (e.g. moving up and down between 4.5 and 2.5m).

Spoke to my local electronics shop who told me "it's always the transducer" and said these things has a lifetime of about 10 years. Convinced, I bought a new transducer but with a freshly anti fouled bottom I decided to wait a bit to install it. Meantime I tried dangling the new transducer in the water and hooking it up to the head. Same result. So it's the head! Sent the head off to another electronics company to be assessed but it came back with no fault found.

Convinced the original electronics company to test the head and the transducer they'd supplied me. They came back and said the head seemed to be faulty but I should change the transducer too.

So my local electronics people are very confident that transducers last a lot less than mine appears to have done and yes, it's an unreliable reading rather than none at all. I've had this advice backed up by another installer who advocated putting in withdrawable transducers so you don't have to lift the boat when one fails. But clearly in my case there's something iffy with the head even though the company which originally tested it said they had measured its outputs well within acceptable parameters.

I'm now looking at buying a new and horribly expensive raymarine i50. It'll be interesting to see if the old "faulty" transducer works with it

[Mike OReilly]

I had a depth transducer die on me. It was a slow death. Started giving faulty readings occasionally. The frequency grew over many months, to eventually giving more false measures than true.

I replaced it with a new transducer, and connected it to my old display. All was well.

[Rumrace]

I’ve had senders fail never an instrument. I cut one open and the wires past the potting had corroded I think senders have a half dozen ways to fail while a gauge has one.

[hugosalt]

I have a spare Datamarine depthfinder display head in for repairs at DMI now.
Rates are $75. to look at, thinking minimum to repair at $150.
See their web site under services as rates are all spelled out.
I have current transducer installed inside hull for about 25 years now. Working well.
Original thru hull transducer only lasted 6-7 years.
Have installed a back up (in hull) transducer to switch over in case needed. Cheap, Easy.

[sailorboy1]

My depth sounder, meters, and chart plotter are 21 years old and still working

[deblen]

Before buying a new different brand "head" ,verify the frequency (200,50,?) of your existing head.
If your new brand/model head is the same frequency as the old head,the new head MAY work with the old existing transducer-because the head & transducer are matched to the same frequency. Do not expect a 200kz head to perform well(or at all) on a ducer of different frequency.


Next-some older cheaper depth only units used a 2 wire ducer cable without a braided shield. Discard these when they start acting up.


Ohmmeter the 2 depth transducer wires in the cable(usually blk & wht or red & blk). Should read open(Infinity).
Ohmmeter each depth wire to shield & each other wire(temp,speed) to shield in turn.
Should all read open. Repeat for the other depth wire.



If your existing ducer has a braided shield,this shield,if broken/corroded/allows interference from other electrics to penetrate the 2 working wires of the cable,causing intermittant operation. To check the continuity of the shield requires putting one ohmmeter probe in the shield wire pin hole at the head plug & the other wire to the shield close to the ducer.This will require piercing a hole in the plastic cable covering to expose the shield.This pierce should be as tiny as possible & resealed with a good marine sealant.


If you have a combi ducer with depth,speed & temp all in the same ducer,there will be a 5volt powered IC temp "chip" potted in the ducer.It is not uncommon for seawater to get to this chip,causing various problems. You can cut the 2 temp wires at or inside the head to eliminate.


Transducers are made of 2(or more) quartz crystal pucks,with a depth wire affixed to each one & potted in the ducer body. These quartz pucks flex each time they are hit with a pulse of energy-many millions of times over their lifetime-so ,yeah,they can get "tired" & less sensitive.


If you require depth only(no fish finding,bottom density/composition etc.) a simple,relatively inexpensive 200khz digital depthfinder with inside hull mounted ducer is likely all you need.


Cheers/Len


https://forums.sailboatowners.com/th...ounder.139786/

[Oeanda]

Interesting. Two of our three sounders are prone to going nuts once in a while. Hence adding a third with better display… They’ll act as if we are steadily getting deeper or (more nerve-wrackingly) shallower. It’s stressful watching the numbers as the bottom apparently comes up at you.
We haven’t gotten around to dealing with the issue yet other than to poke and prod, but I’d assumed (hoped) that the transducers were the last likely culprit.

[wingssail]

Our signet depth sounder transducer failed after about 6 years. I had a spare which I installed and it has worked perfectly since then (32 years). I have another full spare which I loaned to a friend who's instruments got fried in Papua New Guinea. He since returned it and it works. But I noticed that the display of both of them are hard for me to read. I don't know if it is the Signet or my eyes. Can't hear the alarm very well either. Oops that's a clue.

But, moving on, we also have a Lowrance with two sounders, 50khz and 196khz. They have been installed and working since 1993 but seem to have lost a little power.

So that's three depth sounders pinging away all the time. Must entertain the whales.

If you have multiple sounders they must be on different frequencies or they will get cornfused (Oenada, is that you?). My Signet is 200khz so that fits with the Lowrance.

My new B&G has depth sounder built in and when I install the speed & temp maybe I'll put in the depth sounder transducer for it too; I'll have a quartet I have to check the frequency.

Call me depth sounder obsessed (I have an 8 foot keel and like to play the beach) but no new technology stuff, too bad.

By the way, all of these transducers are shooting though the hull (glued inside with a dab of silicon).

[Oeanda]

Originally Posted by wingssail

Oeanda, is that you?

….By the way, all of these transducers are shooting though the hull (glued inside with a dab of silicon).

Hmmm. Interesting tip, thanks. It’s not a rabbit hole we have really poked our head down yet. But those transducers have been there a long time previous to us so I have to assume (or do I…) that the setup was working at one time.

Out of curiosity, where on the hull are your transducers stuck? Maybe a stupid question. But I assume you probably don’t want them above the keel.

[hugosalt]

Hate to admit but I siliconed my transducer in about 25 years ago also. Sure there are better adhesives/sealers.
I located mine as far forward and as level as I could. (correct not over keel)
First using a bag of water between hull and transducer to test location as must have no voids to get a reading. No voids: no good on cored hulls or in a spot with a void.
Have to prop in place when setting.
Sure, years ago, was much discussion on CF and other forums on various installs.
Easy search should reveal.

[wingssail]

Originally Posted by Oeanda

Hmmm. Interesting tip, thanks. It’s not a rabbit hole we have really poked our head down yet. But those transducers have been there a long time previous to us so I have to assume (or do I…) that the setup was working at one time.

Out of curiosity, where on the hull are your transducers stuck? Maybe a stupid question. But I assume you probably don’t want them above the keel.

No of course not above the keel. Our keel has about an 8' chord at the root. One transducer (the Signet) is mounted on the centerline about a foot ahead of the keel, the other two are just either side of the centerline aft of the keel near the transmission. Our bottom is pretty flat in those areas so it works well. If I mount the B&G transducer it will be a little forward of the Signet one.

I recommend placing the transducer in the spot you might consider mounting it with some water (a puddle) and see of it works. You can also dangle it over the side of the boat to compare how well it reads in deeper water and compare that with the inside reading. In Puget Sound we went out to 600ft and tested the transducers before permanently placing them. By adjusting the sensitivity we found that the inside (shoot through the hull) was about 10% less effective than outside, (which presumably would be similar to a through the hull mounted transducer.) It was worth it to me not to have holes in the boat or anything in the flow (drag).

[Celestialsailor]

Originally Posted by OldManMirage

I have a pair of somewhat working Datamarine speed and depth instruments. I have spoken with the folks at DMI Marine and they can rebuild the actual instruments, which is great because I think they could use new LED displays at the least. I don't know the cost but I think I'll make another phone call and find out.

The depth sounder does not want to work well. It is somewhat erratic in it's operation, often giving depths - both too shallow of deep - that I know are incorrect.

My question is how much of this could be the transducer ? Do they break down over time ? Or is it more a case of they either work or not ? I can understand how the display head might not be sending enough signal to the transducer or not reading it correctly because of a fault in the electronics. But how about the transducer itself ?

And I have cleaned the bottom, so there is no interference from that sort of thing. No bottom paint, no barnacles.

Thanks.

The short answer is YES! Not only do they break down over time (sounder or readout), you can also get a dud when buying new like I did with the SITEX, POS.

From day 1, erratic readouts. then a week of no problems, then back to depth read-out hell. I call them and get..."Oh must be the read-out." Send the old one in and 5 weeks later after they receive it another one finally arrives two weeks before I leave for Mx. Works ok for a few days, then screen goes blank. Next morning reappears. I call them back and tell them and get..."Hmmm never seen that before,,,you might want to scrub it". Eventually try another read-out and the usual 5 week wait and return home, take the new, new one down and same thing.

I call again and tell them it must be the transducer. I'm told it is out of warranty. I'm pissed! After major whining on my part I get a reduction in price on the transducer. Next haul-out it is replaced. I call them again and say,"Well now that we know it wasn't the readout, but the transducer, should I be refunded the money for the transducer since it was the problem from day 1?" ...No was the reply.

Sure do like my Furuno and Garmin stuff on the boat I have now.

[Oeanda]

Originally Posted by wingssail

No of course not above the keel. Our keel has about an 8' chord at the root..

Ah I see. In our case that may only leave a small spot up in the bow as a keel-free option. A good spot for it though, aside from the rather long wires. When I spent a millisecond looking at it previously, the chine made it look awkward to perch a transducer inside in a way where we could gain some separation from the keel, and left me scratching my head. But, time to do some proper research obviously. Thanks guys.

[rslifkin]

Originally Posted by Oeanda

Ah I see. In our case that may only leave a small spot up in the bow as a keel-free option. A good spot for it though, aside from the rather long wires. When I spent a millisecond looking at it previously, the chine made it look awkward to perch a transducer inside in a way where we could gain some separation from the keel, and left me scratching my head. But, time to do some proper research obviously. Thanks guys.

They make transducers with an internal tilt to account for hull deadrise. Depending on the angle, using one of those may allow you to put the transducer off to the side and still get a good reading.