Finding fish arches

[waterinthefuel]

Ok, so I get my new FF, install it, we know it clicks and drives me up the walls. What about finding fish arches? I believe I've only seen a couple. I can't really tell. I know my transducer is installed right. It seems that the only time I get definable fish arches is at a particular boat and chart speed.<br /><br />Is this normal? When I select "fish symbols" I get little fish symbols all over the screen, but flip it to "off" where only arches appear, and I never see arches. I've only seen a couple, and they were questionable, although I do believe they were due to their suspended nature above any cover in the area.<br /><br />Anybody got an suggestions on how to help see fish arches?

 

[crab bait]

Re: Finding fish arches

i can't wait to answer this one..

 

[SingleShot]

Re: Finding fish arches

This was taken from Garmins FAQ<br /><br />When the Fish ID is turned off, you will see an actual representation of the sonar echo. The sonar pulse is a convex wave that goes out of the transducer. The only way the unit will show a perfect arch or half moon is if the fish enters the front of the cone, goes straight toward the center and out the back. This would cause the echo to get closer toward the center, causing the arch. If a fish enters the cone and goes out the side, you may get a partial arch or just a black spot on the screen. When using the unit with the Fish ID off, set the gain to around +2 and use the split-screen zoom to make it easier to see the fish (although you still may not see a perfect arch). <br /><br />I hope this helps, all sonars I know of work the same.<br /><br />SingleShot

 

[waterinthefuel]

Re: Finding fish arches

Singleshot, I appreciate the help. I did, through experimentation end up with my gain set to +2, but I didn't think of using split zoom.<br /><br />Thanks alot.<br /><br />Here is another question:<br /><br />What, on average, do you think the chances are that a fish symbol is actually a fish? I know it all depends, but lets say you are in 20 feet of water, no structure, then at 10 feet you get a fish symbol. Is that probably a fish, or just a false echo?<br /><br />Again, I appreciate any help I can get on this.

 

[NOSLEEP]

Re: Finding fish arches

if its an arch, its a fish. If its on fish ID<br />who knows!

 

[jtexas]

Re: Finding fish arches

Another inexperienced FF user here. Don't want to hijack water's thread, but here's a follow-up question: say a moving boat passes over the end of an underwater treebranch that's sticking out perpendicular to the direction of travel and reaches close to the center of the cone - does that make an arch on the graph?<br /><br />I'm still using the fish ID but I've been advised to learn to read the echo. Is there a school somewhere that teaches this? (besides the one in Annapolis )<br /><br />thanks,

 

[NOSLEEP]

Re: Finding fish arches

The full arch is a result of a fish passing<br />completely under the cone. The fish's bladder<br />interrupts the sonar and results in a complete arch.<br />Weeds can be mistaken for schools of fish but<br />do not show arches.

 

[crab bait]

Re: Finding fish arches

i have a liquid graphpaper unit ..a zercom.. it has no fish symbols..<br /><br />i've had this unit 3 years.. <br /><br />i have NEVER seen an arch... an only seen SOMEWHAT of a 1/2 arch twice..<br /><br />all i see is dots an blobs... <br /><br />i consider them to be depth & FISH HABITAT FINDERS..

 

[snapperbait]

Re: Finding fish arches

Dots and blobs is usually bait on mine Crabby... Break out the sabiki rigs an load up....<br /><br /> "fish habitat finders".. so true....

 

[crab bait]

Re: Finding fish arches

but ALWAYS ,, when driftin',,, it's a total blank srceen...

 

[Boatist]

Re: Finding fish arches

I see arches and half arches all the time. To see arches you must get returns from the fish. Since the fish is like a stealth fighter you have to get a strong return. Turn the sensitivy up until you are getting false reading scattered around your screen. Then turn back down until mostly clears up. Set this way you will also have lots of surface clutter but that is what you want. You will never see a fish on the surface anyway. <br />With a standard 200 khz 20 degree transducer fishing in 30 feet of water then you are looking at a 10 foot circle on the bottom. The transducer must be pointed straight down when the boat is sitting in the water. Since most sterns are lower in water than bows the transducer will not line up with the hull. If you line transducer up with the hull then often you will see the start of the arch but not the back of the arch. With a 50 khz 45 degree transducer you see a much bigger circle under the boat and transducer installation is not a important. You will get better arches if you use 4 times zoom or some form of bottom lock. In deeper water you will get better arches but must turn up sensitivity to point get some false echoes in the bottom 1/3 of the water.<br /><br />You must go slow, trolling speed. To draw an arch you must get enough returns to draw the arch. Since in 30 feet of water if you move 10 feet you no longer see the fish, then you must go slow enough to get enough returns off the fish to draw your arch before going 10 feet. That 10 feet is if the fish is right under the center of the cone, off to either side and you will not see the fish for 10 feet.<br /><br />If you go over a tree with the branch up off the bottom it will make a nice arch. Very hard to tell if it is a fish. On some fish like Salmon if you turn off your gray line {white line or Color Line} then you can actualy see the fish's cavity or blatter and know it is a fish. A bush under water offten looks like a school of bait fish.<br /><br />Some clubs that run Tournaments will have a expert come in and give tips how to get more out of your depth finders. Some clubs will allow members to bring guest or public to attend at a fee. The Class I have been to have all been very good. Most of these experts are also selling a video tape or book and these also help.<br /><br />Lowrance has a totor that tell why fish arch that may help.<br /> http://www.lowrance.com/Tutorials/sonar/sonar_tutorial_10.asp

 

[crab bait]

Re: Finding fish arches

thanks BOATIST,<br /><br />just like i said ..'fish habitat finders'.

 

[waterinthefuel]

Re: Finding fish arches

Great info, thanks guys.

 

[nightstalker]

Re: Finding fish arches

I've owned three different types of ff, and the only "real" arches I have ever seen are the ones shown in the owner's manual.<br />Stalker

 

[NOSLEEP]

Re: Finding fish arches

90% of the fish are in less than 10% 0f the water.<br />I see fish arches regularly on the lakes I fish.<br />I do not use fish ID . I set gain at +3 and depending<br />how deep the water is even higher.<br />I use Garmin 160. Works great.

 

[imported_JD__]

Re: Finding fish arches

I have a recording sonar and have saved some great soundings of mostly striped bass. These arches are unmistakable . How do I know they were fish? I caught fish jigging and casting in the school while I was watching them on the screen. For those of you who haven't seen arches, send me your email or tell me where I can post the pictures. Better yet, a guide I know here in Virginia posted some of my recordings along with his. Check them out at:<br /> http://www.theshadtaxi.com/picssonar.html <br /><br />JD

 

[dakotashooter2]

Re: Finding fish arches

In order to get an arch the fish has to pass through the full beam of the finder. If you read a flasher manual you will understand why the signal comes as an arch. The beam is cone shaped getting larger the further it gets from the transducer. As a fish enters the edge of the beam it is at the farthest distance from the transducer (the deepest part of the arch) as it reaches the center of the beam the distance to the transducer is at it closest(higher in the water column. As it passes to the outer edge it is once again the farthest away from the transducer.While the difference in distance is really very minor calibration of the finder magnifies it enough to make signals visible.Think of it this way. You have a triangle. If you extend the outer lines nearly strait down they will be longer than the bottom line of triangle. Connect the dots and you have an inverted v or "arch". If a fish passes through the outer edge you will not get the classic "arch".A fish hovering below your finder will not show as an arch. If it changes depth while passing through you may not get an arch. If it is a small fish you may not get an arch. In most cases if you are getting a full arch you are probably encountering a school of fish as only a small % will likely show as arches. The majority will be other marks on the finder. Your pixel count will also determine if you get an arch. If 1 pixel = a 6" fish a 12" = 2 pixels. Not enough to form an arch.<br /><br />Often bottom objects are not the same shape they appear on the screen for the same reasoning.

 

[waterinthefuel]

Re: Finding fish arches

I am learning so much. This is amazing. I swear every post opens up a new horizon for me. By golley I am going to see an arch before I die! LOL

 

[Troy_from _Oz]

Re: Finding fish arches

For what my 2 cents are worth, I think that Boatist has the best methodology - which was:<br /><br />"Turn the sensitivy up until you are getting false reading scattered around your screen. Then turn back down until mostly clears up. Set this way you will also have lots of surface clutter but that is what you want."<br /><br />I have a concern that with these new specky fishfinders out there - the phrase that they probably "catch more fisherman than fish" might apply here. (yep - i think everyone should ho back to sounding with a lump of lead attached to a rope ). What you should be looking for are returns (or groups of returns) that are not on the bottom, and that are in the part of the water column that you migh expect fish to be located. If you think about whats going on inside the fishfinder (when fish id is on) it will help to realise what it is that is being displayed. The echo sounder sends out a pulse (or multiple pulses) and receives some pulses back. Some of these will be the bottom, some will be surface clutter and some will be other things in the water column. How does it go about deciding if it is a fish? My guess would be that (after some processing) it has a simple alorithm that searches for returns that arent in the bottom trace, and arent in the surface clutter. I would then guess that if the returned signal is higher than some predetermined threshold (in tems of signal strength) then it flags that as a possible fish. If it were me programming the logic, I would then do a search for returns at about the same depth either side of the one you are looking at. If there are multiple returns either side - i would attach a big fish symbol to it. If there are no returns either side - normal fish symbol! <br /><br />The downside to all this is it has to use some simple logic to decide what returns are from fish, and what are from air bubbles or other things in the water column. If it's a really noisy environment - you might get lots of returns that show up as fish. If you were just looking at the returns, then you would be making the decision about what returns are likely to be fish and which ones arent. <br /><br />So its my thought that fish id's basically take the thought process out of reading the display. this is both a good thing and a bad thing. do you really want to have to decide about all this considering that it will probably be taking your mind off your fishing - id say sometimes not. <br /><br />With a bit of practice though, I think it's very valuable to be able to use the other information that you can get out of the clutter! - if that makes sense???<br /><br />I think that technology is a great thing (for average Joe's like me), but it should be something you use to suplement your other sources of information. - as Crab bait said - they are probably the most use as fish habitat finders. <br /><br />I appologise for seeming a bit sceptical about what goes on inside black boxes like this - maybe its just that i dont understand them well enough... <br /><br />I think my 2 cents worth have well and truly run out now. cheers - troy

 

[crab bait]

Re: Finding fish arches

Originally posted by waterinthefuel:<br />I am learning so much. This is amazing. I swear every post opens up a new horizon for me. By golley I am going to see an arch before I die! LOL

yeah,, don't hold your breath......