Precision Trolling Depths

[hermit]

I just got a Hero4 Silver GoPro for Xmas and will be taking it to Yellowstone in late June to try out and I'm not sure whether the volcanic activity out there is any more dangerous than trusting my downrigger wire  for underwater shots....maybe when it isn't so new   Tyee I think you may be more of a risk taker at this point than me 

 

Les just a word of warning, and I don't know how GoPros do in these conditions but I ruined a good digital camera by getting close to volcanic activity several years ago- the gasses they give off are can be very corrosive to electronics.  My guess is the GP would fare better but perhaps when filming near volcanic activity use the underwater case to keep those gasses out.   Or at least it's something to look into.  Also enjoy the trip!

[skipper19]

Almost always a flasher and fly

That's the best setup I've had for a "tailgun" second shot, only I use a 100 foot copper now, instead of the dipsey. I attach the copper backing in a Scotty cable release 15 to 20 feet above the ball. The lookers often at the ball will drop back as noted, and see the second offer as a feeding salmon (large flasher and fly) and might see the fly as a wounded miss. Also I believe fish that pod or school are greatly affected by the herd mentality. In essence if one is feeding, others will feed triggered by actions of the others as it developes into a frenzy type of feed. Competition on a single bait can trigger some of the most vicious strikes in most fish, hence the main purpose of the flasher.

The copper flasher and fly, is running in direct line of the main rigger bait, a spoon, and it can find that same fish that followed and dropped back and trigger the strike on the fly or meat in competition with the flasher.

One advantage of the copper flasher and fly, on the cable, is that it can be dropped quickly on the cable 50 or more feet when a fish strikes the spoon, to keep it out of the way, still running down deep. When the rigger fish comes to the boat the copper is pulled from the release and set in a rod holder, in order to let it run until the fish is in the cooler. Then the ball is brought up while the copper is running free, reset the ball rod and lower it back to 15 to 20 feet and reel up the now drifting copper to the backing connection, reset it on the cable, and send it all back down. The advantage of the copper drifting back there during all this time of netting, icing, and reseting, can grab another hit as it drifts up from the deep and runs free. Saves bringing in the last 100 feet to have to reset a dipsy. Yes it is a form of stacking lines on a downrigger, with some disadvantages in deployment of two rods on a rigger at once, but it is a very effective tailgun bait 100 feet behind the first offerings at the ball, and you can change the depth easily by setting higher or lower on the cable from the ball. The 100 copper will naturally run most baits about 20 to 22 feet deeper than the distance between the ball and the cable release set on the copper backing. Great strike inducer for what we find to be curious lookers, but it's still a pea sized brain we can't begin to understand, even though it is a prehistoric pattern that seems should be easy to figure out.:blink::blink::huh:...

Mark

[Sk8man]

hermit you have a PM Great tip Mark.

Edited January 6, 2016 by Sk8man

[GAMBLER]

I think all this technology has made us better fishermen but some days I causes us to over think things and make it more complicated than it really needs to be.  There are days when trout and salmon will streak way up and hit a bait and days when they want it right in their face.  The tough days are the days we need to be dialed in.   

[Big Water]

Very interesting Mark. Seems like you'd need to be on the ball to avoid tangles if the spoon went.

[Smart Troll]

Smart Troll thanks for the detailed explanation which will likely be beneficial to some newer guys. I'm well aware of the mechanics of fish finders and why the "arch" occurs. The situation I'm referring to is fish moving up/down 20 to 40'.

 

Big Water,

 

The point I wanted to make is the fish arc is formed when the fish is not moving much relative to the boat but you can use that to sort of determine how deep the fish appears to be when at the outer edge of the cone compared to the center of the transducer's cone. If you use the example screen shot below you can see that can be 20 feet or so. For a specific setup it depends on how wide the cone is on your transducer and how deep the fish is (because the cone gets wider with depth).

 

But suppose the fish is swimming along in the same direction as the boat but slightly slower than the boat. You will loose the arc shape and it will be elongated because the fish remains within the cone much longer if it is swimming with the boat. If the boat is going slightly faster than the fish is swimming then that elongated shape will angle up as the fish moves from the edge of the cone to the center of the cone and it will appear like the fish streaked up and then fell away even if the fish remained at the same depth the whole time.

 

**

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[Big Water]

Big Water,

 

The point I wanted to make is the fish arc is formed when the fish is not moving much relative to the boat but you can use that to sort of determine how deep the fish appears to be when at the outer edge of the cone compared to the center of the transducer's cone. If you use the example screen shot below you can see that can be 20 feet or so. For a specific setup it depends on how wide the cone is on your transducer and how deep the fish is (because the cone gets wider with depth).

 

But suppose the fish is swimming along in the same direction as the boat but slightly slower than the boat. You will loose the arc shape and it will be elongated because the fish remains within the cone much longer if it is swimming with the boat. If the boat is going slightly faster than the fish is swimming then that elongated shape will angle up as the fish moves from the edge of the cone to the center of the cone and it will appear like the fish streaked up and then fell away even if the fish remained at the same depth the whole time.

 

 

Well understood

[lost a lure]

All I can say is what you see on the finder is not what is really down there. Drop a camera down and compare it to the finder! You will be surprised.

[Big Water]

All I can say is what you see on the finder is not what is really down there. Drop a camera down and compare it to the finder! You will be surprised.

It's really just geometry.  A moving cone in the water column encountering stationary and moving objects.  Once you recognize that, the observed results are very understandable.

[lost a lure]

It's really just geometry.  A moving cone in the water column encountering stationary and moving objects.  Once you recognize that, the observed results are very understandable.Y

You cant tell me what is down there buy an "arch"

[Smart Troll]

All I can say is what you see on the finder is not what is really down there. Drop a camera down and compare it to the finder! You will be surprised.

 

lost a lure,

 

One thing for sure that hasn't been well stated is that the fish finder screen is a history. By the time the fish arc is fully formed the fish is completely out of the transducer's cone (it started at one edge of the cone and the trailing edge of the arc is the fish exiting at the opposite edge of the cone). So, if the cone is 30 feet wide then the fish is already 15 feet behind the boat when the trailing edge of the arc is formed. That 1 inch (or so) wide arc would have been formed as the fish passed through 30 feet of the transducer's cone.

 

The only pixel that is close to "live" is the one forming on the very edge of the fish finder screen. What is seen at the opposite side of the screen happened some time ago depending on the scroll rate of the screen. If it takes 30 seconds for something to scroll from one edge of the screen to the opposite side of the screen...then what you see on that opposite edge of the screen exited the transducer's cone 30 seconds ago.

[Big Water]

You cant tell me what is down there buy an "arch"

No....but you can understand what possible different scenarios resulted in the display.  There CAN be more than one possible series of events that result in the observed pattern,  Knowing which it was is a matter of probability that can't be determined with absolute confidence without direct observation.

[lost a lure]

lost a lure,

 

One thing for sure that hasn't been well stated is that the fish finder screen is a history. By the time the fish arc is fully formed the fish is completely out of the transducer's cone (it started at one edge of the cone and the trailing edge of the arc is the fish exiting at the opposite edge of the cone). So, if the cone is 30 feet wide then the fish is already 15 feet behind the boat when the trailing edge of the arc is formed. That 1 inch (or so) wide arc would have been formed as the fish passed through 30 feet of the transducer's cone.

 

The only pixel that is close to "live" is the one forming on the very edge of the fish finder screen. What is seen at the opposite side of the screen happened some time ago depending on the scroll rate of the screen. If it takes 30 seconds for something to scroll from one edge of the screen to the opposite side of the screen...then what you see on that opposite edge of the screen exited the transducer's cone 30 seconds ago.

I have to agree with that. You can make an "arch" with a jig.

[lost a lure]

No....but you can understand what possible different scenarios resulted in the display.  There CAN be more than one possible series of events that result in the observed pattern,  Knowing which it was is a matter of probability that can't be determined with absolute confidence without direct observation.

There are several scenarios. The fact is that what you are seeing is not always what anyone thinks it is. YOU probably think it is a fish because that is what you want to see. The video shows it directly. A stick floating in the water shows on the sonar.

[Big Water]

There are several scenarios. The fact is that what you are seeing is not always what anyone thinks it is. YOU probably think it is a fish because that is what you want to see. The video shows it directly. A stick floating in the water shows on the sonar.

I agree and FULLY understand.  My intent wasn't to debate sonar observations.

[lost a lure]

On the other hand if your seeing marks on the screen you want to your spread in it whatever it may be

[Sk8man]

One of the things I've noticed over the years is that VERY frequently the fish I actually catch I didn't mark at all beforehand suggesting that they may be way outside the cone angle so sometimes spending most of your time squinting at the screen may not be as productive as actually messing with your equipment and doing a variety of things with it and not totally relying on screen shots. My grandfather used to catch a hell of a lot of fish in a rowboat without anything but the line or wire in his hand....sometimes we forget to concentrate on basics.

[Big Water]

One of the things I've noticed over the years is that VERY frequently the fish I actually catch I didn't mark at all beforehand suggesting that they may be way outside the cone angle

Sk8man,

 

I would bet 95+% of the fish I catch I didn't see on the screen.  Steelhead seem to be slightly more predictable.  What I've observed time and time again over the years is when I see fish and drop my riggers 30-40' under them, I catch fish.  I understand rigger blow-back, cosines of angle and hypotenuse  so let's not argue about this and perceived depth.

[Sk8man]

Geez Big I wasn't in any way "arguing" anything just throwing in my two cents and my last comment was basically directed at all the technical stuff. I think Brian said it right sometimes we "overthink" things and I can be as guilty of it as anyone   I for one am glad you brought up the topic to explore.

[Big Water]

Geez Big I wasn't in any way "arguing" anything just throwing in my two cents and my last comment was basically directed at all the technical stuff. I

Sk8man,  that certainly wasn't directed at you.  You seem like a real straight shooter and I do appreciate your comments.  I just didn't want someone trying to explain blow-back to me.  I've thought that when I drop the riggers, maybe a fish sees it as an escaping baitfish, follows it down, and then at some point hits the lure.  What I'm not seeing, at least to the same degree, is fish hitting when I raise the riggers.  Like I mentioned, dropping down under them by a substantial distance has yielded many strikes.   

[Silver Fox]

I have a migraine

[momay4000]

I have a migraine

LMFAO!! It has to be the first time in LOU history that the word cosine was used in an LOU post.

[Big Water]

LMFAO!! It has to be the first time in LOU history that the word cosine was used in an LOU post.

  Sorry!!!   My analytical side is showing (most would say overly analytical)

[Smart Troll]

Big Water,

 

Clearly I am "overly analytical" too and when I elaborated on some of the theory I certainly didn't mean to imply anything about your understanding of it all...after all I can see you are  "Pro Member"

 

Your original post about fish streaking up on the fish finder screen just brought to mind the theory that when fish appear to have streaked up from 20 feet or more they almost certainly traveled lots less than that through the water column because of the way the fish finder cone works. I appreciated your question because it gave the opportunity to think it all through again and being over analytical it is easy to get carried away with some of the posts. It was kind of fun to put it all down in writing...but I guess that is just the analytical nerd in me.

[Xxx]

I guess I'll stick my $.02 in this TMI thread, I agree with Big Water on this theory, most of the fish I catch were never on the sonar. With boards out and long lines what is the sonar doing? Giving you an idea where the fish are in the water colum.