Stacked marks, what is it?

[kid coulson]

Alright, what causes this/what is it? Im sure its not a school of kings playing leap frog!

[BenLubbs]

I have always wondered the same thing on my graph.

[CITM]

I'd guess air bubbles over the transducer, probably due to waves.

[coralee]

I thought that was an echo bouncing back and forth but not sure about that.

[Richard]

I understand it to be air bubbles as well.

[sherman51]

the only fish I've seen stack is crappie but they didn't look like that line of marks. they were stacked but was more offset and not in a straight line.

sherman

[LongLine]

Possibly a thermal plume. i.e. vertical temp gradient with debris caught in it.

[Paulywood]

I normally see that on my boat when the back end shifts around due to wind or change in direction so I would guess some kind of turbulence.

[Sea-Mac]

I always assumed that to be a school of fish and the reason they stack up like that is because the tranducer is picking up multiple fish @ the same depths within the "signal cone".I know when I start marking that it usually isnt long til fish on. I would like to know the real proven reason for this also, good question.

[SeaCatMich]

Never seen anything like that on any of my graphs over the years. What brand/model is the graph?

[fishy1]

If you are fishing near another boat at times you may see interferences from the other boats similar to what you are showing due to frequency interference from thier graph or any other equipment that is sending a pulse thru a transducer.

[jimbobber]

ive been told its sea fleas we always start seeing lots of that when they are thick.

[kid coulson]

Thanks for the replies guys.

Graph info: Hummingbird 798. I have the sensitivity and most of the settings turned way up(most on max) when out on the big lake. Helps me to see the "arches". Freq is 200/83 KHZ(when in dual beam mode). Its mounted on the back of my 16.5 aluminum boat.

I don't get these marks like that all the time. Every once in a while, and only on the big lake as I can recall. When I'm on MAC or muskie fishing a smaller inland lake my settings are TOTALLY different and I don't recall seeing this phenomenon.

I kinda thought it might be a rigger cable as the front edge of the marks are so straight all the way down,.. maybe on a tight turn or something??

But,..I never mark the cable on the graph. I do mark the ball if going slow enough.

I have a couple e-mails out to Humminbird "pro staffers" but have not heard a thing back yet.

[joelsanders]

could it be a bait kill ,where they spiral slow up to the surface.?

[SUPERTRAMP]

Its usually air bubbles, it can also occur when u r in close proximity to another boat that has their gain turned way up. Check and see if the stacks occurred when u were speeding up or going with the waves and get a big push.

[Creekerman]

I've had the same show up where I've marked it before and passed over the same area more than once...multiple times. I wonder if it is underwater structure...maybe even shipwreck materials? I've had it show up on flat water days too.

[Patio]

Maybe Hummingbird might have an explanation.

[Rascal Trophy Fishing]

I also suspect air bubbles, where the transducer in a wave is just too close to the motor. On a 16' boat, this may be the case, as you have a narrow 4'-5' beam. I would also suggest that you try the separate single frequency, and use about a 3/4 gain setting, no need for the maximum imho, unless you are over 250' fow.

[Yankee Troller]

I've seen that on Lowrance, Furuno, and even now on my Humminbirds. I'm dying to know myself. A friend of mine has sent this image to the engineers at HB, so i hope to have an answer soon.

[CAC]

My lowrance does this too on my 16.5 foot Lund. I will reduce my gain to see if that helps. Thanks for the great topic

[Sea-Mac]

I get it on my Lowrance and cant recall ever seeing it in under 100 fow. I sent the ? out to Lowrance product support today also.

[Sea-Mac]

Lowrance product support says they would say it looks like interference from other sonar sources.

[2UNREEL]

Could be an echo from a flasher off a rigger or a diver and thats how the processor interperates it.....just a guess

[joelsanders]

It's the crackin!!

[hear fishy fishy]

I have also seen this on my Garmin many times and would like to know what it is.