Can a dirty bottom prevent depth finder from working?

I have owned my Californian for three weeks now, and one by one, we are getting all the systems running, ie: generator, furnace, winlass and numerous other odds and ends.

I have a question re: the depth finders. There are two on the boat and neither work. One is old school, with large yellow/orange readouts (head end at helm with remote view at flybridge) The other is a 15 year oldish fish finder. The head end on both of these systems power up, but they appear to get no signal from transponders, as they don't register any depth. My boat has sat in the same covered slip for five years. Can algae and a dirty bottom prevent the transponders from working properly?

Thanks,

sam

I suspect not, because most transducers can punch through solid fibreglass bottoms rather well. However...I am hoping I am wrong, as the only depth-sounder on my boat with a thru-hull, which I moved to the flybridge when I put a new GPS/sonar combo in down below, and has worked faultlessly until now, but with the surface of the screen getting progressively more cloudy and hard to see through, until virtually unreadable, has suddenly stopped. I had a brainwave, and took a punt and took it home and cleaned up the screen beautifully with marble paste ceramic stove top cleaner, but when reconnected, "the lights come on but there is no-one home", as they say. (Well that saying is sometimes used to describe severe Alzheimers, but seemed to fit here as well). Now I admit to caressing the bottom just as we entered the marina last outing on Easter Monday, so I am hoping a big gob of mud is the problem, but bearing in mind the new Combo I mentioned fires thru the hull, and works fine like that, I am not holding my breath. But how typically frustrating is that? It was a great old sounder (Lowrance x70A) and all I needed up top. I have a handheld GPS for up there. I fix one issue nicely and then the damn thing dies on me for some other reason. Yes I was careful not to get any gunj into it while cleaning with the paste, but they are supposed to be waterproof anyway, and I've cleaned and reconnect and checked all connections several times. I am deflated - b***dy Murphy's law again, I bet...

Sam and PeterB I sympathise. About 2 and a half years ago I fitted Gemma with an integrated Raymarine nav, radar, GPS, autopilot and depth guage/fishfinder. Cost a mint. Ever since I have had it the depth guage gives up the ghost intermittently but of course with Murphy's help most often when I'm in shallow water - just when you need the damn thing. Ive checked the cable integrity, updated the software and even installed a reset switch just for the depth guage so I dont have to reset the whole system. Yet it just froze again last week end. Arrgh!! My supplier has exhausted his knowledge and is now going back to Raymarine for ideas.

I dont think external hull growth could have a major effect either. So frustrating....

Sam said:

I have owned my Californian for three weeks now, and one by one, we are getting all the systems running, ie: generator, furnace, winlass and numerous other odds and ends.

I have a question re: the depth finders. There are two on the boat and neither work. One is old school, with large yellow/orange readouts (head end at helm with remote view at flybridge) The other is a 15 year oldish fish finder. The head end on both of these systems power up, but they appear to get no signal from transponders, as they don't register any depth. My boat has sat in the same covered slip for five years. Can algae and a dirty bottom prevent the transponders from working properly?

Thanks,

sam

Click to expand...

Yes, a fouled transducer can be an issue.

From Lowrance's website..
Periodically wash the bottom of the transducer with soap and water to remove any oil film or growth that may collect. Oil and dirt reduce the transducer's sensitivity and can even prevent its operation.

Greetings,
I've heard one should NOT anti foul a transducer as even the layer of paint will reduce sensitivity as Mr. psneed alludes to. That being said, I've had success with mounting a transducer (Garmin 540S) to shoot through the hull with good results. As I have never had this unit operating with an external transducer, I have no comparison with resulting sensitivity. I suspect the hull is upwards of 3/4"+ thick and is solid glass.

There is special antifouling paint available for ducers (usually water based so the solvent doesn't harm the epoxy in the transducer)...that being said I have seen numerous tranducers accidently painted that have worked just fine and lasted their normal life.

It's all about sound waves, density and continuity of the material...if you internally mount a ducer and it shoots through solid glass or a liquid ...the time difference is so small that it doesn't affect performance that much. Try and shoot through a cored hull or a bunch or different density growth on your ducer and you get some inaccurate readings if any at all.

Sam said:

I have owned my Californian for three weeks now, and one by one, we are getting all the systems running, ie: generator, furnace, winlass and numerous other odds and ends.

I have a question re: the depth finders. There are two on the boat and neither work. One is old school, with large yellow/orange readouts (head end at helm with remote view at flybridge) The other is a 15 year oldish fish finder. The head end on both of these systems power up, but they appear to get no signal from transponders, as they don't register any depth. My boat has sat in the same covered slip for five years. Can algae and a dirty bottom prevent the transponders from working properly?

Thanks,

sam

Click to expand...

If you clean the transducers, you can eliminate fouling as a source of the problem. This may be the easiest troubleshooting step.

rwidman said:

If you clean the transducers, you can eliminate fouling as a source of the problem. This may be the easiest troubleshooting step.

Click to expand...

This.

Fouling does degrade signals, but normally you won't notice it unless you're running the type of equipment that needs a precision titanium sphere to calibrate it. If the barnacles are thick enough to make your signal erratic you've got more immediate problems.

Ok, well the above posts give me some hope the sudden failure to transmit of my Lowrance, that was working fine, but barely visible through a worn and cloudy screen front, and stopped working just when I thought of a way to clean the screen with fine marble paste, might just be because we kissed bottom the other day coming in. A sticky mud gob on it will wash off next time we go out and power up. We'll see, I guess...

Peter B said:

Ok, well the above posts give me some hope the sudden failure to transmit of my Lowrance, that was working fine, but barely visible through a worn and cloudy screen front, and stopped working just when I thought of a way to clean the screen with fine marble paste, might just be because we kissed bottom the other day coming in. A sticky mud gob on it will wash off next time we go out and power up. We'll see, I guess...

Click to expand...

If you have a transom mount transducer and hit bottom (or anything else), it may have gotten tilted do it no longer faces directly down towards the bottom. That can cause incorrect or no readings.

No, not this one Ron, it's my only sounder, ( I run 3) which has a proper thru-hull about midships on the starboard side. The newest shoots thru the hull on the other side from it - different frequency, and I have an old seafarer which runs on a different frequency again which is in a mineral bath type housing attached to the inside of the hull also. So I can normally run all 3 at once without interference. This one used to work the best, so I hope it is just mud on it. Especially as I could now see it properly, the marble paste worked a treat cleaning up the face - wish I had thought of that yrs ago. Time will tell.

Peter B said:

No, not this one Ron, it's my only sounder, ( I run 3) which has a proper thru-hull about midships on the starboard side. The newest shoots thru the hull on the other side from it - different frequency, and I have an old seafarer which runs on a different frequency again which is in a mineral bath type housing attached to the inside of the hull also. So I can normally run all 3 at once without interference. This one used to work the best, so I hope it is just mud on it. Especially as I could now see it properly, the marble paste worked a treat cleaning up the face - wish I had thought of that yrs ago. Time will tell.

Click to expand...

This may or may not apply, but the "bath" transducers (the ones in a cup filled with fluid) will become erratic and eventually not work at all if the fluid leaks out.

Airmar is now recommending non-toxic antifreeze rather than mineral oil because the oil can sometimes disolve whatever was used to seal the cup to the hull and leak out.

For the original poster: Just curious -- when you say there are two on the boat and neither work, have you tested them one at a time, or both at the same time? Transponders can interfere with each other if both are on at the same time.

@PeterB:
Touch the transducer while it is sending -- almost every transducer I have used will be strong enough to feel it "click" for lack of a better term when it is shooting. No click = no accoustic sending = no response.

I have a difficult time imagining a reason that all three sounders, on different frequencies and locations, would all fail at relatively the same time because of a dirty hull... Have you have added any electronic equipment that would cause electronic interference?

mattkab said:

@PeterB:
Touch the transducer while it is sending -- almost every transducer I have used will be strong enough to feel it "click" for lack of a better term when it is shooting. No click = no accoustic sending = no response.

I have a difficult time imagining a reason that all three sounders, on different frequencies and locations, would all fail at relatively the same time because of a dirty hull... Have you have added any electronic equipment that would cause electronic interference?

Click to expand...

Good thought re the clicking test Matt. I have heard it doing that before, but did not think (from up in the flybridge) to dive down to the ER and listen/feel for the click - will do so next time I'm there.
No issue with other sounders - ? gave wrong impression. The old Seafarer and the newer Lowrance colour GPS/sonar combo still working fine. However, they are both down at main helm, the one now not working (temporarily I hope) is the only one I have up top.

Thanks all. I read the instructions on my transducer, went into the engine room, pulled the pin on the transducer (as if pulling the pin on a granade) and pulled it out. I replaced the transducer with a plug (which was tied onto the transducer line) and the water flow stopped. My fear was that this wouldn't work. Alas, I held a dirty transducer in my hands. I cleaned and brushed it off. I replaced it and the depth sounder still didn't work. I drove to Fisherman's Marine and bought a new fish finder/depth sounder on clearance. I expoxied the new tranducer to the hull and it works like a dream. Problem solved for $288 and may be able to find some fish to boot!

Good solution then Sam. Yes, these modern sonars are so jolly powerful I don't see many occasions when one would want to cut a hole in the perfectly good bottom. You just set them inside and away you go. The main reason I was hoping to resurrect the fly-bridge sonar with its thru-hull, was not because of the thru-hull, but because all the wiring and cabling is laid in all the way from bilge to fly-bridge, and I'm hating the thought of having to rip it all out only to run the new one. Sadly the cables are not the same if I have to go new.