Humminbird Helix 7 gps accuracy

[KS Cranker]

Over the winter I bought a Helix 7 gps sonar unit and installed it while getting my boat ready for the summer. I bought the Lakemaster Minnesota chip for it. While out on pool 2, I noticed the accuracy was off by about 20-30 feet to the east. It would show my location as being on shore while I was obviously a ways out in the river. I was looking through the settings on the menu to see if there was a way to calibrate the gps location but I didn't see anything. I haven't had my boat on a lake yet, so I'm not sure if the river map drawing was just inaccurate, or if the actual location was off. Has anyone else with this unit noticed an inaccuracy, or is it just me?

[LucasLongCaster]

If you contact them here: http://www.humminbird.com/Category/Company/Contact-Us/   they get back to you relatively quickly..I don't have a helix I have a 788hd di, but I have had to contact them about a few accessories and they have good customer service

[delcecchi]

The accuracy or actual position compared to map position can vary by up to maybe as much as 100 feet in any direction, depending on which satellites are in view or other factors. 

[h8go4s]

GPS location can vary, but I've never had that much error with a Lakemaster card, especially the lakes surveyed in 1-foot contours. That being said, don't go running in the shallows expecting every rock to be marked. But in your case, I wonder if you actually had the Lakemaster card selected or if you were using the built-in Uni-map, which is Etch-A-Sketch quality. I've seen pretty big errors on that.

[hayseed]

I don't have the Helix 7 but have a Helix 5 with Lakemaster chip. The only times I've noticed the difference your experiencing is on lake maps that are not HD. Most non commercial GPS units will only claim a 3-5 meter accuracy so I doubt they would claim any more accuracy than that. Certain weather conditions can also effect accuracy. 

[delcecchi]

Using a hand held I have walked a local bike path, turn around and walked back.  the two lines were 15 or 20 feet apart in some places. 

Also make sure that the "datum" you have selected is the same as for the map chip, if the unit allows you to select the datum.

Datum sort of defines the origin and grid for the map, and there are several different ones.  Here is a link to an easy to understand article that explains the two main datums and why it is important....

http://www.alpharubicon.com/prepinfo/mapdatumwmerrin.htm

[Jmnhunter]

hey KS, do you have some coordinates of where you were at? I can check it out for you, you can also PM if you would like

also, make sure you have the latest software update on your 7