Understanding Range ?

So let say you are shotting out 100ft left and right and the boat is setting in 6 inches of water. If there is a rock at the edge of the graph one would believe it to be 100 ft or so from the boat. Right!!

Now lets say you are still on 100 ft range and setting in 50 ft of water. If the rock is still on the edge of the graph is it 100 ft from the boat or 50 Ft from the boat?

Now say you are in 90 ft of water, Black almost to the edge of the graph and there is a rock on the edge of the graph is it 10 ft from the boat or 100 ft from the boat while still on 100 ft range ?

Not sure why this poped into my head but someone set me streight....

721 ProXP

I've wondered the same thing... Hope one of the experts answers this.

I believe it is still 100' from he boat. I don't think depth has any bearing on side scan. At least thems my thoughts. I'm sure Doug or Mike will set us straight soon

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Lassiter &raquo;</td></tr><tr><td class="quote">I believe it is still 100' from he boat. I don't think depth has any bearing on side scan.</td></tr></table>

Not Doug or Mike...but I'd agree with you. I believe that it will be 100' away still. Just that at a deeper depth everything that you see from the water column out to the edge should be crammed in a tighter picture (with all objects being smaller). That's my thoughts on it. http://www.bassboatcentral.com/smileys/thumbsup2.gif

If that's the case, in 50ft of water on a 100' range something would have to be pretty big to show up I would think. On an 898 with 100 ft represented by 2 inches of screen, an object would have to be roughly 12ft to be 1/4 inch on the screen...

Pro xp if the rock or boulder shows up on the outside edge of the screen
it will be that distance from the boat regardless of the depth.If you are scanning
100 ft. it will be 100 ft from the boat regardles of depth. Example set your machine
to scan 100 ft wide find a object 70-100 ft away.Switch scan width to 50 ft object
will disapear.The closer the scan width the bigger the object will appear on your
screen.I like to scan 50 wide on my 997 looking for brush piles or specific detail. http://xs-s.com/zf/images/smile/emthup.gif http://www.bassboatcentral.com/smileys/smile.gif Hope this helps. Gary

Lets look at this, if you are on a 100 ft scale, in 75 foot of water(being 75% of the screen is black) an object 100 ft away would show up at the edge ( what ever size it is, being big enough to see, not the point though) another object under the boat actually would be at the 3/4 or 75% across the screen where the bottom starts showing up.

Case 1
If this is the case then the object under the boat would show up 75 ft from the boat out on the screen.

Case 2
same deal as above but if an object is 100 ft from the boat and shows up on the edge, and an object under the boat show at the bottom, 3/4 across the screen then the 100 ft between the 2 object wouldn't be to scale in the 25% of the screen that shows bottom.

Case 3
Same as above. an object below the boat is shown 3/4 out on the screen on the bottom, then an object 25 ft from there would be on the edge of the screen. 100 Ft from the boat from object to transducer, yet only 25 ft from the side of the boat.

Case 4
Your in 100 ft of water 100 ft away from the bank. The bank slops at a 45 deg angle down under the boat there's BIG BOULDERS laying all over the bottom. I would think that they wouldn't show up being that the screen is black all the way to the bottom.

Not that you would run a unit like this just trying to figure out where objects are.

Does anyone else see my confusion!!!

721 Pro XP


Modified by 721 Pro XP at 7:56 AM 12/29/2010

Here is an image.
http://i150.photobucket.com/albums/s...Humminbird.jpg

If X marks 100 ft out from the boat.

if Y marks the bottom which is around 50 ft Then does Z mark 75 ft out from the boat?

If anything on the edge is 100 Ft away then the scale has to screwed close to the bottom edge.

Anything out 10 to 20 ft from the boat, left or right is going to show a minimum of 50+ ft from the boat. So the scale is going to be off the way I see it.


721 Pro XP


Modified by 721 Pro XP at 8:41 AM 12/29/2010

Do you use Humviewer?
If you do, stop a recording in the SI view and put the pointer on the center line and then move it to the sides while watching the readouts at the bottom. You will see how the distances are represented.

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by 721 Pro XP &raquo;</td></tr><tr><td class="quote">Lets look at this, if you are on a 100 ft scale, in 75 foot of water(being 75% of the screen is black) an object 100 ft away would show up at the edge ( what ever size it is, being big enough to see, not the point though) another object under the boat actually would be at the 3/4 or 75% across the screen where the bottom starts showing up.

Case 1
If this is the case then the object under the boat would show up 75 ft from the boat out on the screen.

Case 2
same deal as above but if an object is 100 ft from the boat and shows up on the edge, and an object under the boat show at the bottom, 3/4 across the screen then the 100 ft between the 2 object wouldn't be to scale in the 25% of the screen that shows bottom.

Case 3
Same as above. an object below the boat is shown 3/4 out on the screen on the bottom, then an object 25 ft from there would be on the edge of the screen. 100 Ft from the boat from object to transducer, yet only 25 ft from the side of the boat.

Case 4
Your in 100 ft of water 100 ft away from the bank. The bank slops at a 45 deg angle down under the boat there's BIG BOULDERS laying all over the bottom. I would think that they wouldn't show up being that the screen is black all the way to the bottom.

Not that you would run a unit like this just trying to figure out where objects are.

Does anyone else see my confusion!!!

721 Pro XP&lt;br /&gt;&lt;br /&gt;
Modified by 721 Pro XP at 7:56 AM 12/29/2010</td></tr></table>

If you are in 100ft of water as in your last scenario and you are scanning 100ft out and at that distance it is 100ft deep also, then the screen should be completely black(water column).

Just because an object is 3/4 of the way out (on the screen) doesn't represent 75ft when scanning 100ft. You have to recognize that the 0-100ft scan distance starts where the water column ends and goes out to the edge.

In other words...divide only the part showing the bottom into 4 equal parts and that should represent the 25-50-75-100ft points.

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Wayne P. &raquo;</td></tr><tr><td class="quote">Do you use Humviewer?
If you do, stop a recording in the SI view and put the pointer on the center line and then move it to the sides while watching the readouts at the bottom. You will see how the distances are represented.</td></tr></table>

No I have apple computers. I have boycotted Bill Gates ever since he wouldn't loan me money for a new boat. LOL

721 ProXP

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by db_db &raquo;</td></tr><tr><td class="quote">

If you are in 100ft of water as in your last scenario and you are scanning 100ft out and at that distance it is 100ft deep also, then the screen should be completely black(water column).

Just because an object is 3/4 of the way out (on the screen) doesn't represent 75ft when scanning 100ft. You have to recognize that the 0-100ft scan distance starts where the water column ends and goes out to the edge.

In other words...divide only the part showing the bottom into 4 equal parts and that should represent the 25-50-75-100ft points.</td></tr></table>

I agree with You on this.

Your scale only goes from the bottom of the water column to the edge. So the bigger the water column the smaller the scale and detail you will get. So you should always have a small water column to keep your detail from being compressed.

So in the picture above 100 ft of bottom is compressed into 1/4 of the screen.

It kinda had me thinging hard on this earlier,
Thanks for the help
http://www.bassboatcentral.com/smileys/bows.gif
721 Pro XP


Modified by 721 Pro XP at 5:37 PM 12/29/2010

if you go to youtube and search humminbird you will have several videos and there is one the explains all the distance and what not.i also find plenty of helpful info on hb's facebook page. http://www.bassboatcentral.com/smileys/thumbsup2.gif

721, Great question.. Here are some images I got to help explain.

In simple terms, Si operates the exact same as sonar in terms of determining distance. If you draw a straight line from the ducer to the object that determines the distance.

http://i123.photobucket.com/albums/o...onar/greg3.jpg

If you really want to get technical here is some detail info.

http://i123.photobucket.com/albums/o...onar/greg2.jpg

Think of it this way and I believe this has already been stated. If you are in 100ft of water and your beams are out 100ft your entire screen will be dark blue showing no lake bottom (or very very little lake bottom) indicating depth of water. So if a object is at the very edge of your screen it is 100ft away but could be right under the boat vs 100ft off to the side. Confusing but that is how it works.

If you section out a screen with lines this is how distance/depth is determined from the CENTER LINE. Having said that the screen is suppressed some ie putting 100ft of data on a small 1197SI screen. In the grand scheme of things I have found the GPS to be pretty dang gone accurate using the cursor to mark waypoints off to the side but having said that you do need to realize that the cone of a sonar isn't exactly pin point either when you go to refind that waypoint because Sonar beam at 30ft of water is 30ft (in dual beam). So you can still be off 27ft and still see the object you just waypointed.. GPS is almost pinpoint on land/surface of water but when you add depth is when it gets muddled some. Thankfully the shallower the water the more accurate the GPS point will be and the deeper the less "pinpoint" accurate it will be because of the depth of water. While all this info is good to know, but I think we are over thinking here. The GPS does "almost" all of the work for us so we don't need to bring a calculator on the boat.

http://i123.photobucket.com/albums/o...onar/greg1.png

Thanks Mike,
I know this is all kinda trivial, I never run my water column that deep, and I use the cursor to mark and go look at objects closer.

Looking at the graph you have posted the little one with the vector lines. The way I understand it the range doesn't start until the graph shows bottom then goes out to the distance you have set.

On the picture you have I believe the distance to shore is correct, and the distance to the channel would also be correct but the 73 ft line would actually be 100 ft.

So without changing your range as you get deeper you are compressing the bottom view between the edge of the screen and bottom of the water column. This is shown on the understanding SI graph, where the distance between 1 and 4 on the bottom. as the water column gets deeper line one (the bottom ) pushes out towards the edge (line 4).

Going shallower on the same scale will spread out the bottom as the water column shrinks allowing more detail to be shown on the screen.

So on the screen you have the range selected + the water column.

Do you buy that.
Just board at work.

721 ProXP



Modified by 721 Pro XP at 7:06 AM 12/30/2010

721, I totally understand what you are saying about the 73 supposed to be 100ft but thats not the way it works.

Picture this in your head. Your sitting in 102ft of water. Make your SI range 100ft to each side. What will you see? You will see NO lake bottom on your screen, but your beams are out 100ft so 100ft can't start when the bottom shows up because there is no bottom in this instance..... The water column counts as distance even though it's not horizontal distance (off to the side), (it's vertical distance under the boat).

Mike, do you use Humviewer to look at recordings on a computer?

I totally understand what you are saying and also agree.

I was just going by this chart you threw up. From what the chart says line one and 4 are the same. Line 1 being from under the boat. Line 4 going out to the range set.


http://i150.photobucket.com/albums/s...stom/greg2.jpg

Heck with it I'm going fishing.

Thanks All
721 Pro XP

721, Look at the graph I put up and find #1 in both. You doctored the photo wrong. 1 represents the depth and 4 represents the range in both parts on that image.

Ahhh so I see that now!!

So by looking at that and line 2, if you are in X ft of water nothing X ft out to the side of the boat is going to show up. What looks like it on the bottom of the lake is actually the water depth out to the side of the boat.

Maybe I have it now. If not I give up!!!!!

721 Pro XP

You are correct. Dark blue is depth. You don't start going horizontally out until you see the bottom like you stated. Don't give up I am sure lots of people learned from this. It's good stuff to know :) http://www.bassboatcentral.com/smileys/thumbsup2.gif

Mike

That makes since, I have see creeks and other objects where they don't look like they would match up if you took out the water column and that would be the missing info.
So daves display where he take and folds the paper to push the water column together is some what wrong. He should have left the bottom out to form a triangle up to the boat.

If your again..... In 25 ft of water on 100 ft scale, you are missing 50 ft of bottom under the boat. 25 left and right.

I think I have it now!!!!!
Thanks Mike

721 ProXP

So... looking at Mike's third image, in 50 ft of water on a 100 ft range, you really only see 50 ft of bottom (side image) starting 50 ft away from the boat.

Did I get that right?

[quote=
If your again..... In 25 ft of water on 100 ft scale, you are missing 50 ft of bottom under the boat. 25 left and right.

I think I have it now!!!!!
Thanks Mike

721 ProXP [/quote]

Uhhh....No!!

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Bryanmc57 &raquo;</td></tr><tr><td class="quote">So... looking at Mike's third image, in 50 ft of water on a 100 ft range, you really only see 50 ft of bottom (side image) starting 50 ft away from the boat.

Did I get that right? </td></tr></table>

Uhh....No!!

This is one of my favorites I have taken.... You can see the school of spotted bass that I ran over feeding in and out of shad just to the right of my boat line. Point being that you see straight down below the boat and out to the side. The fish and shad are showing up in the water column because they were under the boat at the time.
http://i53.tinypic.com/2z6dw61.jpg

And, I borrowed this one from one of TMike's post. As you can see, he drove right over the top of this tree and it split it perfectly in half because it does show what is directly under the boat.
http://i52.tinypic.com/2vmzxo5.jpg

Now this is how I read it when I'm on the water just to get a better view of what is there...I've turned the original picture I posted on it's side. Which is how I look at it when I fish. Imagine that you are swimming underwater towards your boat path (the line in the middle of the water column). The line(path) is the top of the water(surface) and you can see that there is the drop in depth and anything on the bottom.
http://i52.tinypic.com/ehaedt.jpg

And filpped the otherway to see the other side (swimming underwater from the bank to the boat path).
http://i52.tinypic.com/2csdzyb.jpg

Hope this helps you a little better.... http://www.bassboatcentral.com/smileys/thumbsup2.gif

And here's another thing...I have an 898cSI unit. I don't know if all models have this capability or not. I would think so. This is a picture of an old roadbed I fish. When I first got the unit I went and took a picture to see it. And later looked at the picture and moved the cursor over to zoom in on a spot. Well, the cursor tells you how far away the spot is at the top banner. Here are both shots of it....the first the cursor is still at 0.0ft and the next is at 28.2ft. That should be able to help also. http://www.bassboatcentral.com/smileys/thumbsup2.gif
http://i53.tinypic.com/qoh829.jpg

http://i52.tinypic.com/14iptkx.jpg

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by db_db &raquo;</td></tr><tr><td class="quote">Hope this helps you a little better.... http://www.bassboatcentral.com/smileys/thumbsup2.gif </td></tr></table>

Nope not really.

So looking back at the understanding SI. It shows an object directly under the boat being out to both sides of the graph. It is the little grey box. Like the tree on Mike picture you posted.

So Back to the original cone of cunfussion. As to how an object dirctly under the boat will show up, as to an object that is out the depth of the water away from the boat which in the SI graph shows up further out to where the green fish does.

http://www.bassboatcentral.com/smileys/ohwell.gif http://www.bassboatcentral.com/smileys/ohwell.gif

721 ProXP

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by db_db &raquo;</td></tr><tr><td class="quote">
Uhh....No!!</td></tr></table>

Ok... If you look at the right side of Mike's third image, you can see he's in 27 ft of water on a 100 ft range. Lok at the second arrow, showing approx 73 ft from the edge of the water column to the rt edge of the image. 27 ft of water column + 73 ft of side image = 100 If what you contend is correct, then shouldn't his arrow say 100 ft from the edge of the water column to the end of the image? Or am I still thinking sideways?

Look at this video and the mud will go away on the tree question under the boat :)

http://www.youtube.com/user/im...PdMKc

Yea I have seen that before and that is why I have the questions.

So according to Doug's display If on a 100 ft scale in 75 ft of water you are going to be seeing the whole 100 ft range squeezed in to the last 25 % of the screen on each side. Being that what ever is under the boat showing at the bottom of the water column and an object being 100 ft away being on the outer edge.

My first image up would be correct and on the picture you put up the 73 ft line would be 100 ft thus squeezing the image into a smaller scale. As you go shallower the image would stretch out as the water column gets narrower and you have more room to show the 100 ft of info in.

On the screen you have the water column + the range on each half of the screen.

In 5 ft of water you are going to have 95% of the side of screen to show 100 ft of detail. In 90 ft of water you are going to have 10% of the screen to show the same amount of detail (100 Ft of bottom).

Is this what we are agreeing on????

As doug movie shows you squeze the water column together and what lays flat on the table is 100 ft left and right of the boat, on a 100 ft range, no matter how much water column is there. The deeper the water column the taller the paper. But you still have 100 ft left and right on the table???

http://www.bassboatcentral.com/smileys/praying.gif http://www.bassboatcentral.com/smileys/praying.gif

721 ProXP

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by 721 Pro XP &raquo;</td></tr><tr><td class="quote">Yea I have seen that before and that is why I have the questions.

So according to Doug's display If on a 100 ft scale in 75 ft of water you are going to be seeing the whole 100 ft range squeezed in to the last 25 % of the screen on each side. Being that what ever is under the boat showing at the bottom of the water column and an object being 100 ft away being on the outer edge.

My first image up would be correct and on the picture you put up the 73 ft line would be 100 ft thus squeezing the image into a smaller scale. As you go shallower the image would stretch out as the water column gets narrower and you have more room to show the 100 ft of info in.

On the screen you have the water column + the range on each half of the screen.

In 5 ft of water you are going to have 95% of the side of screen to show 100 ft of detail. In 90 ft of water you are going to have 10% of the screen to show the same amount of detail (100 Ft of bottom).

Is this what we are agreeing on????

As doug movie shows you squeze the water column together and what lays flat on the table is 100 ft left and right of the boat, on a 100 ft range, no matter how much water column is there. The deeper the water column the taller the paper. But you still have 100 ft left and right on the table???

http://www.bassboatcentral.com/smileys/praying.gif http://www.bassboatcentral.com/smileys/praying.gif

721 ProXP</td></tr></table>

Yes that is what I agree with you on. The 100ft is from the end of the water column to the outer edge of the screen. http://www.bassboatcentral.com/smileys/thumbsup2.gif
And yes the shallower the water the smaller the dark water column area is going to be. http://www.bassboatcentral.com/smileys/thumbsup2.gif

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by db_db &raquo;</td></tr><tr><td class="quote">

Yes that is what I agree with you on. The 100ft is from the end of the water column to the outer edge of the screen. http://www.bassboatcentral.com/smileys/thumbsup2.gif
</td></tr></table>

So then the notation on Mikes third image is incorrect?

Maybe this image will clarify all doubt. The cursor show 22.2ft and it's in the water column? If the range started at where the bottom starts the cursor would show 0ft until it got to where the bottom starts.

http://i123.photobucket.com/albums/o...nar/cursor.jpg

This isn't what was explained in comments above (I don't think http://www.bassboatcentral.com/smileys/doh.gif ).

In this image, there is no "blind spot". You are seeing the entire area below the boat in the water column as well as all the way out to the 134' setting both left and right.

Correct?

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by T Mike &raquo;</td></tr><tr><td class="quote">Maybe this image will clarify all doubt. The cursor show 22.2ft and it's in the water column? If the range started at where the bottom starts the cursor would show 0ft until it got to where the bottom starts. </td></tr></table>

So basically I'm right then? The "side image" (blue) portion shown = range minus water column depth? In this new image we're seeing the bottom from 134 ft to the side IN to 64 ft from the boat, correct?

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Bryanmc57 &raquo;</td></tr><tr><td class="quote">

So basically I'm right then? The "side image" (blue) portion shown = range minus water column depth? </td></tr></table>

As I understand it (if i understand what you mean by (blue). Range - depth = actual bottom coverage.. http://www.bassboatcentral.com/smileys/thumbsup2.gif

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by BrownTrout &raquo;</td></tr><tr><td class="quote">This isn't what was explained in comments above (I don't think http://www.bassboatcentral.com/smileys/doh.gif ).

In this image, there is no "blind spot". You are seeing the entire area below the boat in the water column as well as all the way out to the 134' setting both left and right.

Correct?

</td></tr></table>

My head is hurting too LOL. But what you said above is how I interpret it. The depth of the water counts towards the range.

Ding ding ding.......
I got it now!!!!!!!

The range is the length of the beam.

In 100 ft scale In 30 ft of water.
A fish suspended at 15 ft will show 15 ft.
The bottom will show 30 ft the length of the beam to the bottom.
An object under the boat will show the beam length to it, rgus 30 ft, an object 10 ft off the bottom will show 20 ft like the grass in your last shot. It's not 20 ft out to the right of the boat it 20 ft under the boat.
An object 10 ft to the right will show around 40 ft, not out to the side of the boat, but the distance at an angle of the beam down towards the object, ie 30 ft + 10 ft out to the object. An object 10 ft to the side of the boat will range further away showing 40 ft when it is only 10 ft from the boat.

Now if you are on 150 ft range in 120 ft of water, an object at 150 would really only be 25 ft or so from the boat.

So if your in 49 ft of water, on the 50 ft range 49 ft from the bank. The water column is going to be 49 ft, an object directly under the boat is going to be 49 ft away. This will show up at the bottom close to the edge, also an object just off the bank is going to show up there also basically on top of each other ie being 49 ft from the boat. An object half way down the bank in 25 ft of water would also show up there, on the beginning of the bottom, ie 49 ft from the bottom.
Now in this last one the object half way down the bank, its in 25 ft of water, and 25 ft from the boat yet will show 49 ft. The lenght of the beam from the transducer to the object.
http://www.bassboatcentral.com/smileys/newyear1.gif http://www.bassboatcentral.com/smileys/newyear1.gif http://www.bassboatcentral.com/smileys/newyear1.gif

I did this on my phone so forgive my typing and spelling

721 Pro XP


Modified by 721 Pro XP at 1:58 AM 1/1/2011

I'm glad you understand now because what you just wrote confused the crap out of me again (still) http://www.bassboatcentral.com/smileys/roll.gif http://www.bassboatcentral.com/smileys/roll.gif http://www.bassboatcentral.com/smileys/roll.gif