New Chart Plotters Compared to Older NORTHSTAR

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Small Boat Electrical
  New Chart Plotters Compared to Older NORTHSTAR

search | FAQ | profile | register | author help

Author Topic:   New Chart Plotters Compared to Older NORTHSTAR

jimh posted 05-16-2015 09:34 AM ET (US)
I [am] curious whether the newer chart plotters offer a chart offset. The Northstar 95X units offered a chart offset in the menu. Basically move the cursor to where your boat's position should be relative to the chart and set the offset. I found this useful for a creek that I traveled through for every trip, and often that was done at night and in fog.
jimh posted 05-16-2015 12:59 PM ET (US)
In the device you refer to, was the offset applied to the position deduced by the GNSS receiver? Or was it applied to the chart data?
I have a first-generation Lowrance HDS chart plotter. As far as I know, it has no similar feature.
porthole2 posted 05-16-2015 06:16 PM ET (US)
Position left intact, the chart could be shifted to match where your position is relative to a land mass.
For example, I saved two waypoints while in the middle of a bridge passage. Split the difference between the two waypoints and then "moved" the chart to match the center of the bridge over my waypoint.
jimh posted 05-17-2015 07:29 AM ET (US)
That option actually sounds a bit scary. Moving the reference plane of the digital chart could be dangerous. It makes an assumption that every part of the earth covered by the chart is in the wrong location by the same offset. In the case of a channel of a waterway, the channel may have just wandered due to natural changes, while the rest of the earth positions did not.
porthole2 posted 05-18-2015 09:48 AM ET (US)

quote:
Moving the reference plane of the digital chart could be dangerous.
So could blindly accepting that the supplied charts are accurately placed on the chart plotter's reference GPS position.
My example was one small area that I traveled through 70-100 times a year, a narrow winding creek. I was not suggesting that people go out and start shifting their charts around. With the Northstar units it was a simple few keystrokes to make the shift - or remove it.
jimh posted 05-19-2015 04:02 PM ET (US)
What basis makes you think your several-generations-old GPS receiver is more accurate than the published charts?

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

Author	Topic: New Chart Plotters Compared to Older NORTHSTAR
jimh	posted 05-16-2015 09:34 AM ET (US) I [am] curious whether the newer chart plotters offer a chart offset. The Northstar 95X units offered a chart offset in the menu. Basically move the cursor to where your boat's position should be relative to the chart and set the offset. I found this useful for a creek that I traveled through for every trip, and often that was done at night and in fog.
jimh	posted 05-16-2015 12:59 PM ET (US) In the device you refer to, was the offset applied to the position deduced by the GNSS receiver? Or was it applied to the chart data? I have a first-generation Lowrance HDS chart plotter. As far as I know, it has no similar feature.
porthole2	posted 05-16-2015 06:16 PM ET (US) Position left intact, the chart could be shifted to match where your position is relative to a land mass. For example, I saved two waypoints while in the middle of a bridge passage. Split the difference between the two waypoints and then "moved" the chart to match the center of the bridge over my waypoint.
jimh	posted 05-17-2015 07:29 AM ET (US) That option actually sounds a bit scary. Moving the reference plane of the digital chart could be dangerous. It makes an assumption that every part of the earth covered by the chart is in the wrong location by the same offset. In the case of a channel of a waterway, the channel may have just wandered due to natural changes, while the rest of the earth positions did not.
porthole2	posted 05-18-2015 09:48 AM ET (US) quote: Moving the reference plane of the digital chart could be dangerous. So could blindly accepting that the supplied charts are accurately placed on the chart plotter's reference GPS position. My example was one small area that I traveled through 70-100 times a year, a narrow winding creek. I was not suggesting that people go out and start shifting their charts around. With the Northstar units it was a simple few keystrokes to make the shift - or remove it.
jimh	posted 05-19-2015 04:02 PM ET (US) What basis makes you think your several-generations-old GPS receiver is more accurate than the published charts?