Standard Gps Accuracy

[Ohio Archer]

Hello.  New to the forum but have been watching it for a while.  It helped me decide on the new HB Helix 7 SI GPS with a Lakemaster card.

 

That brings me to my question:  what is the standard accuracy y'all are seeing with these units?  What I mean is how close to a ledge, hump, point, etc does the chart show you being at compared to where you actually are?

 

Using the Lakemaster card my Helix shows me between 30-50 yds off (maybe more) compared to the real-time sonar readings.  The chart shows me coming off or onto a ridge long before or after the sonar shows the change.  Is this normal?

 

Thanks for posting all the SI/DI photos and interpretations.  They are making learning this new unit a lot easier. 

[gulfcaptain]

Most GPS units get you within 15-30yds.  At least that's what they used to be.  They aren't going to be within a few feet due to wel safety reasons from my understanding.  But if you have a waypoint plugged in it will get you to that waypoint but as for chart plotters, I use a Furuno comercial unit with a Navtronics card at work on the crewboat I run and at times it will show me navigating on land going in and out of the channel/bayou here in the Gulf of Mexico depending on how close to the side of the channel I am.

[Wayne P.]

Is the location a Lakemaster High Definition Survey or one of the other two map sources?

[Wayne P.]

BTW, you should get at least 10 FEET accuracy with the GPS.

The map quality is probably your issue.

I get 1' - 4' accuracy with my Humminbird units.

[Jeff H]

I couldn't say in terms of feet or yards but my Lowrance HDS7's are pretty darn tight on the waypoints.  Mapping is really pretty good on most lakes I fish though some are way off.

[Ohio Archer]

Wayne P., on 22 Nov 2015 - 5:31 PM, said:

Is the location a Lakemaster High Definition Survey or one of the other two map sources?

According to the Lakemaster listing it is HD (bold but no asterisk).  Caesar Creek, Warren Co, OH. 

[Wayne P.]

According to the Lakemaster listing it is HD (bold but no asterisk).  Caesar Creek, Warren Co, OH. 

If it is just the High Definition Survey, it is not accurate and is not done by Lakemaster.

There are three levels of maps, only one is actually done by Lakemaster--Lakemaster High Definition Survey.

Like other digital mapping software products, some locations are purchased from "other sources" to have more content than the data they have.

 

Don't bet your life and property on the accuracy of any of them. Trust what your sonar is showing you.

 

I purchased a High Definition Survey location via Chart Select and it is a joke.

There are features that are physically impossible and certainly were not a result of any on-the-water surveys.

Either Lakemaster created the fake details or they were purchased from another company like the Standard Survey locations are.

 

Mapping companies have software that create contour lines based on nearby features, either a non-HD map with some contours or the shape of the shoreline. That is called Interpolation.

 

Even their own surveys do not have 100% coverage as they do not collect data for every square foot of terrain. They collect data in intervals and the software fills in contours between the data points. 

 

All mapping is like that with either computer generated features or manually done.

[Ohio Archer]

Thanks for the info, Wayne.  I can live with incorrect location on the chart.  It will get me close then I'll use the sonar.  Truly liking this Helix a lot.  Spent most of my day Saturday running over points, humps and bars just trying to learn all the features.