Humminbird Side Imaging Forums
General => General Discussion => Topic started by: cemiii on February 03, 2012, 03:32:54 PM
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I've been getting wierd map views on my 798 ci si showing my boat routes way over land, etc. I have read up a bit and understand how to set the map offset feature, but I still have a couple questions.
1. It says that the offset is only good for that specific lake. Assuming my map contains many lakes why do I have to reset it for each lake?
2. It is a real pita to have to run miles to a bridge or something to reset the offset after having cleared it. Isn't there a simple way to save the map offset and not have to reset it at each lake each time? I boat on CA reservoirs with changing dock locations etc. due to falling water levels.
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You (may) have to reset it for each lake because while we see one map, the unit is actually looking at several maps all being displayed together for us humans. Some lakes and rivers will also be made of multiple maps, so an offset for one lake or area of a lake, may not be needed or correct for another lake or lake area.
I do not know of any other way to set the map offset feature other than to travel to a known location that is also shown on the map.
Are you using a map card?
Just how accurate do you need your map to be?
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CE check that you have set your unit map gps data to the one used by the map builder.
Wonder is the multiple map thing on a lake couple be using different gps datums and we are not told that..
chuck
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Greg, my mapping feature is several hundred feet off as best I can tell. Unfortunately the unit is on the boat at a vacation home and I have no internet there, but on my most recent run at New Melones Reservoir in CA, I ran the boat all over the lake and the track I left on the screen is at least 80% outside the boundaries of the lake. That is, right now it is navigationally useless.
I believe the current map is the Contour XD that came integrel to my 798ci SI HD combo.
Thank you, Chris
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Chris, check the map datum setting on your unit. I think it should be WGS84. If not change it to that Datum.
Chuck
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Thank you Chuck I will try that on my next trip as well as updating the software to 5.840 (though I don't think it does anything to the gps system).
I initially had all kinds of problems with the unit going totally squirrelly on me after a few hours of running my minn-kota trolling motor. I assume that was due to voltage. Adding a third battery in parallel seems to have corrected that. I doubt that that had anything to do with the gps problem which persists after increasing my battery system to 375ah.
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CEM, Yep I agree that this does not seem like a volt issue. Be sure to let us know on the datum thingy...
Chuck
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Greg, my mapping feature is several hundred feet off as best I can tell. Unfortunately the unit is on the boat at a vacation home and I have no internet there, but on my most recent run at New Melones Reservoir in CA, I ran the boat all over the lake and the track I left on the screen is at least 80% outside the boundaries of the lake. That is, right now it is navigationally useless.
I believe the current map is the Contour XD that came integrel to my 798ci SI HD combo.
Thank you, Chris
Chris,
Sounds like the internal ContourXD map is off for that lake. Not anything that Humminbird can do about that as the ContourXD maps were purchased from a mapping company. Your best bet for accurate lake maps would be to buy a mapping card from either Navionics or LakeMaster.
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Greg, are you saying that the internal countour xd maps that HB purchases are not right..? If so I would not buy any more of these and put them in your unit.
Or am I confused on how a countour xd is loaded internally...
Chuck
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Greg, are you saying that the internal countour xd maps that HB purchases are not right..? If so I would not buy any more of these and put them in your unit.
Or am I confused on how a countour xd is loaded internally...
Chuck
Chuck,
Cemiii said that he understood how to set the Map Offset function and that the maps were several hundred feet off. I’m guessing that this means that the internal maps are off for that reservoir. Now this could be due to the changing water level or it may be due to changes in the reservoir itself. The ContourXD maps are based on map data that is not current, so not knowing the area I am guessing that the reservoir has changed or possibly that the maps never were accurate to begin with. The way I see it our (Humminbird) options are (I do not speak for the company for this):
1. Leave the maps as is.
2. Eliminate the maps.
3. Replace the maps with current up-to-date maps.
The problem with #1 is that there will be fishermen who do not have an accurate base map in their units. This neither costs nor saves the company any money though it may lose some Customers.
The problem with #2 is that there are no base maps in the unit. This saves the company the most money though would probably lose many Customers for whom the base map was accurate enough and who want some sort of base map in their unit.
Option #3 would result in the most accurate maps but at what cost. First we would have to talk some map company into selling us their most current product (and hope it is accurate) and than we would have to pass that cost onto the Customer. I’m guessing that you would not want to pay for accurate maps for all of those lakes and rivers that you will never travel to as most would not. Than when new lakes are added or a body of water changes; these internal lake maps would have to be updated by some means. We would have to of course charge for this and would need some way of keeping the updated information from being posted on internet boards and passed from one unit owner to another. Too many headaches going this route.
The current method seems best to me: if the internal maps are not accurate enough for the fisherman’s needs, he needs to look into buying a mapping card that has more accurate data.
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I guess the question still unansered is the datum selection. If the unit does not match the map then the display will be off.
We run into this on SAR with sonar using WGS83 or 84 and the dog crews using NADS 27.
Maybe we shold leave mapping to the card makers and let the user buy the maps he wants. Navionics and others should consider smalling down their maps and having selection for the users needs.
Oh my. what would this cause.....
I guess that older maps could have lake elevation and contour changes so maybe it is time to get newer maps for internal...
Not to open another can of worms but what about loading google maps. or is this not possible....
Chuck
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I've been getting weird map views on my 798 ci si showing my boat routes way over land, etc. I have read up a bit and understand how to set the map offset feature, but I still have a couple questions.
1. It says that the offset is only good for that specific lake. Assuming my map contains many lakes why do I have to reset it for each lake?
2. It is a real pita to have to run miles to a bridge or something to reset the offset after having cleared it. Isn't there a simple way to save the map offset and not have to reset it at each lake each time? I boat on CA reservoirs with changing dock locations etc. due to falling water levels.
Chris at this time you are not going to get a map from anywhere that is going to be accurate when the reservoirs you are fishing drop an raise at that rate.You will need to adjust for each lake that is not at normal pool that is where they are normally
recorded.Sorry Gary