Help! Fish finder interpretation

[filletedalive]

Hoping some of you would be willing to shed some light on what I am seeing on my garmin striker 4 fish finder.





This is with the 200hz signal and the screen scroll set to auto. 

I get these diagonal lines or slashes. I have yet to see a defined “arch” on the screen. The bottom readings feel like they are accurate only cause I can see bowls, humps, sunken logs, and I think bushes. But I am not sure what to make of these diagonal lines.
I would appreciate any feedback. This is my first fish finder mounted on a float tube.

[a_bow_nut]

It looks like air bubbles coming up from the bottom.

[TubeDude]

I was probably one of the first float tubers to ever use a sonar on my tube.  Way back in the early 80's I rigged an old flasher unit with dual 6 volt lantern batteries in series and just balanced the display on the front of my tube.  Since then I have bought and used maybe 20 different sonar setups...trying to find the best for tubing.  A lot of the low end early models just showed little fishy symbols...for everything from tree branches to gas bubbles...to fish.  Our more sophisticated modern systems are more definitive...especially the color models.

I also have a Garmin Stryker on my tube...a model 7.  And I can assure you that not seeing inverted Vs on your screen is common with slow moving or stationary float tubes.  The V marks show up mostly when you are moving over the water and the sonar signal moves along a fish...with an air bladder...to produce the characteristic mark.  If I am moving with any speed using my electric motor the marks I see are different than when slowly kicking or fishing stationary.

As with all systems, you will learn to translate what you are seeing on your screen into useable info for making presentations and catching more fish.  The frustrating part is seeing fish and not catching them.  That's fishing.

[JazzyM]

Hey Pat. I was just wondering. Dangerously thinking. What haven’t you tried to mount on a tube?

[TubeDude]

Hey Pat. I was just wondering. Dangerously thinking. What haven’t you tried to mount on a tube? 

Been tough to mount downriggers.  Every time I try to screw or bolt down the base plate my tube goes flat.

Otherwise, there ain't much I haven't tried or don't currently use.  Just like a mini bass boat...only everything within easy reach.  Oh yeah, I have a tough time getting up on plane with my 40# thrust MinnKota.
 

Here are some pics of current and former mods.

[BearLakeFishGuy]

Those diagonal lines are mostly caused by the transducer not being perpendicular to the bottom. (There is a slight chance it could be fish ascending/descending in the water column quickly though). I've seen this many times on some hyrdoacoustic returns from survey-grade sonar (price about $50K) and once the transducer is adjusted, it will turn the fish into purdy little arches. Also, make sure the transducer is not only orientated to 90 degrees to the bottom/fish, but also orientated towards the direction you are traveling. If you have anything but an ice fishing style transducer (think: upside down ice cream cone in shape), this could also cause the arches to turn into "slash marks".

[filletedalive]

Those diagonal lines are mostly caused by the transducer not being perpendicular to the bottom.  (There is a slight chance it could be fish ascending/descending in the water column quickly though).  I've seen this many times on some hyrdoacoustic returns from survey-grade sonar (price about $50K) and once the transducer is adjusted, it will turn the fish into purdy little arches.  Also, make sure the transducer is not only orientated to 90 degrees to the bottom/fish, but also orientated towards the direction you are traveling.  If you have anything but an ice fishing style transducer (think: upside down ice cream cone in shape), this could also cause the arches to turn into "slash marks".

This is the transducer it came with. I know it rides 6 inches under the water and I can click adjust it up or down. I think it’s close but for all I know. I could have it pointed the wrong way. I’ve only used vexilar transducers through an ice hole lol 

[doitall5000]

Those diagonal lines are mostly caused by the transducer not being perpendicular to the bottom.  (There is a slight chance it could be fish ascending/descending in the water column quickly though).  I've seen this many times on some hyrdoacoustic returns from survey-grade sonar (price about $50K) and once the transducer is adjusted, it will turn the fish into purdy little arches.  Also, make sure the transducer is not only orientated to 90 degrees to the bottom/fish, but also orientated towards the direction you are traveling.  If you have anything but an ice fishing style transducer (think: upside down ice cream cone in shape), this could also cause the arches to turn into "slash marks".

I agree that those are fish, but you are not moving quick enough to create the arc. The arc is caused when the fish is passing under the boat. I have seen kokanees fly under the boat making lines going straight up and also straight down when the fish is diving to avoid the boat.
If you change the settings to show the fish image. You will better under stand your picture the way you are using it. Try that and see.

[filletedalive]

Ha ha ha I’m pretty sure I had it backwards. Shame I didn’t catch any fish by their tails, would have made more sense. I flipped the transducer 180 degrees and will get it back out this weekend for another test run.

[JazzyM]

Hey Pat. I was just wondering. Dangerously thinking. What haven’t you tried to mount on a tube? 

Been tough to mount downriggers.  Every time I try to screw or bolt down the base plate my tube goes flat.

Otherwise, there ain't much I haven't tried or don't currently use.  Just like a mini bass boat...only everything within easy reach.  Oh yeah, I have a tough time getting up on plane with my 40# thrust MinnKota.
 

Here are some pics of current and former mods.

Yep yep. That’s one tricked out tube. Bass pro tube

---

Hey Pat. I was just wondering. Dangerously thinking. What haven’t you tried to mount on a tube? 

Been tough to mount downriggers.  Every time I try to screw or bolt down the base plate my tube goes flat.

Otherwise, there ain't much I haven't tried or don't currently use.  Just like a mini bass boat...only everything within easy reach.  Oh yeah, I have a tough time getting up on plane with my 40# thrust MinnKota.
 

Here are some pics of current and former mods.

Yep yep. That’s one tricked out tube. Bass pro tube

[Joe_Dizzy]

Hoping some of you would be willing to shed some light on what I am seeing on my garmin striker 4 fish finder.





This is with the 200hz signal and the screen scroll set to auto. 

I get these diagonal lines or slashes. I have yet to see a defined “arch” on the screen. The bottom readings feel like they are accurate only cause I can see bowls, humps, sunken logs, and I think bushes. But I am not sure what to make of these diagonal lines.
I would appreciate any feedback. This is my first fish finder mounted on a float tube.

Those diagonal lines are fish rising up off the bottom. Likely snatching chironomid pupa that are starting their ascent to the surface. 

I have a Garmin on my tube (kicking/rowing) and see these all the time when targeting trout. It's exactly the kind of activity I'm looking for when hanging a chironomid imitation off of an indicator.

Suspended fish (on a slow-moving watercraft) show as horizontal lines across the screen.