Explaination for this?

[Cicada]

Some days I get these angled streaks on my screen. There were a lot of them yesterday. Are these agressive fish running up for something? Most fish I show at this depth are acrs. There are no snags, so these are not trees or weeds or anything likie that. Just wondering what theories might be out there.

[sorenson]

They look like gas bubbles, the way they are all ascending as basically the same angle.

S.

[Cicada]

Interesting, but they didn't make it to the surface. It was dead calm and there were no bubbles getting all the way up.

[Dusty]

looks like electrical interference. Is the unit on the dash or the bow? What battery is it hooked up to?

[Hoffer]

Did you have any loons nearby?

when I was in Canada a few weeks ago - I would pass by a few loons and I would show arcs like the biggest one on your screen. But that would have to be a lot of loons!! ....but they did look just like that.

[Tom7227]

I also get them on my HDS 5. Not that many loons on Bald Eagle.

[Cicada]

I think I can eliminate electrical interference. It doesn't happen all the time and I would get into certain areas in the same vicinity and they wuold disappear. For the record, it is mounted near the transom and hooked to the starter battery. Out all day today and didn't see them once.

[Dusty]

sounds like you have that part figured out. maybe to much sensitivity?

[CAMAN]

I'm almost certain it's gas bubbles. They don't have to be very big to create a large mark on a locator.

Have you ever been ice fishing and seen marks on your flasher where the line would be that also goes up when you jig? Bring it up and you will see the size of the bubbles is about the size of a pinhead or smaller.

[Cicada]

I'm liking the gas bubbles theory, but with that many bubbles, I would have thought I'd see them come to the surface. Oh, the other thing I was going to mention. Notice the gps side. You can see the lake chip depths and my trail. The trail follows 22-26 foot actual contour of the lake.

[Rick G]

I would just say it's one of the 520 series flukes. I have a 525 on the front and a 522 on the back of my boat and neither has worked perfect all the time

[TruthWalleyes]

Very slow moving boat with wide angle sonar...

As fish is on outer edge of cone, fish shows up a a deeper return on the graph...As boat moves closer to fish, fish remains at same depth, but appears to be higher in the water column on the graphs - because it is now closer to the transducer...

Similar to how the traditional 'arc' is created by a fish swimming under and through the transducer cone.

Gas bubbles

Had me laughing there.

Ya know how on your flasher in the winter, fish seem to always rise to the bait...Well, most likely they are appearing deeper and are on the outer edge of the cone, as they swim under the hole, they appear to be rising in the water column...When they are really just getting horizontally closer to the transducer.

[TruthWalleyes]

[CaptainMusky]

Notice the gps side. You can see the lake chip depths and my trail. The trail follows 22-26 foot actual contour of the lake.

Map chips are extremely helpful, but in many cases and on some lakes they are not very accurate.

One thing that may have occured is you didnt have a very good "lock" with satellites. Next time you notice something like that view how many satellites you are connected to and possibly add the estimated foot error (I believe that is what it is called on your unit). You will be able to tell when you have a good lock based on this number as you get accustomed to watching it.

This varies daily and especially throughout the year because "visible" satellites change over time.

[Tom7227]

I don't think it is his rig because I get the same thing with my HDS5. It shows up while moving and while anchored. And the odd thing is that I think it always shows up from low left to higher right as shown on the first post.

Keep coming up with ideas.

[sunniewally]

I get those alot too, but I have no clue what it could be, I have a humming bird.

[Stick in Mud]

Yup, I see it all the time, too. I've ignored it until now.

[bobbymalone]

I know what you are saying, but I don't buy it.

some of those things go from 15 to 10 feet. or 30 to 20 feet. The cone angle isn't wide enough to explain that.

Don't make me break out the geometry.

actually i think it's trigonometry. been a long time.

[delcecchi]

Cosine 20 degrees is .93 so only a few feet difference between edge and center of cone.

[bobbymalone]

Cosine 20 degrees is .93 so only a few feet difference between edge and center of cone.

at 10 foot, that's less than a foot. I looked up that lowrance unit and I think the wide angle cone is 35 degrees, so 17.5 either direction.

thanks for the trig, del )

[bobbymalone]

I also think the "way it is" is more like this. Drawing is cruddy, but you get the idea. Feel free correct me if I'm wrong.

[delcecchi]

Good point about the blind spots. I forget about those. But while they are important while fishing they don't explain those lines.

[bobbymalone]

no they don't...

[Cicada]

Wow, I thought it was kind of a simple question... I think my satellite lock was fine. My point was that the map chip shows the break running east to west and it actually is a bar that runs along my trails. Besides, I think the estimated foot error function is to allow for things like your transducer being mounted a foot below the waterline, not for correcting 10 or more feet differences between your actual depth and the depth the map shows. I have yet to see a map that shows this point correctly.

[TruthWalleyes]

Angled streaks = boat traveling over fish (Fish moving from outside of cone to center of cone) This is normal. Not GPS Related.