Humminbird 998c SI false shallow water readings????

[96720]

Trying to map an estuary but when ever I get into waters that are less than 2.5' and hard bottomed my unit displays and plot track data record deeper readings than it actually is. The chart display shows the actual depth. Is there any way to resolve this issue?

 

[John_S]

Re: Humminbird 998c SI false shallow water readings????

Try this forum: http://forums.sideimagingsoft.com/index.php?action=forum

Some HB people monitor and there are allot of people that are using the data for mapping and playback.

 

[96720]

Re: Humminbird 998c SI false shallow water readings????

Try this forum: http://forums.sideimagingsoft.com/index.php?action=forum

Some HB people monitor and there are allot of people that are using the data for mapping and playback.

Thanks. I've posted there without replies. Need to broaden my search to find answers........HB support isn't very supportive on this matter. Thanks again.

 

[John_S]

Re: Humminbird 998c SI false shallow water readings????

I assume you have the latest S/W. If the display is fine, but data is not, sounds like you have to wait for a S/W release.

 

[Boatist]

Re: Humminbird 998c SI false shallow water readings????

Some times units will not allow a reading from such a short time.
When the unit sends out the ping the reciever is turned off. Then the reciever is turned back on to wait for the return echo.
In 2.5 feet this is a very short time for the reciever to come back on. The ping will echo off the bottom then back to the boat then echo off the surface back to the bottom and back to the reciever again. Also since the transducer is on the bottom of the hull the actual distance is even less that 2.5 feet.

I think the unit can probable not react that quickly.
Understand the same crystal that sent out the ping has to settle down from the ping before in can see a echo.

I do not know your unit but if you wnat to try some things I would first lower the sensitivy. Second I would send out a shorter ping but before you change the ping width note what it is set to first so you can set back to normal

 

[Fireman431]

Re: Humminbird 998c SI false shallow water readings????

Also try setting the time between pulses to a longer interval, say...2-3 seconds.

 

[96720]

Re: Humminbird 998c SI false shallow water readings????

I assume you have the latest S/W. If the display is fine, but data is not, sounds like you have to wait for a S/W release.

Actually, the incorrect digital numerical display is whats being recorded to the plot track log. But, the chart display is showing the correct bottom depth height and contour. Can't understand why both diplays aren't the same?

Some times units will not allow a reading from such a short time.
When the unit sends out the ping the reciever is turned off. Then the reciever is turned back on to wait for the return echo.
In 2.5 feet this is a very short time for the reciever to come back on. The ping will echo off the bottom then back to the boat then echo off the surface back to the bottom and back to the reciever again. Also since the transducer is on the bottom of the hull the actual distance is even less that 2.5 feet.

I think the unit can probable not react that quickly.
Understand the same crystal that sent out the ping has to settle down from the ping before in can see a echo.

I do not know your unit but if you wnat to try some things I would first lower the sensitivy. Second I would send out a shorter ping but before you change the ping width note what it is set to first so you can set back to normal

Thanks, I'll have to check and see if ping width can be set to a shorter width.

Also try setting the time between pulses to a longer interval, say...2-3 seconds.

Is ping width and interval the same? I know I can adjust the ping interval which is currently set at 1 second. I think your suggestion of 2-3 seconds is a good one. Thanks.

 

[j_martin]

Re: Humminbird 998c SI false shallow water readings????

Ping width would matter. It needs to be as short as possible. Ping interval doesn't matter unless you're waiting a long time for the return (very deep water)

If the graphics display correctly, and the data port doesn't, it's a software, or setup problem. Maybe the bottom is mud over rock, and the data is showing the rock, for instance.

Display shows all echos. Stands to reason that a mapping output should show the strongest echo. The first echo might be fish.

just my 02
John

 

[John_S]

Re: Humminbird 998c SI false shallow water readings????

Actually, the incorrect digital numerical display is whats being recorded to the plot track log. But, the chart display is showing the correct bottom depth height and contour. Can't understand why both diplays aren't the same?

Well, I misunderstood your issue. I did go to that forum and looked for your post to see if it had more info, but wasn't able to find it.

On your 2D screen, are you displaying multiple bottoms and it is locked on one of the multiples, caused from reflection back at the surface?

Still, check what version of S/W is loaded and report it back.

If you are covering allot of shallow water at one time, try setting the max depth to a setting between actual and what the false reading are giving you. Of course, once you get out of the shallow water, you will have to adjust that.

I am not sure if you have settings for ping width or interval. Probably not by those names if it does have them. I have my boat in the garage getting it ready. If I get a chance, will go through settings to see if there are ones that might be that.

 

[96720]

Re: Humminbird 998c SI false shallow water readings????

Ping width would matter. It needs to be as short as possible. Ping interval doesn't matter unless you're waiting a long time for the return (very deep water)

If the graphics display correctly, and the data port doesn't, it's a software, or setup problem. Maybe the bottom is mud over rock, and the data is showing the rock, for instance.

Display shows all echos. Stands to reason that a mapping output should show the strongest echo. The first echo might be fish.

just my 02
John

Checked the unit and there aren't and adjustments for ping width only ping interval (1-10 pings per second or auto). The recordings in shallow soft bottomed areas seem to both diplay and record data accurately. It's only when I'm in shallow hard bottomed areas that my recordings become inaccuate.

Well, I misunderstood your issue. I did go to that forum and looked for your post to see if it had more info, but wasn't able to find it.

On your 2D screen, are you displaying multiple bottoms and it is locked on one of the multiples, caused from reflection back at the surface?

Still, check what version of S/W is loaded and report it back.

If you are covering allot of shallow water at one time, try setting the max depth to a setting between actual and what the false reading are giving you. Of course, once you get out of the shallow water, you will have to adjust that.

I am not sure if you have settings for ping width or interval. Probably not by those names if it does have them. I have my boat in the garage getting it ready. If I get a chance, will go through settings to see if there are ones that might be that.

When I'm recording I'm usually on the Down Imaging/Side Imaging Combo View. I haven't taken notice if either was "locked" into while recording.

The S/W version is the factory installed v.4.88. I was leary in updating to v.4970 when others experienced "locking up" of the unit and other complications.

Yes, I am covering a lot of shallow water at one time. Your suggestion in setting the max depth to something with in my shallow range is a good one, I will give it a try. Do you think switching from shallow saltwater to fresh water type will help also?

Checked the unit's options again and there isn't any adjustment for ping width only ping interval.

 

[Boatist]

Re: Humminbird 998c SI false shallow water readings????

Ping width or pluse width is not adjustable on many units.
Lowrance has it on their HDS units but the lower end units do not have it. I do not know what humming bird has.

 

[John_S]

Re: Humminbird 998c SI false shallow water readings????

The S/W version is the factory installed v.4.88. I was leary in updating to v.4970 when others experienced "locking up" of the unit and other complications.

Didn't get to my menus last night, but looks like you went through them all. The S/W is at 5.4 now. I recommend updating. If you have another unit and communicate via interlink, they both will need updating. Follow the instructions and you should be fine. I have probably updated my 798 3-4 times, and the 797 before that, a couple of times.

-Plug into good power source, power on.
-Reset to default parameters
-Insert SD card with new S/W.
-Answer prompts.
-S/W Loads.
-When complete, power down.
-Power up, and change parameters back.

 

[96720]

Re: Humminbird 998c SI false shallow water readings????

Didn't get to my menus last night, but looks like you went through them all. The S/W is at 5.4 now. I recommend updating. If you have another unit and communicate via interlink, they both will need updating. Follow the instructions and you should be fine. I have probably updated my 798 3-4 times, and the 797 before that, a couple of times.

-Plug into good power source, power on.
-Reset to default parameters
-Insert SD card with new S/W.
-Answer prompts.
-S/W Loads.
-When complete, power down.
-Power up, and change parameters back.

Scheduled to do some mapping this AM. Will try some shallow water recording with some of the suggestions mentioned earlier. Time allowing I'll try the S/W update this afternoon. Thanks again.

 

[96720]

Re: Humminbird 998c SI false shallow water readings????

Originally Posted by imported_John_S
Didn't get to my menus last night, but looks like you went through them all. The S/W is at 5.4 now. I recommend updating. If you have another unit and communicate via interlink, they both will need updating. Follow the instructions and you should be fine. I have probably updated my 798 3-4 times, and the 797 before that, a couple of times.

-Plug into good power source, power on.
-Reset to default parameters
-Insert SD card with new S/W.
-Answer prompts.
-S/W Loads.
-When complete, power down.
-Power up, and change parameters back.

Scheduled to do some mapping this AM. Will try some shallow water recording with some of the suggestions mentioned earlier. Time allowing I'll try the S/W update this afternoon. Thanks again.

Tried the "fixes" earlier........didn't work, the readings in the digital numeric read out and chart were different. Did the S/W update now both readings are the same. I'll check later in HBPC to see if the track plot data recorded to the SD card is showing the correct readings. Thanks again, John_S. Still can't believe the updated S/W would have made the difference.

 

[96720]

Re: Humminbird 998c SI false shallow water readings????

Well, just checked my track plot data that was recorded after the S/W update. There wasn't any depth information on the first 251 tracks then something kicked in and got depth data for the last 221 tracks for that set. The depths that were recorded were correct. I'll try again tomorrow morning and see how it goes.

 

[96720]

It happened again....

It happened again....

It happened again, no depth record for the first 224 entries in the track plot log data. There wasn't any depth and the GPS coordinates were way off. Then like yesterday, the unit begins recording correct track plot data............ software issue again?? Think I'll reload the software update and see what happens. Any ideas or suggestions?

 

[John_S]

Re: It happened again....

Re: It happened again....

It happened again, no depth record for the first 224 entries in the track plot log data. There wasn't any depth and the GPS coordinates were way off. Then like yesterday, the unit begins recording correct track plot data............ software issue again?? Think I'll reload the software update and see what happens. Any ideas or suggestions?

No, I wouldn't reload tha same S/W. Very unlikely there was a bad load. I would save the data and write a detailed "bug" report and send to HB. Also post info on that other site.

 

[96720]

Re: It happened again....

Re: It happened again....

No, I wouldn't reload tha same S/W. Very unlikely there was a bad load. I would save the data and write a detailed "bug" report and send to HB. Also post info on that other site.

I?ll hold off on reloading the S/W until I receive more advice on that issue. I did submit a report to HB and also posted details on the other site.

Here?s how it went today, I only got 17 tracks of no depth data. The location coordinates were accurate then, as before, the data logs a random location (on the 16th entry) and it begins recording the correct depth. An interesting note is that the "random location" given this time was only 380 feet away from the one I had on day one. Any ideas??