Posted by Anna's Dad on 09-20-2003 07:18 AM:

Fish Finders and Boat Control

I have a few elementary questions about using a fish finder. I have a portable Fish Mark 320, nicely packaged by Cabela's, that I use on rented boats. The Fish Mark seems to perform very well. My performance is a different matter.

As I understand it, the information on the right margin of the screen is what's under the boat now and everything else is behind me. So if I see a bottom hump on the screen, for example, I am already past it. I can turn the boat around and watch as I go over the structure again, but then, of course, I will be past it again. So, how do I position the boat over the hump (or a casting distance away) and hold it there long enough to fish? Is there a better tactic than just stopping the boat as soon as I see the hump and then casting over the stern of the boat? It seems like there must be.

To the extent that the Fish Mark is showing me fish, I have the same question plus how do I know whether the fish that I have gone over was holding or moving, or moved in response to the boat going over its head? Can I really use the unit to target a particular fish, or just to identify fishy water?

Thanks in advance.

Posted by mac on 09-20-2003 08:42 AM:

boat control

I have a finder in my kayak, and am aware of where the transducer is located....meaning, near the mid point of the yak, just under the seat. If I go over the hump and then return to it.....I can anchor when I see the bottom raising up to the top of the hump...just as it peaks.....I'm dropping the anchor from the mid point as well. In short, if you drop anchor....just make sure you are dropping it near the transducer....this will place you on that right edge of the screen. I then use a little spread to my casting.

In regards to targeting specific fish, I've read that some fellows in the river have success with large walleyes doing this, but I've never chased them down with my trolling motor like they have. Sounds like fun.... I think I've caught a few nice bass by casting backwards in the past after seeing a fish on the finder...whether it was the same fish or not, just really not sure.

Good fishing, Mac

p.s. Good post....good questions.

Posted by JOHN G on 09-20-2003 08:48 AM:

some good questions Dad.....

first of all: make sure the fishID is turned OFF!! this is very very important....you do not want the screen cluttered with little fishy pictures that are often inaccurate and just taking up valuable pixel information.....you do want it in Automatic bottom tracking mode, but turn OFF the fish ID....this way, you will not see a lot of arches, but when you do, they will more likely be fish....

the absolute most right handed part of the screen is recent, yes, however, the "history" is close or far depending on HOW FAST YOUR ARE MOVING with your boat.....if you are gently going along, and a stump is in the middle of the screen, you are not too far past it...

what a lot of people do, is go back and crisscross a spot to further narrow down where it is....sometimes, you can even use buoy markers at first, just develop a system where you don't drop the buoy right on the fish's head! LOL.....a hump can be very small or very large, just seeing an elevation for a second or two on the screen doesn't really qualify as a hump....you would have to see a sudden elevation that remains on the screen for a while followed by a sudden return to the original depth....this could take a while, in bigger waters, many humps are sunken islands and they could be a good 1/4 acre to an acre in size......

another thing to keep in mind is that the cone of the projected sound waves of the transducer is only a certain diameter, which increases as the water gets deeper....if you are going over water that is only 5 feet deep, you may only be seeing a foot or two diamter of coverage on the screen, whereas if the water is 30 feet, the diamter of coverage may be 7 or 8 feet...... any arch that you see in the immediate right hand portion of the screen is SOMEWHERE WITHIN THAT DIAMETER!!!! think about this, as you see a beautiful arch come up on the screen, that fish can be 3 or 4 feet to the right or left of you, not right under you.....

obviously, there is a little bit of experimentation involved here....if you are fishing vertically, that is why you have to drop your lure in several places, as it is not always a sure thing....also, as you noticed, it is NOT an easy thing to determine if the fish is stationary or if it is passing through the cone.....Pat X recently posted that he felt that if the arch was very pronounced it was stationary and if it was flattened out more like a straight line the fish was moving through the cone area.....

I would like to add more but have run out of time, I will come back on this thread.......

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Posted by Pete L on 09-20-2003 11:05 AM:

John - Sounds like you were paying attention at the NYBU !!!!!!!!

Good info !!!

Dad - John puts this to good practice --- especially with toothy critters!!

Pete

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"Life isn't like a box of chocolates...it's more like a jar of jalapenos.

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When everything is coming your way, you're in the wrong lane

Posted by BassMiesterNJ on 09-20-2003 01:37 PM:

John, nice info. I've never had it explained quite that way.

Fish finder and front trolling motor are both on my list for next season !

Posted by Anna's Dad on 09-21-2003 03:42 AM:

Thanks, John, for your thoughtful and very helpful response. I'm looking forward to anything you might add when you get time to come back to the thread.

Posted by Senkosam on 09-21-2003 09:03 AM:

Most fishfinders don't find fish, at least not the fish most shallow anglers can catch. By the time you've detected a fish in 7', it's gone or it's a carp or other bottom feeder. Fishfinders locate schools of bait fish in deep water as well as deep running species below them (bass, walleye, lake trout, stripper, etc.). I wasn't sure what depth you usually fish, so I'll go on to assume that your're talking under 10'.

Marker buoys are the best at defining the edges of structure. The key to marking structure is to throw out a marker buoy every 20-30 yards, marking the structure's length and breath. Triangulation with shoreline objects is okay for general structure location, but the irregularities of structure edges or content (stumps, boulders, hard/soft transitions) are impossible to keep track of and fish at the same time.

Your're right, once you've passed over something, it's history displayed on the LCD, including fish passing within the cone. The common cone angle of 17 degrees, displays only a few feet in 10' and far less in 5', so what you see is what you get. Fish, to the side of the cone, are not as critical as those found under a boat in 35-50'. (Certain units contain symbols to mark fish to the right and left of the cone edges as well as the depth their holding.)

The only finder that detects fish that you can catch in shallow water and on any the side of the boat, are sidefinders. Depending on the range set (10'-80'), the cone angle of 17 degrees still comes into play as far as area covered, but is of little importance since the fish found are within the top 5' or less of the surface. This means that if your're surveying a shoreline (or open water), parallel to a target area, any fish, no matter the size, will be displayed along with their numerical distance from the transducer. If the sidefinder transducer is mounted on the trolling motor, you have the ability to track fish within a complete circle, the area of which depends upon the range set, the direction dependent on swiveling the trolling motor.
Thus you can find fish in front of or to the back of the boat also.

For example, Wild Bill and I fished a local lake recently and he asked about the constant beeping of the finder. I was able to tell him the exact fish location, size and distances from the boat. We were surveying a shore with docks, flats and minor points. In fact, one dock of 3 docks, was shown to have a number of larger fish under or near it. Bill caught 3 nice bass off the same dock in less than 5 minutes! The other docks only showed minnow-symbols and no fish were caught there.

Yesterday I was surveying a large hump that always holds fish in spring and fall. The hump is within 4' of the surface but drops to 10' on it's sides. Once I found the edge, a dropped a buoy and scooted back out to deeper water. I know the general direction (NE) of the hump, so I traveled 30 yds, located another edge, and dropped a marker. I went to the other side of the hump (around it) and marked a third side and anchored. The sidefinder, (which also always marks the depth under the boat in case you drag anchor off the area), helped me locate fish schools in a specific direction on the hump and feeding schools to the sides of the hump over deeper water. It turned out that bass and crappie were chasing fingerlings in three separate schools and I was able to catch both species for over an hour, anchored in one spot. As long as the sidefinder showed shallow feeders (relative to the surface), I held position and didn't miss the moving schools by moving the boat.

I also surveyed a small group of very shallow pads known to hold fish. The sidefinder indicated panfish and larger fish, mixed. I took three bass and a pickerel in the same area that only had a depth of 3' or less, close to shore. Other pads and docks showed no fish, and after confirming with a few casts, kept on parallel to shore - 30 yds out, over 6' of water.

The sidefinder is just as accurate and time saving in shallow creeks and small rivers. Last year I canoed the Wallkill R. and was going downstream to end the trip. The sidefinder found fish migrating in the opposite direction. (I stopped the canoe and turned the transducer up stream and noted the increasing distance of the fish.) I followed, cast and caught 5 smallies I would have missed. The stretch was in less than 4', 1/4 mile long and 70 yds wide, but I was able to detect a school that caused an audible alarm and allowed me to take action.

If you generally fish deep structure (especially vertically), a general-usage-sonar is valuable for depth and bottom compositon changes. (I won't waste time fishing for smallies over muddy bottom.) If you're a shallow water angler, you can know the depth the boat is over, but not any information regarding the shallow water your're casting to. In a highlands lake such as Swinging Bridge, rock walls in 20 feet are key to success on some days. Markers help, but shutting the sonar off is sensible since it's no longer needed to find that, which holds fish.

FrankM

Posted by JOHN G on 09-23-2003 02:18 PM:

will get to see Franks sidefinder prowess live at one point on Orange Lake.......

more on the sonars: I mentioned keeping the fish ID off, thus preserving pixels...

this is a common theme that pops up with these units, as you have a fixed number of pixels and the more pixels, the higher the resolution and accuracy....obviously then, the same number of pixels in 60 feet of water will give less detail than in 20 feet of water....

a good way to maximize pixel use in deeper water is to use the Zoom function......if you limit the screen to only the bottom 10 feet of water or less, then you will get much finer resolution of what you see on the bottom, distinguishing a fish next to a stump, for example.....

whenever you are searching the bottom, and you are in 15 to 20 feet of water, at least hit 2X zoom, whereas in 30 feet of water or more, you can hit 4X zoom....

again, this is when you feel that active agressive feeding fish will be on the bottom......zooming at 4X will not show you fish suspended in the water column, but will give you stunning detail of anything near the bottom.

another pixel maximizing trick when searching for suspended fish is to manually set the range, instead of using the bottom tracking feature......now you can set it to show only the first 20 feet of water, say, from the top to the bottom.....once you have that, you can even zoom that for more detail......if you have an idea of what depth the fish suspend, think about it, if you are searching for suspended smallies, 25 feet down over 50 or more feet of water, better to manually set the range, perhaps to 30 feet, so that all of the pixel count will be used where you want it , in the suspended range....you will also see suspended balls of baitfish much better using that method.....

unfortunately, I am assuming that your depth finder has these features, which in this case, Dad's 320 DOES....

another reason to not go cheap when purchasing your first fishfinder....to not be able to do all of the things I mentioned would be a shame.....

now when you get these unbelievable 320 by 320 pixel displays, and then adjust them so that they are only showing a small amount of water, you are getting a real fine pitch of resolution.......

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Posted by MikeM on 09-23-2003 03:23 PM:

John G,
Great post buddy .....I think you should change your prefix from Dr. to Professor !
MikeM

Posted by Zuke on 09-24-2003 10:11 AM:

Perhaps the most informative thread...

I want to express sincere gratitude. I have often wondered how many people out there were like I have been....I have a beautiful Lowrance X71 on my rig, but have always felt as if I was VASTLY underutilizing it, or simply using it incorrectly. This thread has really opened my eyes. Thanks for the practical tips.

Often I am fishing in 5-10 feet of very weedy water. I don't use the finder that much in that situation because I've felt that all I was going to see was muck. Moreover, I've bothered so little with "hump" finding and fishing, mostly because it's difficult to determine beginnings and ends. I won't make that mistake again. I never realized how much effort serious fisherman put into contouring the structure, marking it, and anchoring on it. I will definitely try because it seems that the payoff would be worth it.

Let me add another question that may already be addressed above: when using the finder to look at bottom contour, are you looking at all for fish to target, or baitfish clumps, or other? Additionally, I have often passed baitfish clumps suspended in deep water and never bothered much with them because I always figured that they were transitory/moving....Do baitfish clumps tend to stay put enough for us to fish beneath them, etc?

Thanks for the great thread, and any advice.

Zuke

Posted by Woody on 09-24-2003 10:42 AM:

Zuke

"Additionally, I have often passed baitfish clumps suspended in deep water and never bothered much with them because I always figured that they were transitory/moving....Do baitfish clumps tend to stay put enough for us to fish beneath them, etc"

Any time I pass over a baitfish hump I want to throw something that falls through the clump of baitfish.
Depending on the quality of your machine...More often than not you will mark images of fish under the pod.
Theses are the fish you are seeking !!!!

If you see baitfish busting on the surface...Samething...Throw ASAP.

Tight Lines,
Woody

Posted by JOHN G on 09-24-2003 09:24 PM:

Woody is correct....Zuke: Pat X has perfected chasing those baitfish clumps out in the deep water at Mahopac and has pulled giant smallies into the boat doing so.....

I would have to say that in a predominantly smallie water, like say, Candlewood, that could be an indicator of active fish to find....myself, I try to blade bait into those clusters and below them when fishing deep water......

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Posted by got_A_way on 09-25-2003 01:53 PM:

Any sideview recommendations

I have the Eagle 320, and have taken John G.'s advice to heart.

What is a good sideview unit? Can I just turn my 320 transducer sideways ?

Great thread !

Fish Hard
Bob

Posted by JOHN G on 09-25-2003 09:01 PM:

Bob: you should have seen how that 320 performed on both Zoar and Swinging Bridges, being that I had never fished them before.....I was getting such a clear and detailed picture of the bottom of that lake, it was just amazing......

I am so glad you got that unit, the way I was pushing them on people you would think that I was a sponsor or something but of course, I sponsor nothing, just felt more strongly than I ever had for a piece of equipment that as I have said is the steal of the century right now for what it offers.....

I too have wondered what would happen if you simply aimed the transducer sideways?? it is designed to bounce off of things and then return the signals to the unit.....now: it is always expecting a bottom to hit....that is how those units are designed...if the sound waves just keep going out with nothing to hit but perhaps fish, I don't know if it would interpret that correctly.....

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Posted by Anna's Dad on 09-26-2003 05:57 AM:

I have not had a chance to check this thread for a few days, but I am grateful for all the thoughtful responses. Its been very hard to find information on how actually to fish with a depth finder, but the folks on this site have come through again. Many thanks.