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Wish-I-Were-Fishn

GPS vs floating markers

23 posts in this topic

OK so I've got this great GPS (Lowrance H2Oc & Lakemaster chip), but at only works above a certain speed. That's ok for finding structure locations, but once there and when I slow down to fish, it no longer works. Do you guys use markers combined with the GPS, or how do you work it? I was hoping that I could just follow the contours on my GPS with Lakemaster chip, but between the speed issue and also the inaccuracy of the GPS, it is not working out that way. I know markers can be a real boat magnet, but I don't know what else to do.

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Good question, It'll be interesting to see the different answers you get. What do you mean your GPS doesn't work at slow speeds? I have a Garmin Etrex Legend and absolutely love it, I use it instead of a marker 98% of the time. I love being able to zoom in and see the "hot spots" I've marked without having the visibility factor for others to see. The GPS does it for me.

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If I'm trolling with the main or kicker and it's not too tight (or I know the run very well) then I just use the GPS. If I'm using the Minnkota and casting, or the structure is real tight then I like to set out markers and key off them.

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I have the same unit with the Navionics chip and that is all I use, trolling, drifting, doesn't matter I can stay on the structure with no problems. I also would like to know what you mean by the GPS doesn't work at lower speeds.

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I use a marker... I have a nice GPS, but I cant seem to get within 4 or 5 feet of my structures... The GPS claimed to be accurate within 3 feet though, but that was a lie. At least from my experience it is. A marker will let me get exactly on the structure.

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My GPS (GPS76CSX) had the electronic compass.. so it works even while motionless.. and if I set 'track up' regardless of my position it stays oriented properly.. works great! But the downside is GPS's aren't nearly as accurate as a marker! And update 1/sec so the screen gets a bit choppy.. and of course you need it fairly horizontal for the electronic compass to work right.

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Thats asking a lot to have a GPS device accurate to 3 feet consistently.

I use the small film containers for markers works great only you can see them they definitly attract less people to the area I'm fishing which is nice.

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Take a marker and paint it black or dark green if you are worried about other boats seeing your marker. I have gps but I will still always throw out markers when I am fishing deep structure. I definetly like to have the visualization of the marker, it really helps you get your bait in the exact spot you want, where a gps cannot always do that.

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Actually I believe it states accurate to 3 meters which is bout 9 feet.US military controls civilan GPS and fears if there too accurate,bad things could happen.so today off 3 meters to the east tomorrow off 3 meters to the west,6 meters diff.18 ft. not pin point but fine with me out on a big lake,I'll put a marker out.It gets me to a very close point.

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One nice feature of the new Lowrance expedition is the electronic compas that will give you an accurate direction bearing while standing still. If you go to the nav screen you can get an accuracy measurement, which is usually about 18 feet on my GPS when I get a good WASS correction. I can't really complain about being off by a boat length. It also helps to zoom in close. Once you have your spot dialed in, if you don't use the Navionics chip you will be able to zoom in much further and get closer to your icon (but you will lose your depth contours on the gps). I'll take 18ft accuracy over extra boat traffic on an active school of fish anyday. Sometimes I keep an extra marker handy as a diversion, or for regular use on a low traffic lake on a weekday.

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Only very rarely will I use a marker and if I do its a black one.Between the gps zoomed all the way in,the depth finder and a compass I can generally stay pretty dang close where I want to be.

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I have a hard time understanding what you mean about "not working at slow speeds." That's one of the features I have found that surprises me about my GPS. I use a Garmin Rino120 handheld loaded with the Minnesota Lakemaster software and I have found the accuracy of the lake contours to be uncanny, especially on those lakes that are contoured to within 3' accuracy.

One must remember that the lake level can vary considerably throughout the year plus if you don't have an offset calibration feature on your sonar adjusted to compensate for the position of your transducer, the sonar depth displayed may vary a little from the depth noted on the GPS. The GPS doesn't measure the depth it only shows the contour that was recorded when the mapping software was generated.

My GPS with WAAS enabled quite often provides me a position accuracy to less than 9'. How much more accurate do you need to be?

One of the beauties of the GPS is that I no longer have to put out floating markers that attract the attention of other fisherpeople. It's amazing how often I have had markers out in the past and someone makes it a point to stroll by to check out what I have marked. With the GPS they know not what you are working.

Bob

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Yes, in addition to the GPS, I use my locator to pin point the structure. And yes, the depth is slightly different than the chip says, which makes sense. The issue is that the GPS doesn't track movement unless it's around 3 mph, which is to fast for presenting the bait in many situations. Page 7 of the manual says "in order for the iFinder to determine direction of travel, you must be moving and the faster, the better. This is not to say that it won't work at walking or trolling speeds - it will. There will be more "wandering" of the data shown on the display."

My experience with the unit says the required speed is much faster than "walking" speed. I think I will try walking around with it to see if I can get it to work. Maybe it was a bad day??

The unit is a Lowrance H2Oc, but I also have a Garmin 76s that has the same issue. I use the WAAS setting also.

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We use our H20 all the time walking. It tracks just fine at slow walking speeds. You may have to zoom in all the way to get the best effect. You may even zoom in to the point that the contours are not visible on the screen until you are right on it. Hope this helps. grin.gif

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Although GPS accuracy is greatly improved, many believe they can drop a smart bomb down a toilet stack like the miliary. Not so! Positional error ( the variance that occurs depending upon how many satelites you have a fix on and the strength of those fixs ) can be 9 feet or 60 yards and more. Trying to use your GPS and map card to pinpoint and stay on a spot like a marker is a long shot at best. Best bet is to use it to locate the structure then search with your depthfinder to find the structure and fish. When you do, drop a marker or two and fish.

Additionally, due to he ever changing positional error issue, those who place blind faith in zoomed in plot trails to safely navigate are asking for trouble too. When I first got my LMS 480, I was trying to beat a storm coming in and was exactly back tracking and following a zoomed in plot trail ( going out I was never in water shallower than 20 feet deep) back in. Clipped an unmarked rock pile at 25 mph and my skeg ended up looking like Grandmas teeth. Coulda been alot worse. Lesson learned. Be careful!

Stizo

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stizo I've an older Magellan,Merridian WASS enabled had it for years its never been off target by more than 30-40 feet most times its off only 10-20 ft.60 yds.?? I use it all over the state and Colo. Tx. confused.gif

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Quote:

Here is another source:

Outdoors » Outdoor Issues

A Global Positioning Satellite can't detect everything.

Submitted by jfischer on May 18, 2007 - 10:23am.

Filed under: Outdoor Issues

Boat hits island, fisherman severely injured

A Global Positioning Satellite can't detect everything, a boater in St. Louis County found out Thursday night.

Last update: May 18, 2007 – 8:51 AM

A Global Positioning Satellite can't detect everything, a boater in St. Louis County found out Thursday night.

Joseph F. Batkiewicz was returning to his campsite around 11 p.m. after fishing on Namakan Lake on the Canadian border in St. Louis County, Minn. He was using his GPS, but the device did not locate a small un-named island. Batkiewicz found the island when he ran his boat into it.

Batkiewicz, 41, of Monticello, suffered severe facial injuries from hitting the windshield, the St. Louis County Sheriff said.

Witnesses directed the Crane Lake First Responders to the scene.

The responders transported Batkiewicz by boat to shore where an ambulance took him to Cook, Minn. Hospital. He was later airlifted to St. Mary's Hospital in Duluth.

Batkiewicz was in good condition Friday morning, a hospital spokesman said.

Two other occupants of the boat were not injured, the St. Louis County Sheriff said.

The accident is under investigation.

The Accident on Namakan is a textbook reason why we should not completely rely on the little technology devices on the local lakes. This is an area with changing lake lavels, rocks, islands, and reefs. GPS units are getting cheaper and cheaper, combine that with people who are unfamiliar with the lakes and that is a dangerous combination in remote areas. Mix in other distractions and then you have some beg rescue efforts needed for very remote areas.


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You are correct about backtracking error. For example, if your GPS recorded the track with a 10' accuracy and you are backtracking with the same accuracy, you can be anywhere up to 20' off track but it is still much more accurate than navigating in the dark without the GPS.

I imagine that different units have different capablilities but I know that my Rino will track my speed below .5mph but you will see some variation +/- a tenth or two.

Bob

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The GPS will track the different position of a boat at slow speeds but it may not be able to show the arrow pointing in the correct direction. Your speed will record some what accurately even if the arrow is not pointing the same direction all the time. The speed is calculated in the computer by measuring the distance from one point to the next. No matter how slow you are moving, the unit will still record a different position and speed every second. The faster you are traveling, the further the points will be apart. The computer connects the dots and makes a straight line. The track it creates will not be as clean at one mile per hour as it will be a 60 and at slow speeds, the arrow will randomly point in every direction or it may only point in the last direction in which you traveling over a given speed (3 MPH for your H2O) . At slow speeds, more points are recorded per distance traveled. This may make the track appear not straight if you are going slow and zoomed in too far.

By the way, some of the more advance professional equipment like the Trimble, SatLoc and Racal units I have used would let you lower the threshold for travel (maybe it was the software my company made that allowed the change). See if the Manuel tells you how to lower the 3 MPH setting. I have an H2O and a Lowrance LCX-17M but I hardly ever read the manuals so I do not know if you can lower the track speed.

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I have never used GPS or a marker. I just rely on knowledge of the lake and other means, whether I be on Mille Lacs or a small lake.

I seem to do fine anyway.

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Nice answer Mpester. I can't see anything in the manual about lowering the speed setting, but there is something called "track smoothing." It says to leave it on when going at slow speeds, which is the default position of the setting.

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Hit your menu button two times go into "Utilities", hit enter. go into trip calculatorand change the speed threshold. Chances are if you havent changed it from the factory it is set on 5 mph. change it down to the lowest number you can get it to accept, probably 1 or possibly 00001. either way it should work better for you as it will register a much slower speed. If you are going to use it in you car or some place else you will probably have to move it back up to 5 mph. I was having the same problem as you when I was out drifting the other night, couldnt get it to show me where the (*&*%# I was at, only had about a 5 mph wind so was drifting very slow,really made me wish I had thrown a marker in that time. so I stopped in St.Cloud and talked to the gps guru and he gave me the above info.Hope it solves our problem

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I found the setting you described and changed it to 1. I hope it works! Thanks.

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