Returning to structure once found on electronics

[Scherbacj]

What strategy do you use to return to/fish spots you find on your down/side imaging? I recently Upgraded to a boat worthy of a fish finder and while I idle/troll along and identify spots I want to fish, I drop a waypoint, but even with the waypoint and the graph saying I’m in the same spot, I don’t see the same structure/targets. I try searching around that area and can’t seem to locate the same brush pile/tree I just saw. I have a Lowrance HDS Pro and I can select the actual target on the screen when creating the waypoint so I don’t think I’m “seeing” it on screen but creating the waypoint too late. I know the tranducer is at the rear of the boat, but even just trying to pass over the area again to confirm where it is won’t work. I have even had my Ghost autopilot to said waypoint and don’t see the same targets I did before. Am I just stupid? How do get back to targets you find while idling? 

[WRB]

Back in the day when we only had flashers and marker buoys we learned the actual structural element was behind the boat where the transducer has pasted over it.

We tossed a marker buoy behind the boat to mark the spot. Flasher were actually faster displaying the structure because no delay displaying it.

When you see the structure element it’s at least a boat length behind you. Turn the boat around and make a second way point the true location is between the 2 way points of structure or fish.

Tom

[Craig P]

I was like you before I had a heading sensor…which is why I bought a heading sensor so you’re not alone in the confusion.

 

My best suggestion is to find and mark a structure you are familiar with that also has a visual shore line reference. Once you get familiar with that mark (feeling it out with a football jig helps a lot!) you’ll gain some insight with your boat position on future marks.

[Scherbacj]

2 hours ago, WRB said:

Back in the day when we only had flashers and marker buoys we learned the actual structural element was behind the boat where the transducer has pasted over it.

We tossed a marker buoy behind the boat to mark the spot. Flasher were actually faster displaying the structure because no delay displaying it.

When you see the structure element it’s at least a boat length behind you. Turn the boat around and make a second way point the true location is between the 2 way points of structure or fish.

Tom

that makes sense, but I can actually put a marker on the target on the screen and create the waypoint at that marker, so even if that spot is behind me and is about to fall off the screen, if I select that point, shouldn’t the waypoint be at that marker and not the current position of the boat? If it is still using the position of the boat when I click save then it doesn’t make sense why you would be able to select the target on the screen and say “create waypoint”. Especially because even after saving the waypoint, the screen still shows the frozen frame of the target and the name of the waypoint until you click to return to the sonar screen. Also, I would love to make a second waypoint and then know my target is in between the two, but I can’t even find the target a second time in order to make the waypoint. It seems like I am going far enough past the waypoint so even if it was a boat length behind me that I should still

pass it again, but I’m not seeing it. 
 

I think I will just throw out a marker buoy and then probe it with a bottom contact bait until I get a feel for where the waypoint is in relation to the boat. It just doesn’t make sense to me that I can select the target if that isn’t where the waypoint is actually placed. 

[Team9nine]

When trying to return to the new waypoint, idle directly by where the icon on your screen is using your side imaging. If you didn’t go right over it, it will show you just how far off to one side and what direction it actually is. There is a calculation offset due to depth and distance from the transducer that frequently results in a position error when placing the icon on your screen.

 

Another option would be to drop a marker buoy on a known underwater object, then idle back by it using your SI from some distance off and try placing a waypoint on the screen and see just how far off from your buoy you end up when returning to the icon/waypoint you just added.

[A-Jay]

Returning to structure once found on electronics ~

@Scherbacj

I fished for several years using a very similar process as you mentioned above.

Sometimes It worked out.

Often it was an exercise in futility,

especially on big bodies of water, marking fairly small targets and in less than ideal conditions.

I've all but abandoned that methodology.

So instead of dropping a way point directly on anything I want to fish,

I put ALL my waypoints where the boat needs to be located to fish that particular deal effectively.

A couple of points of interest;

It keeps me off the fish,

I may have to mark a coupe of spots at each 'end' of a target, to account for wind, waves or current.

As for 'initially finding' them and re-locating them.

Once I go over or by them I'll put my pin right there just for reference.

I might leave it and fish there or I might discover a better location

and erase that one and use the new one.

Really helped clean up my units of what I can only designate as BS way points.

This is a work in progress as last season I erased nearly 1,000 way points collected over several years

on several lakes, that were admittedly a Helter Skelter collection of only half usable deals.

So I started from scratch using the above method. 

Has worked out well so far and the mantra is "Trust the Way Point.

Good Luck

A-Jay

 

[WRB]

What you all are missing is the way point is where the boat was but the structure element is behind the boat when you mark the boats position.

Ifyou put down the TM and find the structure then mark your way point while on top of the structure or fish.

Tom

[A-Jay]

9 minutes ago, WRB said:

What you all are missing is the way point is where the boat was but the structure element is behind the boat when you mark the boats position.

Tom

Nope,

I get it.

A-Jay

[casts_by_fly]

11 hours ago, Scherbacj said:

that makes sense, but I can actually put a marker on the target on the screen and create the waypoint at that marker, so even if that spot is behind me and is about to fall off the screen, if I select that point, shouldn’t the waypoint be at that marker and not the current position of the boat? If it is still using the position of the boat when I click save then it doesn’t make sense why you would be able to select the target on the screen and say “create waypoint”. Especially because even after saving the waypoint, the screen still shows the frozen frame of the target and the name of the waypoint until you click to return to the sonar screen. Also, I would love to make a second waypoint and then know my target is in between the two, but I can’t even find the target a second time in order to make the waypoint. It seems like I am going far enough past the waypoint so even if it was a boat length behind me that I should still

pass it again, but I’m not seeing it. 

 

You are correct in how it works.  You need to factor in the distance between the head unit (gps source) and the transducer.  if you're sitting in the console of a 20' boat and the transducer is on the stern then you're going to be off by about 10'.  Do additional passes per below if you need a higher level of accuracy, but I don't think that's what you're talking about here.  It sounds like you're just not finding it at all.

 

7 hours ago, Team9nine said:

When trying to return to the new waypoint, idle directly by where the icon on your screen is using your side imaging. If you didn’t go right over it, it will show you just how far off to one side and what direction it actually is. There is a calculation offset due to depth and distance from the transducer that frequently results in a position error when placing the icon on your screen.

 

@Scherbacj- take note of the offsets and errors.  while you can drop a waypoint on a brushpile (for instance) and you're usually pretty close, criss crossing your original path at 90 degrees and off to the side of it (while using side imaging) may yield a slightly different waypoint.  If it's an important thing you want to be very precise on later then take 2-3 passes and mark it as 3 waypoints.  

 

Also note that depending what you're marking, you will get a different return from different angles.  In the most extreme case, picture a billboard on the bottom (like a roadside billboard).  Drive parallel to it and you've got the entire face of the billboard to reflect against.  Drive perpendicular and you get the very skinny side.  Totally different looking images on the screen, hence a second pass at 90 degrees.

 

[WRB]

I will give this 1 more try.

Driving your boat at slow speed and your sonar screen displays the hypothetical billboard what you see displayed is in your rear view mirror behind you when you mark a way point.

Tom 

[Tennessee Boy]

Every modern fish finder that I've used records the GPS position when it pings with the data returned from the ping.  If you mark something in the sonar history it uses that recorded position and does the math on side imaging to estimate the distance out from the boat.  As @casts_by_fly noted,  the position is where the GPS is located which is usually the console and the ping happens at the transducer which can be a few feet away.  There is also the error that @Team9nine referred to that can be significant with side imaging.  You also have GPS position error which can be up to 16 feet but is usually within 5 feet.  All this can add up and can be a challenge if you are marking something small like a brush pile.   The modern solution is to use the waypoint to get close and use 360 imaging or FFS to find the exact location of the object after you drop the trolling motor.  All it takes is more money.  😁

[TnRiver46]

I Line it up with a tall tree or somebody’s roof 😂 

[casts_by_fly]

24 minutes ago, Tennessee Boy said:

Every modern fish finder that I've used records the GPS position when it pings with the data returned from the ping.  If you mark something in the sonar history it uses that recorded position and does the math on side imaging to estimate the distance out from the boat.  As @casts_by_fly noted,  the position is where the GPS is located which is usually the console and the ping happens at the transducer which can be a few feet away.  There is also the error that @Team9nine referred to that can be significant with side imaging.  You also have GPS position error which can be up to 16 feet but is usually within 5 feet.  All this can add up and can be a challenge if you are marking something small like a brush pile.   The modern solution is to use the waypoint to get close and use 360 imaging or FFS to find the exact location of the object after you drop the trolling motor.  All it takes is more money.  😁

 

 

I also am fairly sure that in a lot of that have a creek channel and that flood in the spring that the brushpiles move.  Rocks not so much, but brushpiles do.  Whole trees do.  Three summers ago one of our reservoirs was fishing great.  There was a particular tree in 20' of water that came up to about 13' under the surface and was the only cover around on a good rocky point that had a deep edge on one side and a flat edge on the other.  It was good for a couple.  The following summer the lake level dropped steadily and the fish still related to it even when it was breaking the surface.  The lake filled that spring and I haven't seen that tree since.  I imagine gravity did its thing when the water level dropped to zero feet at the tree, either it rolled or broke.  Then when it filled the whole thing just drifted away.  It was on the main creek channel after all.  I miss that tree.

 

rick

 

[Hoosierman]

Sooooo...is the GPS sensor in the head unit / screen or the transducer?

If its in the head unit then GPS is ahead of the rear mounted transducer reading.

Sounds like this is what WRB is trying to convey. 

[WRB]

That isn’t what I am saying.

Flashers used horizontal lines to display sonar signal returns. Your digital sonar screen displays a history of the same sonar returns interpreted by the processor. The key word is “history” the only real time sonar returns are displayed on a narrow vertical bar (flasher) located on the far right side of the sonar display before being processed.

Your boat is moving forward the sonar signals sent out and returned by the transducer. Because your boat is moving forward everything within the transducer signal has been passed by it’s in your wake behind you. By the time you see the signal displayed and react to what you see the boat is traveling further away behind the boats transducer.

You mark the spot where the GPS is currently located but the structure element or fish is further back in your wake depending how fast the boat is moving.

Tom

[casts_by_fly]

2 hours ago, Hoosierman said:

Sooooo...is the GPS sensor in the head unit / screen or the transducer?

If its in the head unit then GPS is ahead of the rear mounted transducer reading.

Sounds like this is what WRB is trying to convey. 

head unit. It can get complicated if you have a trolling motor with both a gps and transducer as well as a console and bow mounted unit. Minn Kota has a guide as to which “thing’s” data is used in what scenario (spot lock, waypoint marking, navigating to a waypoint, etc).

 

 

1 hour ago, WRB said:

That isn’t what I am saying.

Flashers used horizontal lines to display sonar signal returns. Your digital sonar screen displays a history of the same sonar returns interpreted by the processor. The key word is “history” the only real time sonar returns are displayed on a narrow vertical bar (flasher) located on the far right side of the sonar display before being processed.

Your boat is moving forward the sonar signals sent out and returned by the transducer. Because your boat is moving forward everything within the transducer signal has been passed by it’s in your wake behind you. By the time you see the signal displayed and react to what you see the boat is traveling further away behind the boats transducer.

You mark the spot where the GPS is currently located but the structure element or fish is further back in your wake depending how fast the boat is moving.

Tom

 

Tom,

 

You are correct that what you see on the screen is the scrolling history and things on the left of the screen can be a hundred feet behind you depending on your boat speed and scroll speed.  However, on the OP’s unit and mine you mark the point on the screen anywhere in the history, not the current scrolling position. If you have a brush pile halfway across the screen (let’s say that’s an actual 50’ behind where you were when you scanned it) you scroll the cursor across the screen to the pile (or just touch it with some units) and the head unit converts that screen position to a set of gps coordinates. The coordinates are ‘exactly’ where the head unit was when the pile was scanned. I quote ‘exactly’ relative to the caveats stated above.

[Scherbacj]

1 hour ago, WRB said:

That isn’t what I am saying.

Flashers used horizontal lines to display sonar signal returns. Your digital sonar screen displays a history of the same sonar returns interpreted by the processor. The key word is “history” the only real time sonar returns are displayed on a narrow vertical bar (flasher) located on the far right side of the sonar display before being processed.

Your boat is moving forward the sonar signals sent out and returned by the transducer. Because your boat is moving forward everything within the transducer signal has been passed by it’s in your wake behind you. By the time you see the signal displayed and react to what you see the boat is traveling further away behind the boats transducer.

You mark the spot where the GPS is currently located but the structure element or fish is further back in your wake depending how fast the boat is moving.

Tom

I understand that in concept, but when you select a target on the screen you are selecting a part of that history, when I hit “create waypoint” shouldn’t the waypoint be placed where the cursor is in that history? If that is the case, it shouldn’t matter how fast I was going, or how far away I was when I created the waypoint. 
 

If it is creating the waypoint at my current location instead of at the cursor then I can understand the offset, but I don’t see why you would be able to select a point with the cursor and then create a waypoint if it isn’t making the waypoint at that location anyways. 
 

so I guess my question is, which way is it? When I have a target on the screen, I select it with the cursor and create a waypoint, is the waypoint being created at the cursor location? Or is it still creating it at the current location of the boat/head unit? 

[gim]

Something that has yet to be mentioned here, how fast is the OP going when side scanning?  I have a Lowrance unit and the manual states that 5.0 mph is ideal for maximum efficiency with that feature.

[WRB]

16 minutes ago, Scherbacj said:

I understand that in concept, but when you select a target on the screen you are selecting a part of that history, when I hit “create waypoint” shouldn’t the waypoint be placed where the cursor is in that history? If that is the case, it shouldn’t matter how fast I was going, or how far away I was when I created the waypoint. 
 

If it is creating the waypoint at my current location instead of at the cursor then I can understand the offset, but I don’t see why you would be able to select a point with the cursor and then create a waypoint if it isn’t making the waypoint at that location anyways. 
 

so I guess my question is, which way is it? When I have a target on the screen, I select it with the cursor and create a waypoint, is the waypoint being created at the cursor location? Or is it still creating it at the current location of the boat/head unit? 

The topic is returning to a way point.

Relying on GPS map way point is only as accurate as the map data. Selecting a map way point is independent of metering a way point with sonar.

You can select a map way point with a cursor you marking a longitude / Latitude numbers independent of your actual location.

Tom

[Scherbacj]

1 minute ago, WRB said:

The topic is returning to a way point.

Relying on GPS map way point is only as accurate as the map data. Selecting a map way point is independent of metering a way point with sonar.

You can select a map way point from your home.

Tom

I am talking about dropping a waypoint of something that I just scanned with my transducer, not something I marked from home. Obviously if I am marking a location from my home I am not expecting it be exact because at that point, it’s like you said, it’s general map data, not sonar data. When I create waypoints from home I am only selecting general areas, points, flats, etc. not a specific piece of structure.
 

What I am talking about is idling over a target, scanning it with the transducer, seeing a piece of structure in the sonar data, selecting it, dropping a waypoint so I can return to it and fish it that same day, but once I turn around and try to pass over it again and fish it, I am not finding the target. Even when trying to turn around, pass over it again and rescan it, confirm its location and get a better look at it, even though it shows I am passing over that waypoint just going the other direction, I have trouble finding that target again. I have done the things others have suggested like going at it from a different angle, trying to pass over it again and create a second waypoint to make it more accurate, etc. but I am rarely able to find that target again even when I drive to it and then beyond the waypoint I just made. I will say most of the time I am doing this it is with down imaging because I know that Side Imaging offsets are greater. Maybe next time I will find the target with down imaging but when returning to it I will pay more attention to the side imaging so that even if I am off by a few feet I should still see it in the side imaging and what side of the boat it’s on. 
 

So my questions remains, with a Lowrance HDS Pro unit, if I select a target on the screen and create a waypoint, it creates the waypoint at the target and not the current location of the boat/head unit, correct? 

[VolFan]

I use at least one tree and a rock. Evergreens are easier in winter. Must be a Tennessee thing.

[Scherbacj]

21 minutes ago, gimruis said:

Something that has yet to be mentioned here, how fast is the OP going when side scanning?  I have a Lowrance unit and the manual states that 5.0 mph is ideal for maximum efficiency with that feature.

Correct, I am keeping it under 5mph based on the manual. Most times I am idling as slow as I can which is usually around 3-3.5MPH. But, as I said before, if I am selecting the target from the history and just hitting create waypoint at my location, speed really shouldn’t matter. I will take a screenshot next time I do it, but I am pretty sure that when I select the target it shows Lat/Long Numbers as well as depth data for where the cursor is, which is why I assumed that is where the waypoint is being placed, not at the current location of the head unit. 
 

Even if it was creating it at the current location of the head unit, I wouldn’t think it would be a football field behind me if the target is still on the screen and I am only going 3mph. I have tried driving past the waypoint a fair amount and even then I don’t always find the target again. 
 

Maybe I am just stupid and not understanding this, but if the waypoint is placed where I have selected it in the sonar history, the waypoint should be at the target, not the boat. 

4 minutes ago, VolFan said:

I use at least one tree and a rock. Evergreens are easier in winter. Must be a Tennessee thing.

I would love to, but I live in AZ, a lot of times there aren’t specific trees or rocks on shore that I can try to line up with. Also, I am talking about targets that off shore, so a tree/brush pile on top of a hump in the middle of the creek channel, the bank might be far away so using a target on the bank to line up with isn’t always an option. 

[Tennessee Boy]

39 minutes ago, Scherbacj said:

Maybe I am just stupid and not understanding this, but if the waypoint is placed where I have selected it in the sonar history, the waypoint should be at the target, not the boat.

You are correct.  The waypoint’s coordinates will be the GPS position when the ping was made from the transducer for the data you mark in the sonar history.  I have done this countless times.

[Team9nine]

5 minutes ago, Scherbacj said:

Maybe I am just stupid and not understanding this, but if the waypoint is placed where I have selected it in the sonar history, the waypoint should be at the target, not the boat. 

Correct - but I don’t have your unit. I’d have to believe it works just like you’re thinking. I did it all the time with Garmin and Humminbird units. The first mark usually isn’t perfect, but close enough that you can refind it and mark it more definitively easy enough. 

[WRB]

49 minutes ago, Scherbacj said:

I am talking about dropping a waypoint of something that I just scanned with my transducer, not something I marked from home. Obviously if I am marking a location from my home I am not expecting it be exact because at that point, it’s like you said, it’s general map data, not sonar data. When I create waypoints from home I am only selecting general areas, points, flats, etc. not a specific piece of structure.
 

What I am talking about is idling over a target, scanning it with the transducer, seeing a piece of structure in the sonar data, selecting it, dropping a waypoint so I can return to it and fish it that same day, but once I turn around and try to pass over it again and fish it, I am not finding the target. Even when trying to turn around, pass over it again and rescan it, confirm its location and get a better look at it, even though it shows I am passing over that waypoint just going the other direction, I have trouble finding that target again. I have done the things others have suggested like going at it from a different angle, trying to pass over it again and create a second waypoint to make it more accurate, etc. but I am rarely able to find that target again even when I drive to it and then beyond the waypoint I just made. I will say most of the time I am doing this it is with down imaging because I know that Side Imaging offsets are greater. Maybe next time I will find the target with down imaging but when returning to it I will pay more attention to the side imaging so that even if I am off by a few feet I should still see it in the side imaging and what side of the boat it’s on. 
 

So my questions remains, with a Lowrance HDS Pro unit, if I select a target on the screen and create a waypoint, it creates the waypoint at the target and not the current location of the boat/head unit, correct? 

Correct you can do that multiple times around the lake and return to those exact long/lat numbers you made way points.

Be careful you create trails so you don’t try to return in a straight line.

Tom