Odd reading on fish finder. Help?

@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

i'd do lake sonoma.  would be a bit further of a drive for you but would definitely be a better test since it would have a thermocline and access to deep water.

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

Agree with Bushy, air bubbles would generally render the reading completely useless (ie 0 depth or a reading of ---).  That generally won't happen in a kayak at kayak speeds, as we're simply too slow to generate the speed necessary to form a bubble.  I have my transducer sitting right on top of my prop on my propel drive - if there were going to be any air bubble or cavitation problems it would show up in my setup, going around 5mph with a prop.  It doesn't.

... For example, line counter says 80 ft, sounder says between 35-40 feet.  ...

Maybe your FF is measuring hexa-deca-liters instead of feet.

... For example, line counter says 80 ft, sounder says between 35-40 feet.  ...

Maybe your FF is measuring hexa-deca-liters instead of feet.

Haha maybe a buddy changed some of your setting just to mess with you... this just gave me a great idea!

Line counters can lie! Braid vrs mono vrs floro. All seem to read differently

Line counters can lie! Braid vrs mono vrs floro. All seem to read differently

The answer is metered braid!

"PowerPro Depth Hunter metered braided fishing line is ideal for jigging and trolling. PowerPro Depth Hunter allows you to target fish at specific depths of the water column and set up trolling spreads with lures at precise distances.
PowerPro Enhanced Body TechnologyTM with multiple-color dying process.
4-Color - Blue / Yellow / Green / Orange.
25ft per color = 100ft / 4-color.
Color repeats every 100 feet.
2'' Black hash or tick marking every 5ft – for precise lure depth placement.
Available sizes: 10lb, 15lb, 20lb, 30lb, 40lb, 50lb, 65lb, 80lb, 100lb & 150lb (150lb available only in 1500yd & 3000yd lengths).
Available lengths: 167yds, 333yds, 500yds, 1500yds, 3000yds
Application: jigging and trolling."

Also, not all line counter reels read in feet. Some in yards, and some in meters. Also, line counter are calibrated to a full spool, so as you let out line and the spool gets thinner, the counter gets progressively less accurate.

Sent from my XT1585 using Tapatalk

Line counters can lie! Braid vrs mono vrs floro. All seem to read differently

The answer is metered braid!

"PowerPro Depth Hunter metered braided fishing line is ideal for jigging and trolling. PowerPro Depth Hunter allows you to target fish at specific depths of the water column and set up trolling spreads with lures at precise distances.
PowerPro Enhanced Body TechnologyTM with multiple-color dying process.
4-Color - Blue / Yellow / Green / Orange.
25ft per color = 100ft / 4-color.
Color repeats every 100 feet.
2'' Black hash or tick marking every 5ft – for precise lure depth placement.
Available sizes: 10lb, 15lb, 20lb, 30lb, 40lb, 50lb, 65lb, 80lb, 100lb & 150lb (150lb available only in 1500yd & 3000yd lengths).
Available lengths: 167yds, 333yds, 500yds, 1500yds, 3000yds
Application: jigging and trolling."

Good stuff. Thanks John!!!

shark

Fishing in a river the other day with lots of changes in depth, I was feeling frustrated trying to spot larger fish because the depth scale on the display kept bouncing from 8-feet to 30-feet and the size of the fish arches kept changing.

Set the depth to 30 feet.  Paddled over a 6-foot deep section.  Had exactly the same multiple bottoms you described.  Set the range (depth) back to "AUTO" and everything returned to normal.

Don't know I that's the problem you're having or if it will help.  Hope so.

Ran across this in a Lowrance article (http://support.lowrance.com/system/selfservice.controller?CONFIGURATION=1001&PARTITION_ID=1&secureFlag=false&CMD=VIEW_ARTICLE&ARTICLE_ID=2967)

"Sensitivity

"To properly adjust the sensitivity while the unit is in the manual mode, first change the range to double its current setting. For example, if the range is 0 - 40 feet, change it to 0 - 80 or 0 - 100 feet. Now increase the sensitivity until a second bottom echo appears at twice the depth of the actual bottom signal. This "second echo" is caused by the echo returning from the bottom reflecting off the surface of the water, making a second trip to the bottom and returning. Since it takes twice as long for this echo to make two trips to the bottom and back, it shows at twice the depth of the actual bottom. Now change the range back to the original scale. You should see more echoes on the screen. If there is too much noise on the screen, back the sensitivity level down a step or two."

Well, I didn't get a chance to review this thread before the weekend, but I did get a chance to play with the settings yesterday.  I was out at Lawson's Landing.  I turned off 'auto sensitivity' and set it to 95, according to the video posted above in this thread.  That seemed to help quite a bit- no more false bottom readings.  Yay!

Now what I noticed is that in shallow water, the depth reading seems to be pretty inaccurate.  I was in about 4.5 feet of water, but the depth reading on the sounder said water depth was 8-9 feet.  I know the 4.5 feet is reasonably accurate, as I gauged depth using my paddle.  The most obvious explanation is my transducer wasn't level, which is what I suspect.  Once I was home and rinsing the boat, I noticed the transducer was angled slightly- this has been an ongoing issue, getting the mount rigid enough.  I think I might have to put a plastic shim between the top of the transducer and the bottom of the hull to keep the transducer from shifting. 

But hey, at least it looks like the false/double bottom issue has been sorted out. 
G

Well, I didn't get a chance to review this thread before the weekend, but I did get a chance to play with the settings yesterday.  I was out at Lawson's Landing.  I turned off 'auto sensitivity' and set it to 95, according to the video posted above in this thread.  That seemed to help quite a bit- no more false bottom readings.  Yay!

Now what I noticed is that in shallow water, the depth reading seems to be pretty inaccurate.  I was in about 4.5 feet of water, but the depth reading on the sounder said water depth was 8-9 feet.  I know the 4.5 feet is reasonably accurate, as I gauged depth using my paddle.  The most obvious explanation is my transducer wasn't level, which is what I suspect.  Once I was home and rinsing the boat, I noticed the transducer was angled slightly- this has been an ongoing issue, getting the mount rigid enough.  I think I might have to put a plastic shim between the top of the transducer and the bottom of the hull to keep the transducer from shifting. 

But hey, at least it looks like the false/double bottom issue has been sorted out. 
G

Are you using auto depth ?

No, not using autodepth. (didn't even know it was an option)  I had set the range to 20 ft.  Seemed like most of the time the depth was accurate, except for when in water less than 5 ft deep. 
G