Hot maps & Lowrance GPSi 522C doesn't

Discussion in 'Fishing Electronics Review' started by Phil50, Jul 31, 2007.

  1. Phil50

    Phil50 New Member

    Messages:
    42
    State:
    Il
    seem to be very accurate. On a recent fishing trip to a lake, I noticed the track the 522C was recording was off by at least 50ft, maybe more. I could be 20-30 feet from the bank and the track on the screen had me 20-30 feet on the bank.

    I I got to checking more of the landmarks and everything is quite a ways off. I switched to Lowrance Data (maps) and everything seemed to be very close to my actual position.

    This has been noticed on just one lake, but have only had it on two lakes. Never noticed it on the other lake.

    Any one seem this before?

    My version of Hotmaps is 2004.
     
  2. peewee williams

    peewee williams New Member

    Messages:
    3,111
    State:
    Pembroke,Georgia
    GPS is wonderful!I bought Garmin & then bought Lowrance when they first came out with the IMS Inland Mapping System.I would advise anyone with a new unit to set it up in your vehicle and drive while paying attention to your tracks going and coming.You may need to slow your unit down with your tracking points.I found that some days I would vary as much as 100+ yards on the same 2 lane road.Sometimes It took months before it would do this once and go right back to normal.Just remember this always and you can safely use it.It is right to almost right most of the time.Severe storms with torrential rain when you may need it the most is often when it will lose its signal.I love you Brothers and Sisters.peewee
     

  3. jim

    jim New Member

    Messages:
    2,579
    State:
    Jacksonville NC
    Before you start navigating with your unit turn to the satellite page.That will tell you how many sats the unit is tracking and also give you the accuracy it is achieving at that moment.Depending on where you are and how many sats you are locked on to the error can be relatively large.Remember when SA was turned on the avg error was 100mtrs.Now 100ft is acceptable but most units will get you an avg of 30ft.Once again depending on the variables, accuracy can be within 10ft.Anything more than that and you need DGPS or WAAS.THis is why most units have a disclaimer page or pop-up that says not to depend solely on that unit for navigation.:smile2:
     
  4. Mr.T

    Mr.T New Member

    Messages:
    2,553
    State:
    MO
    I've got the 2007 HotMaps Premium for my area and according to the display, I spend a good deal of time on the shore while running wide open down the middle of the Missouri River channel.

    I spent a couple of hours one day on the phone with Navionics and Lowrance, neither would admit any fault or acknowledge that there was anything wrong with their units, even when I sent them screen shots of trails I'd made that showed me way up on dry land. The problem seems to be in the Navionics data from what I can tell, as I get the exact same results from two different sonar/GPS units.

    I frequently pass under bridges (in the real world) and then see the boat pass under the bridge several hundred feet later. My boat can be sitting on the ramp and the map shows me at least a hundred feet away.

    Same results on Truman Lake and the Lake of the Ozarks. I spent 20 minutes one day looking for a hump depicted on the map that was nowhere to be found - I searched about a half-mile in each direction.

    And yes, I've verified the accuracy of the GPS unit. It's working quite well - any waypoint I save stays exactly where I put it and I can follow any trail I've made and know I'm going exactly where I want to.

    I wouldn't blindly navigate according to the maps for love or money.
     
  5. jim

    jim New Member

    Messages:
    2,579
    State:
    Jacksonville NC
    Well as they say in map making, Data, Data, Data.!:roll_eyes:probably most of the data is old data except for the newer recently surveyed lake data on the HMP edition.SO if the day the data was gathered the GPS error was 150 ft then that channel marker isnt where it really is on the map.Then add the error for the day you are using the unit and voila you and the channel marker are now side by side in your boat OR you are driving up the shoreline.I seriously doubt Hotmaps sent a team of surveyors out and verified every inch of shoreline etc so as T says proceed at your own risk.One day we will be able to utilize commercial overhead assets and you will be able to real time plot yourself on any body of water under the coverage.By addition of a chip to your unit or boat you will actually be able to identify yourself proceeding down the lake or river.With zoom capability you will be able to see your self wave:big_smile::wink:Nighttime?No problem thermal image!:crazy:So quit fooling around in the boat!!!!!!! Now I'm not sure how fog and rain will work but I'll bet that same disclaimer will come up on your unit.:smile2:
     
  6. GMC FishHauler

    GMC FishHauler New Member

    Messages:
    1,335
    State:
    Waco, Texas, Un
    i have not tried to use a ff/gps yet. I have my gps that i bought while in the army and it is VERY accurate. It is a Garmin Rhino and i just compare it to the lake map i have and it works great. Problem i seem to be having is that the lake maps that i find are not that accurate. The boat ramp that i lauch at on lake limestone is over 100m off on the map. I have used intersection and resection to find that it was not just my eyesight or perspective that was making it look off it was just mislabled on the map.
    One thing about GPS is that sometimes if you are traveling at full speed it takes awhile for the info to catch up to you, other times the GPS unit assumes where u are heading and puts ur location at an assumed point to cover for the lapse in the time it takes for the satalite to position you.
     
  7. Phil50

    Phil50 New Member

    Messages:
    42
    State:
    Il
    Thanks for all the replys. I also think it's the Hot maps data, because I can switch off the Hot Maps data and just use the Lowrance Maps and the error seems WAY less.

    Now I'm not sure I'll buy a newer version.

    Thanks again everyone.