Raymarine depth randomly cycles down to 0 and back up again

[benzy]

I installed a new Raymarine instrument pack. It includes:
- ITC-5
- i70s screen
- P19 depth transducer

The depth works mostly fine, however, every now and then, and funny thing happens where the depth will suddenly cycle down to 0.0m and then cycle back up to correct reading. It might do this 3 times in a row before settling down to the correct reading again. The cycling takes maybe 5 seconds to go down to 0 and back up again.

Has anyone seen this before and know how to troubleshoot it?

Thanks

[paulajayne]

Is this when underway?

[Sojourner]

I think all depth sounders (our raymarine included) enjoy randomly freaking you out by suddenly shoaling up to juuust less than your draft, then going SIKE jk it's really still 1000 meters down here Ours doesn't 'cycle' tho, just occasionally in water too deep to measure. When it does it in shallower water it's probably a tarp or whale or thermocline. That's what I tell myself anyway....

[benzy]

I think it's only when underway...I might recall having seen it do it at anchor the other day.

Sojourner, I also get the issue you describe when in deep water, but that is a different issue (based on much research!). This cycling issue is happening in water anywhere form 5 to 15 meters.

The only thing I have come across relating to the cycling is to do with static buildup. But no idea why or how to test that (apart from "rubbing a cotton shirt on the screen, which didn't work)

[transmitterdan]

If any air bubbles pass under the transducer then this will be the result. Also, turbulent water can also cause this effect. Air bubbles under the transducer block the return echo causing it to report depth zero. Turbulent water can cause echoes which will often cause the transducer to report depth of the turbulence rather than the true bottom. So the transducer has to be placed where it will not be exposed to bubbles or turbulence when underway. In waters with high tidal currents the turbulence can cause shallow readings.

Some transducers have a dual frequency feature that can combat the problem. Be sure you have not turned this feature off. And you might experiment with using different fixed frequencies to see if one is better than another.

[a64pilot]

Usually, almost always 50 Hz works better in real deep water, mine will still work in 2500’, I’ll know this weekend how deep, cause I’ll be in 12,000’

200 Hz, the higher freq. gives much better resolution for shallower water and if you have a plotter, better resolution for determining bottom type.

However what you describe, I also have in my boat, when the weather really kicks up like as in a squall, my depth meter is unusable, it merely displays “Last” and is due to aeration.
I installed a second transducer to connect to my plotter so that I would have a usable depth in a squall.
Mine is installed too close to the bow, I assume that was done in an attempt to detect shallows before you run aground, but suffers from aeration.

[tml]

Our Raymarine Depth will quit in shallow water and display boat speed and some times shift to fathoms. Happens every couple of weeks of course when you are trying to navigate between coral heads! It won't reset from the display but will if you turn all the Raymarine instruments plus the auto pilot off and back on.
It is mounted far forward and as a64pilot suggests may suffer from aeration.
The forward mounting position has proved useful when trying to sniff out where the better water is in the ICW!
Tom

[Caleb C]

Originally Posted by transmitterdan

If any air bubbles pass under the transducer then this will be the result. Also, turbulent water can also cause this effect. Air bubbles under the transducer block the return echo causing it to report depth zero. Turbulent water can cause echoes which will often cause the transducer to report depth of the turbulence rather than the true bottom. So the transducer has to be placed where it will not be exposed to bubbles or turbulence when underway. In waters with high tidal currents the turbulence can cause shallow readings.

Some transducers have a dual frequency feature that can combat the problem. Be sure you have not turned this feature off. And you might experiment with using different fixed frequencies to see if one is better than another.

Interesting explanation of depth reading anomalies. I've been curious why we get random inaccurate depth readings too. I've leaned toward nosy submarines though. LOL

[saillr]

My transducer is mounted about 1/3 distance from the bow on the flatest portion of the hull. It is near the leading edge of the keel but angled slightly away or say about 5 degrees from flat. I have always had the same problem with raymarine especially when over-depth and under way. The sounder is single freq. and rated to 600' and works reasonably well at that depth but that is its limit. After that it is searching for the bottom. It could be aeration or perhaps it is picking up a slight return from the bottom of the keel causing it to go into a tailspin.
I like the whale idea better tho' or maybe a mermaid.

[Gradient]

We used to call our Raymarine Depth Transducer the "Random Number Generator". Had loads of dramas, especially in shallow water. Other things used to happen as well such as the wind transducer re-setting the calibration. After many visits by marine electricians and Raymarine themselves we changed the 5 way wiring blocks for T's so that every instrument spur is off a T and viola, everything stabilised and the issue was solved. Overall we've had a terrible run with Raymarine, so for we're on our 2nd E120 plotter (the replacement was sent back within a week due to faulty touchscreen), 2nd AIS module, 3rd wind and 3rd depth transducers, all on warranty. I had a Raymarine engineer openly tell me their new range is crap compared to the older generation equipment!

[benzy]

Thanks for all the suggestions. I’ve read a lot about turbulence and bubbles, etc, but I don’t think it’s that. In my experience (like when reversing hard and the prop wash ends up under the sensor) then the numbers go all random.

However, this is different, as I described, the numbers count down and then sit on zero for a bit before counting back up. And it might do this three time in quick succession before stabilising.

Gradient, interesting about the 5 way connector vs the T piece. I’ll try and give that a go.

Also in terms of Raymarine support in Australia, what’s the best way to contact them? I’ve emailed and they take forever to respond. Are they any good over the phone?

[transmitterdan]

Benzy,

In the count down situation it sounds like a loose connection somewhere. This is what happens when the signal is lost and then restored. It counts down and then counts back up. The rate at which it counts is related to the filtering setting.

I would look for a loose or corroded connector between the display and the transducer. Depth transducer cables should not be cut and spliced. I see people do this but it’s a really bad idea.

[benzy]

Yep could be a loose connection. I will check next time I’m onboard.

Having said that they whole system in on SeaTalkNG network, and I didn’t mess with the transducer cable - just plugged it into the ITC5 as is. And it’s all very new! So would be surprised if there was a dodgy connection.

[Alan Mighty]

You've likely read the story about the boatyard in Seattle WA reported in the Dec 2018-Jan 2019 issue of Professional Boatbuilder.

Story included a tale about a depth sounder on a Nordhavn displaying a horizontal line at a depth of 10 ft (3 m).

The yard replaced the transducer. Problem not solved.

So the yard pulled new cable (photo of a yard worker hauling the new cable to the transducer is the cover pic of that issue of PBB). Problem not solved.

Furuno tech attended. Problem not solved.

Seems everyone just shook their heads and declared it was likely a problem of the exact location/orientation of the transducer somehow making it liable to pick up sonar signals bouncing from or resonating against the keel. Owner told to live with it.

[transmitterdan]

Originally Posted by benzy

Yep could be a loose connection. I will check next time I’m onboard.

Having said that they whole system in on SeaTalkNG network, and I didn’t mess with the transducer cable - just plugged it into the ITC5 as is. And it’s all very new! So would be surprised if there was a dodgy connection.

Be sure the terminators are good and in the right place on the network. These terminators are responsible for flaky results sometimes. Sometimes the network will work without the terminators and sometimes not. So it may not be the new connection that's the problem. It may be a pre-existing one.