depthsounder question

[jim rosenthal]

I'm having trouble with my Standard Horizon depth sounder; this is a free standing unit which is coupled only to a repeater at the downstairs helm. The problem is that it reads erratically- sometimes I get accurate depth information, based on local knowledge and chart soundings, other times I get nonsense info (2600 feet in Chesapeake Bay is unlikely) and sometimes I just get horizontal lines, which I guess either means no water or it can't interpret what it's getting. What I can't figure out is whether this is a transducer malfunction or the head unit which drives the transducer.

These operate on 230kHz. My other unit, part of my Northstar 6000i system, is set to operate at 50kHz so they don't interfere with each other; in the past when I operated that one at 200kHz, they seemed to be messing up each other's readings.

The transducer is not fouled, and the voltage supply is consistent. I don't mind replacing any part or all of the system- I'd just like to figure out, if I can, whether it's the transducer, or the head, or both, that's the problem. I would like to avoid a midseason haulout if I can.

Airmar still makes a transducer for this unit, btw. And they have suggested I avoid in-hull transducers as the hull is about 25mm thick at that point. If it needs to be replaced, they recommended another transducer in the hole that is already there, which is 2" wide. That does limit things a bit, since I'd have to find another transducer with a 2" threaded barrel- that or close the hole entirely and redrill it, if I went to another make of sounder and a different transducer.

All suggestions appreciated.

 

[bobk]

My Humminbird began doing the same thing on the way south last year. Tech service tried to trouble shoot by phone and decided I needed a new transducer. I replaced it at a haul out and all is well. My diver said he has done these in the water, but I was a bit chicken, especially since Airmar warned me that any water that might enter the plug was likely to shorten its life.

Bobk

 

[MikeP]

"(2600 feet in Chesapeake Bay is unlikely) "

Hmm, I wonder if Jules Verne was wrong when he postulated that the way to the center of the earth was via the crater of Sneffels Yokul. It may be via the Rosenthal Deep right there in the Chesapeake Bay!

Re depth finder transducers...if you are considering an in-hull, FWIW, our second depth finder is a Raymarine ST40 with an Airmar P69 in-hull which transmits through the hull of our 53 with no issues at all and tracks perfectly with the through-hull transducer that feeds our Garmin chartplotters. I installed it 4 years ago and it has worked flawlessly...unlike the Garmin depth finders which have failed on several occasions but that's another story.

Of course a through hull is much better if you are looking for fish-finding resolution but if you just need depth, the in-hulls work great - at least to the max depth w have seen in the Ches. (I doubt they could get a reading at the Rosenthal Deep.)

 

[jim rosenthal]

I'd like to get through this season and replace this one this coming winter if I can. Does the Raymarine 40 use 230kHz, and can it drive multiple displays, do you think?

 

[MikeP]

The ST40 operates at 200KhZ and the P79 operates at 50 or 200. I have never had any interference between the ST40 and Garmin Chartplotter depth reading. The transducers are located maybe 5 feet apart though on opposite sides of the keel (one in each engine room).

You can do multiple ST40's with just a Raymarine cable between the two ST40s - I didn't know that myself until someone on this site told me that earlier this year because I've been meaning to add a 2nd ST40 so as to have back-up depth at both helm positions. I thought I would have to add another transducer but it's easy to run a 2nd ST40 as a repeater.

 

[Boatnut]

If the transducers are too close together they can still interfere just by over powering the receiver circuit, in which case frequency has nothing to do with it. It is just like driving close to a radio station, and you are listening to a different station but also get the one you are close to.

 

[jim rosenthal]

I do't have the beam that Mike has; my transducers are only about six or seven feet apart. But as long as they are not set on the same frequency I don't seem to have that problem. I think either the head unit is not powering the transducer consistently, or the transducer itself is not working all the time. Very frustrating. If I knew it was the transducer, I'd just bite the bullet and order a new one and do a haulout and replace it. But I don't know, and just replacing it with another one that may not work with the next generation of electronics seems like a bad idea....

 

[SeaEric]

Have you tried disconnecting the repeater display to see if that makes any difference?

I just added an in hull transducer for my Garmin CP and it seems to work perfectly. The hull of my 1966 41 TC is most likely as thick as your 36C. If you have depth capability on your Northstar and the Standard is merely a back up, why not wait until Winter haulout?

 

[rsmith]

Transducers get weak with age. It's kind of like developing cataracts. I read some where 5 years is about the lifespan for a xducer.

 

[jim rosenthal]

Well, it is definitely older than that. I think if I can get through the next few months with it, I will replace it in the fall after she's hauled. And if I need new heads for it, well, I'll do that, too.

 

[SKYCHENEY]

Hmmm.... Both of my 1985 Datamarine 120khz transducers work just fine. There's only about 36000nm of bottom that's passed by them, so maybe they're just getting broken in.

 

[Boatnut]

Transducers are a lot like black magic. Some will last forever, some have very short life. A transducer is basically a crystal, when you bang it with an electrical pulse it vibrates, when the signal returns it also makes the transducer vibrate, the time it takes for the sound wave to go to and from the bottom is divided by two then converted into distance. One of the biggest enemies to the transducer is shock, like something in the water hitting it. Another is a stupid move I have seen in a boat yard is some dummy hacking away on the transducer to remove barnacles.

 

[MikeP]

Jim, it's probably not applicable to your unit but my Garmin 3010C chartplotters stopped reading depth randomly last year. I couldn't figure out the problem and, after doing some internet searches, I discovered there was a known problem with them when the depth was set on "automatic," which they had been since new. I read a tech post that said to take it off auto and manually set the depth. I did that and they units have been fine since then. The manual setting does not limit the depth reading, it just changes the scale of the readout if the sonar page is viewed. I would have never found this info had I not searched the internet. Garmin makes no mention of it anywhere. I have no idea why they worked fine on auto for years and suddenly began having a problem but it happened after a fairly recent firmware "upgrade."

Again, probably not relevant to your depth finder but one never knows about electronic devices... maybe some sort of "reset?"

 

[jim rosenthal]

I'll try that. I don't think it has automatic ranging, it's too primitive for that, but I'll check. Good idea.

 

[jim rosenthal]

I ordered a new transducer, after finding out from Standard that I was wrong about the kHz spec on the unit I have; it is 200 kHz, not 235. So I'll replace the transducer; if it isn't that, the new transducer will work with any one of a number of replacement modern head units and repeaters. If I have to get a new head for it, I can get a Ray or a Garmin or a Furuno and it will work with any of them. Now I just have to decide whether or not to do a haulout midseason or wait til the fall. I am inclined to wait; we'll see if she lets me.