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Topic: Odd reading on fish finder. Help?  (Read 2261 times)

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gweaver

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Added a Hook 7 to my Viking Profish 440.  The yak has a recess in the bottom of the hull to mount the transducer.  This isn't mine,
 but picture for reference.


Anyway, both times I've taken it out, I've noticed that the depth reading on the Hook is about half of what the line counter says I'm in.  For example, line counter says 80 ft, sounder says between 35-40 feet.  The other odd thing is I'm getting what I can best describe as a 'double bottom'.  One bottom drawn at 35-40 feet, the other around 80 feet. 

The transducer is mounted level, set to within 3/8-1/2" of the bottom of the kayak.  I don't think there's an air bubble or anything that would give a false reading like that.  I called the Lowrance rep, he didn't have any answers.

At this point, I'm wondering about using expansion foam to try to fill in the space 'above' the transducer in the hopes of eliminating any possible bubbles, but I'm not sure if that's a good idea or not.

If anyone has any ideas, I'd love to hear them.

I'll try to take a picture of the existing mount when I get home, so you can see exactly what I'm dealing with.
Thanks,
Greg


CptSloppywood

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Check your sensitivity settings. It sounds like your sensitivity is up to high.


CptSloppywood

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You must be seeing the thermocline. You might just need to adjust the sensitivity by turning it down until you don't see it .


E Kayaker

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What is the digital depth reading say, 40 or 80 feet? If your in 40 feet of water and you depth finder is set to show 100 feet you will get a double bottom. One at 40 and one at 80.
http://www.norcalkayakanglers.com/index.php?topic=42846.msg470404#msg470404

The charm of fishing is that it is the pursuit of what is elusive but attainable, a perpetual series of occasions for hope.  ~John Buchan


gweaver

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The depth reading on the sounder read 40-ish feet, the line counter on the read said my depth was around 80 feet.

A couple of pictures of my install:
Transducer tucked up in the recess in the hull bottom.



It sticks down just a hair- maybe 1/4" below the bottom, but still protected by the keel ridge.  Thinking about trying to fill the open space in the recess with foam or something, to try to prevent air bubbles from causing issues.



Not sure how to adjust sensitivity, but I can probably figure it out.  One thing worth noting- I had this unit installed in my boat this summer- absolutely no issues with false bottom readings or anything else.  Fresh water (Lake Sonoma), depths from 8ft down to 180 or more.  Just a nice clear image.  Trying to figure out why installing it in a kayak in salt water would cause issues.

Only one other thing, which I'm not convinced is the problem- I'm using one of those Humminbird battery kits- a little lead-acid battery, I think 7.4 Amp-hours.  I had the voltage displaying on the screen, the entire time it was 12.7V or higher.  Made sure battery was fully charged.  My buddy thinks the Hook 7 might be pulling more power than the battery can handle, I don't think that's the case, and I don't think that's why the funny readings.

G


NoSoupForU

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This video nails the sensitivity settings, but at about the 2:05 mark he talks about noise reduction.   When they show the menu at that 2:05 mark you will see Fishing Mode.  See what your's us set at.  Make sure it is not set to "Deep Water".  I've had that give false readings before.  Mine is usually set for "General Use".


« Last Edit: September 06, 2017, 09:21:37 PM by NoSoupForU »


NoSoupForU

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Only one other thing, which I'm not convinced is the problem- I'm using one of those Humminbird battery kits- a little lead-acid battery, I think 7.4 Amp-hours.  I had the voltage displaying on the screen, the entire time it was 12.7V or higher.  Made sure battery was fully charged.  My buddy thinks the Hook 7 might be pulling more power than the battery can handle, I don't think that's the case, and I don't think that's why the funny readings.

G
It's not your battery.


Life_is_Yak

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Only one other thing, which I'm not convinced is the problem- I'm using one of those Humminbird battery kits- a little lead-acid battery, I think 7.4 Amp-hours.  I had the voltage displaying on the screen, the entire time it was 12.7V or higher.  Made sure battery was fully charged.  My buddy thinks the Hook 7 might be pulling more power than the battery can handle, I don't think that's the case, and I don't think that's why the funny readings.

G
I'm not sure if this is accurate but your transducer looks a lot like my hummingbird compact transducer.  If your using a hummingbird transducer with a lowrance unit that might cause problems.

another thought put dielectric grease on all connections.  I had an issue once after rolling my kayak in the surf.  The sonar unit was showing weird lines and stuff, sounds similar to your case.  I thought I damaged my unit.  After greasing all the connection everything worked normal again.  Now I grease all the time.

not that it matter but the unit I had issues with was a Hummingbird 798 si HD


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The depth reading on the sounder read 40-ish feet, the line counter on the read said my depth was around 80 feet.

A couple of pictures of my install:
Transducer tucked up in the recess in the hull bottom.



It sticks down just a hair- maybe 1/4" below the bottom, but still protected by the keel ridge.  Thinking about trying to fill the open space in the recess with foam or something, to try to prevent air bubbles from causing issues.



Not sure how to adjust sensitivity, but I can probably figure it out.  One thing worth noting- I had this unit installed in my boat this summer- absolutely no issues with false bottom readings or anything else.  Fresh water (Lake Sonoma), depths from 8ft down to 180 or more.  Just a nice clear image.  Trying to figure out why installing it in a kayak in salt water would cause issues.

Only one other thing, which I'm not convinced is the problem- I'm using one of those Humminbird battery kits- a little lead-acid battery, I think 7.4 Amp-hours.  I had the voltage displaying on the screen, the entire time it was 12.7V or higher.  Made sure battery was fully charged.  My buddy thinks the Hook 7 might be pulling more power than the battery can handle, I don't think that's the case, and I don't think that's why the funny readings.

G
your transducer install looks fine. Unless the transducer itself is faulty I think its a head unit settings problem.  take your manual on the water with you and dial it in, or take a smartphone out and watch a bunch of youtube videos on how to adjust settings while you're out there.  I think it will work fine, ultimately.


E Kayaker

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Just paddle over to someone else with a FF and ask them what depth they are reading. I wouldn't assume it's broken just because of the line Counter. Set the depth display to auto or a number closer to the depth you're in to avoid the double bottom on the display.
http://www.norcalkayakanglers.com/index.php?topic=42846.msg470404#msg470404

The charm of fishing is that it is the pursuit of what is elusive but attainable, a perpetual series of occasions for hope.  ~John Buchan


gweaver

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Looks like it might be a week or more before I can get it out in the water, but I'll try to adjust the sensitivity down a step or two and report back when time permits.
Thanks for the suggestions, folks!
G


CptSloppywood

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No soups video is great. Follow that and read and reread your manual.


CptSloppywood

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I don't think you should fill in the cavity behind your transducer. I have a similar gap in my tackle pod and I get very accurate readings when my settings are appropriate to conditions.


gweaver

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@CptSloppywood-
Noted.  Filling the void was more of a 'last ditch' option if my issue was related to air bubbles due to the transducer install.   I'll try to adjust sensitivity first.  Hopefully that takes care of the issue.
Need to figure out how I can get a couple of hours to throw the boat in the water and do some testing.  Maybe the marina in Petaluma?  Although the river is pretty shallow, it'd probably be better to test in deeper water. 
G


Bushy

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If your transducer is in the water.....It's not air bubbles.

I'd say adjust settings as discussed above.  Basically you will be tuning in your FF.

And, you can call the manufacturer they can tell you what's what.

Bushy

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