Q&A thread for Fishfinders and GPS

[BassProAddict]

Here's one:

Here's a surefire (Contact Us Please) question:

So you see the display on the screen right...so when you're looking at it, is the image you see infront of you? Example:

AAA BBB CCC

D E F

So is AAA in front of you but to the left of you?

Is BBB in front of you directly?

Is D deeper than AAA but under it?

So you know it's left of you,straight at you and right of you.You know DEF are deeper but for each of these, how do you know how far IN FRONT OF YOU they are?

Go easy on me guys.Electronics noob question.

[PerchJerker]

I assume you're talking about your sonar or graph display.

What it shows is what is under the transducer. Assuming the transducer is mounted at the transom or on a bow mount trolling motor, it shows you what is under the back or front of the boat.

The right side of the display is what is currently under the transducer, as you get farther to the left side of the display you're looking at history (what was under the transducer a few moments ago). It shows you depth, like D under A in your example, but it doesn't show you left, center, or right ---- it only shows you what is (or was) under the transducer.

Hope that helps, good luck. There are probably some good sonar tutorials on line to help you out. I'd suggest you try snooping around on Lowrance and Vexilars homepages, they seem to have good info on them.

[BassProAddict]

Hi.I'm talking about Lowrance X96es and Humminbird fishfinders etc.

I've tried looking at Lowrance websites and even downloaded several manuals but to my shock and surprise, no "how to interpret/read fish finders" section.

I'm trying to digest what PerchJerker said.So if it doesn't show you left or right of you, how do you know where to cast, how far and how deep? How do you divide the scroll of the screen from history(what was under) and present (what IS under)? Can you pause/hold the image and cast right away where a fish arch will show up? But then again, where is that fish arch in the water (left?right?)?

I expected the answers will further confuse me but if I hang on, I'll understand it eventually.

Like I mentioned,electronics noob here.

[Deitz Dittrich]

BPA- You need to find someone who understands a graph and can show it to you. Its veryhard to explain. Depthfinders do not show you right and left. only what is underneath you.. they do however go out insomewhat of a cone, and cover slightly more than is just underneath you. If you however know the structure you can make assumtions as to what it is reading.

What is underneath you is on the furthest right part of your screen. As a new image take place it pushes "rememberd images off to the left of the screen unitll it falls off. IT is not "Left " of you, its just remembered images.

[walleyewild]

BPA, google hightech fishing or Bruce "doc" Sampson.

There is more info on that site for using your locator and gps then you can shake a fishing rod at.

[solbes]

I found a good explanation at the fish finder depot website. But to partially answer your questions, the cone angle of your transducer will determine the size of the search zone. This is also dependent on the depth you are fishing. For example, an 18 degree cone angle will rougly divide your depth by 3 to get the diameter of the search zone. If you are in 18 feet of water, the sonar will seach the bottom in a 6 foot diameter circle. At 9 feet of depth it will only be a 3 foot circle. Find the cone angle of your sonar to determine this.

There really is no right/left capability of normal sonar graphs, outside of the above search circle. What you see is either right below you (on right side of screen) or behind your boat in the track you took (scrolling history as you move left). Keep in mind that what is reported on the graph does not tell you where in the search circle the item was. As a tip, move your scrolling speed to the highest setting and make sure your fish ID is turned off (you'll get used to this).

Fish arches have to do with a little trigonometry. As the fish first enters the cone, it is further away from the transducer (think hypotenuse) than it will be when it is directly underneath the 'ducer. (Even though the fish remains at the same depth) Thus it appears to raise in depth. The opposite happens as it moves from the center of the cone to the opposite edge, it appears to get deeper because it is further away (hypotenuse again).

To further confuse you, there is a relatively new technology called side imaging sonar. This will take a top down picture of the bottom and will give you information on the left and right side of your boat. Still pretty spendy though and I'm sure this technology will improve in the coming years.

[BassProAddict]

Very informative though confusing.I'll get it soon.

So ok, here are some follow up questions:

Established fact:

No left of me or right of me...just under or what I passed.

Q:So the only way to "investigate a spot is if I've passed it or I'm directly on top of it?

Q:So the structure I then "discover" is behind or under me so I either cast from the rear of the boat or turn around and recall what was displayed a while back?

Q:So the FF will display the following real time items only:Depth Right Now,Temp Right Now and "stuff" directly under me (right portion of the screen)

Q:So all you you FF users know how to work these information along with cone angles,"stuff under you" interpretation?Man you guys are wizards!

[hanson]

Thats "basically" it!

If you are trolling or moving forward, what shows up on the right hand side of your depthfinder is what you just passed over. That information continues to move to the left as the new information appears on the right side of your depthfinder.

In regards to the cone angle, the deeper the water you are in the more of the lake (left & right) you will see on your depthfinder. However, it will all appear on your depthfinder like it is right underneath you. So you might see 2 fish on your depthfinder but one is to the left of the boat and one is to the right of the boat, although they look like they are swimming together on your screen.

In shallow water, less than 10', you might only be looking at a 3-4' wide area directly under your boat. The deeper you get, the wider the area it is you are viewing.

[BassProAddict]

Starting to comprehened it.

So wait, what a fishfinder mostly tells you about arches or bait balls is HOW FAR they are from the transducer and nothing on direction correct? It does tell you what's under you interms of structure hardness and type.Aside from vertical jigging and drop shotting, you can't really cast directly under you right? And since most of the FF's reported images are from underneath you, you have to circle around a spot you liked, remember what it was (or pause it) and then you cast away?

[PerchJerker]

Sounds like you are mostly interested in casting???

One way to use a sonar in that regard is to locate a piece of structure - an underwater point, an inside turn in a weedline or breakline, an underwater hump, a boulder or a rock pile, etc - find the structure with the sonar, toss a marker buoy, then back off and fish using the buoy for reference.

Another way is if you're working a breakline or a weedline, you can figure out the depth at the bottom, then position your boat deeper, and try to follow that depth to work along the weedline or breakline.

[B3B]

With the newer side vision technology it is now possible to look to the sides. With a Humminbird Quadra Beam unit and transducer you can see to the sides out 2 X what ever your depth is (normal units have a 1 for 1 ratio or less). If your in 30 feet of water, you will see 60 feet in width, and it shows what is at your right, and what is at your left.

If you spend the cash for their High Def. Side Scan units +/- $1000.00 (#797) to $3000.00 (#1197), you can see out to 200+ feet to either side.

You can do a google search for Hummingbird Quadra Beam, Or Hummingbird HD Side Imaging to find out more. Cabela's also has them. The 1197 comes out on the store shelves in Feb, so it's not in catalogs now.

Actually on ALL depth finders, except those using "Flasher" technology like a Vex uses, everything you see on the screen is past history. Flashers give "real time" information of what's going on underneath you at that instant in time.

Some units like the older Garmin I use now, give you the option to show a "Flasher Window" on the unit just to the right of the regular screen so you can see a fish that will be coming up on the regular screen about 2 or 3 seconds before it actually appears as an arc or a fish symbol.

[PerchJerker]

Quote:

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about 2 or 3 seconds before it actually appears as an arc or a fish symbol

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You said this was on an 'older garmin unit'. I don't think any units, even the original sonars, ever had a 2-3 second delay. Paper graphs maybe, but not LCDs. The only way there'd be a delay this long is if you waited for the full symbol to be displayed in the middle of the screen --- but if you read the right edge of the screen there isn't a delay like this.

New sonars don't have any delay, they are instantaneous. Ain't technology wonderful

[Ralph Wiggum]

Quote:

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New sonars don't have any delay, they are instantaneous. Ain't technology wonderful

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You'd be hard pressed to get a flasher guy to admit that, but it's true!

[B3B]

I did mean before the entire arc or symbol showed sorry !!

[solbes]

Quote:

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Starting to comprehened it.

So wait, what a fishfinder mostly tells you about arches or bait balls is HOW FAR they are from the transducer and nothing on direction correct? It does tell you what's under you interms of structure hardness and type.Aside from vertical jigging and drop shotting, you can't really cast directly under you right? And since most of the FF's reported images are from underneath you, you have to circle around a spot you liked, remember what it was (or pause it) and then you cast away?

---

Your first point was dead on. It tells you that something gave a return at a certain DISTANCE from the transducer. It could be ANYWHERE within the cone angle (left, right, front, back) at that specific distance from transducer.

Your also correct that it does give a good indication of bottom hardness. Try to watch for transitions of hardness (solid greyline to black), as these will sometimes be likely hang outs for fish. It will also give you clues about what structure you are seeing (maybe a hard rock or log, maybe it's just a clump of weeds, etc).

And to your final question, you have a couple of options. You can drop a marker bouy as suggested. You could also mark the spot with a GPS (maybe get a combo GPS/Sonar!). I might mark the location if I see something I really like, but usually the information just goes towards putting the puzzle together. What depth are the fish relating to? Bottom type? Relation to weed line, bait fish, etc. I use it more to target the high percentage areas of the lake than to pinpoint specific locations. Paying close attention to depth, bottom type, and weed lines will likely produce better than only looking for fish returns/arches.

One final suggestion is that trolling cranks or dragging rigs/jigs makes it easier to target those fish you are seeing. No circling around to get to those spots.

[BassProAddict]

Excellent education I'm receiving here

So do most electronics guys here who have FishFinders and FF-GPS combos rely on those "Fish Arches" to locate possible within-the-cone-vicinity-fish or to mostly map out the bottom and give depth/temp/thermocline locations?

I've see that Humminbird Side Imaging and yes it is quite impressive.

[BobT]

A little of both. Primarily to locate or stay on structure but also to determine if there are fish in the area. The thing to remember is that a sonar unit is looking at an extremely small area below the boat. Not seeing fish arches doesn't mean they aren't there. Also, interpretation of what you are seeing can very based on experience and sonar quality.

Bob