Depth,Fishfinder,Structure

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01-12-2012, 09:39 PM
Rick O Reel

Depth,Fishfinder,Structure
Today, 09:28 PM #1
Rick O Reel
http://www.crappie.com/crappie/image...ser-online.png Keeper

Join DateNov 2010Locationspartanburg, south carolinaPosts38

http://www.crappie.com/crappie/images/icons/icon1.png Depth,Fishfinder,Structure

Hello Everyone,
I recently got a lowrance hds 10, structure scan,side image,down scan unit been trying to learn all I can reading book, internet ect. I wanted to get opinions from you all on CDC. When boat is moving over structure aprox. 4- 8 miles per hour and structure is first seen on screen on right hand side of screen moving to left hand side of screen. Where is exactly the structure under boat, if I threw a marker out at my transducer as SOON as I first see it on the right hand side of screen would the lead and string land on top of structure.

Also structure scan looks beautiful if you are moving over structure ,but if you stop over know structure is does not look the same . Do you have to be moving for it to work right. I did read that for a fish to arch on sonar you had to be moving . But the tree or structure does not show on structure scan mode sitting still. Is this normal ?
01-13-2012, 12:17 PM
brushnjigs

That would depend if you have the ducer set level to the water line (scum line) on the boat, as this is where it should be set and not level with the hull. Then it would be difficult to guess how far over the cover is. If you are seeing cover look for the fish and punch the waypoint button. It will take you awhile to use up 5000 way points
01-13-2012, 02:45 PM
rnvinc

Quote:

Hello Everyone,
I recently got a lowrance hds 10, structure scan,side image,down scan unit been trying to learn all I can reading book, internet ect. I wanted to get opinions from you all on CDC. When boat is moving over structure aprox. 4- 8 miles per hour and structure is first seen on screen on right hand side of screen moving to left hand side of screen. Where is exactly the structure under boat, if I threw a marker out at my transducer as SOON as I first see it on the right hand side of screen would the lead and string land on top of structure.

Also structure scan looks beautiful if you are moving over structure ,but if you stop over know structure is does not look the same . Do you have to be moving for it to work right. I did read that for a fish to arch on sonar you had to be moving . But the tree or structure does not show on structure scan mode sitting still. Is this normal ?

In the 2d image and the DI image...
1. the most recent data is to the far right of the screen
2. everything to the left is "history" that the xducer has already passed over

In the SI image...
1. the most recent data is at the top of the screen
2. everything under that is "history" that the xducer has already passed over....

In sonar....the xducer sends out a ping (several per second)....reflections are then recognised as distance( in time) from the xducer....then the processor calculates this "time distance" into ft distance.....then the unit processes that data into something we can understand...and then plots that data into a thin strip at the most "recent data" place (right part of the screen on 2d and DI...top part of the screen on SI)

The next ping goes thru the same process in the unit...then the unit "stacks" this newest "recent" data on the screen and pushes the previous ping's data in the "history" of the image.....

Over and over these pings are sent out...processed ....plotted on the screen into the most "recent" section of the screen...pushing previous ping data into the "history" section of the screen...

This is how sonar (in intermitant pings) is rendered into an "image" (picture like) that we can understand on the screen...

Because the DI and SI sonar beams are "fan" shaped...some movement is generally neccessary..or the xducer would just pin and re-ping the exact same "fan" shaped section of water over and over...making the image looks stretched or skewed....

Setting the chart speed to match the boat speed will allow the xducer to ping a new "fan" shaped section of water at each ping....the unit will then "stack" those successive pings into an picture like image....

Rickie
01-13-2012, 09:39 PM
vic n

LOL.....in other words....if the image is scrolling right to left, you are either looking at the DI or traditional sonar. Each of these has a cone shape. So imagine a cone with the tip at your transducer and it spreads as it goes deeper. If you are looking at DI, it may have a 45 degree angle. There are several threads here that will give you a chart that will tell you how wide that cone is at the depth you were in. In other words, if you were in 20' of water, you may have a 20' coverage area with whichever cone you were using. So you go over a piece of structure and throw out a marker. That marker will be in line with the structure, but the structure itself can be anywhere on that line. So if you have a 20' wide cone, the structure should be somewhere within 10' either side of your marker.

When you look at SI or SS, the structure will be directly in line with the trans, but you have to figure out how far left or right it is from the boat. Hope some of these responses help.