Fish finder help?

[bassmaster84]

Hi guys

So I will be purchasing a fish finder soon for my soon to be inflatable...

Assuming that the transducer gets mounted to the trolling motor at the back via the mounting kit behind the motor housing, how exactly will the display work?

I know it gets read from right to left, (right being the oldest data, right? LOL) but where exactly will the sonar be shooting i.e. what area will I be seeing on my screen? Directly underneath the trolling motor with lets say a 80 degree angle? or am I assuming wrong... Don't want to be casting into the deep dark nothingness :eusa_think:

Any handy artist out here that can draw me a picture? :eusa_whistle:

Any help would be appreciated!

[Jim_From_Zim]

It all depends on the type of unit you want to put onto your boat. They all have varying degree's and types of scanning. Best would be to do some google research versus the amount you wish to spend.

As an example on the Dragonfly unit I have which has downscan and sonar capabilities, these are the types of 'cone's' you can expect to cover. (different units will give different cones according to the types of transducers they use, as well as where the unit sits in the range of quality and options)

Downscan on the Dragonfly:
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and sonar:
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Typically, the info scrolls from right to left, which would make the right the newest info and left being the oldest.
Learning how to read the information the unit is throwing at you is the trick. Again, google can help you here to a point, but a lot of it comes with trial and error in knowing what info it gives you in relation to the terrain.

[Riprap]

bm84 - have a look at this through the pages:

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[dollar]

hi gents, further help please. jim-from zim has post some pics showing the coverage area with dotted lines, lets say, on the left side is a tree and on the right side a huge rock, both within the scan area, how does this info appear on the screen?

[bassmaster84]

Thanks Jim and Rip! I will be starting out with a basic little unit, to familiarise myself with fish finders at first... So no need to worry about understanding downscan now... lol! That article you posted rip, answered most of my questions thanks! And i guess like Jim said, one would have to spend time with it on the water to see what the info says!

[Riprap]

Pleasure boet, but be warned, they are like woman.....if you push the wrong buttons, you get the wrong result.....hehe.

[bassmaster84]

HAHA Rip, just mentioning anything fish related to my wife is like pushing a wrong button... I had to stop saying "That dam will definitely have big bass' when we watch movies! HAHAHA!

[Q]

hi gents, further help please. jim-from zim has post some pics showing the coverage area with dotted lines, lets say, on the left side is a tree and on the right side a huge rock, both within the scan area, how does this info appear on the screen?

You must remember that the sonar works on echo's. It transmits a pulse and then measure the time it takes for the echo's to return. I say echo'S because there will be more than one.

Also, it does not know where the echo's comes from (left, right, etc.), just the fact it received one.

And than echo's from softer material comes back with less power than echo's from hard material.

If you stand dead still in the water, you first will get an echo from the tree (because it is closer/ shallower) and then the bottom. What you will see is a multi depth display. with the tree as a line first and the bottom a second, deeper line(simplified explanation, there is normally many lines, your rock on the one side will also produce a line). The tree will be in a different colour or grey scale than the bottom. This colour is determined be the strength of the returned signal.

To pick up the tree profile properly, you have to move over it.

Dual scan:
As you would have seen from the articles, dual scan is two different frequencies creating to different size cones (normally 20 and 60-80 degrees). In you tree example, the narrow beam might miss the tree at first, only returning the bottom in more details. Switching to wide scan will see the tree, but you get less accuracy where it is.
OTOH. Dual scan is actually only helpful if you fish very deep (sea), as the wide beam will be too wide for the bottom and will return signals from a very wide area.

Chirp (as used by the Dragonfly and other side scanners):
From what I've read about it, I understand the following:
The chirp transducer uses variable frequency, so it starts at one frequency to get a wide beam and then change the frequency gradually (higher I think?) and subsequently narrowing the beam, during that time making continuous readings and from all that readings it builds up the picture you see.

[dollar]

thanks Q, its making more sense to me, just intalled a sonar and played with it once last weekend. was impressed with the unit compared to the old garmin 140 but for some reason i was trying to find the "almost 3d pic" shown on the box from some know structure in the water. will keep on playing tomorrow.
btw you all have an awesome weekend and land pb's