Piloting W/ Navionics Getting a fix?

[JackRobinson]

Sailing costal with Navionics on my iPad. It's important to check the accuracy by using traditional piloting techniques ie, getting a fix using compass sightings and transits.
I can see where Navionics thinks I am, and I can sight landmarks and get compass headings. But to get a fix I need to overlap as least 2 vectors on the chart. On a paper chart I just draw the vectors, but I want to do this on the screen.
Navionics has the tool where you can draw a heading and distance line. But it only allows one line at a time. So I can't get a fix by overlapping 2 or 3 lines. If only they would let you draw 3 lines, you could get your own fix through sightings.

Is there a way to do this that I don't know about?
Or does another app do this?

[wholybee]

Originally Posted by JackRobinson

Sailing costal with Navionics on my iPad. It's important to check the accuracy by using traditional piloting techniques ie, getting a fix using compass sightings and transits.
I can see where Navionics thinks I am, and I can sight landmarks and get compass headings. But to get a fix I need to overlap as least 2 vectors on the chart. On a paper chart I just draw the vectors, but I want to do this on the screen.
Navionics has the tool where you can draw a heading and distance line. But it only allows one line at a time. So I can't get a fix by overlapping 2 or 3 lines. If only they would let you draw 3 lines, you could get your own fix through sightings.

Is there a way to do this that I don't know about?
Or does another app do this?

You could do this with OpenCPN, but OpenCPN isn't available on an iPad.
If you are in an area where Navionics charts are accurate (most of the world) then Navionics will be far more accurate than you can get with plotting a fix manually. You can manually plot fixes for the exercise and/or to prepare for when the iPad fails, but I don't believe the accuracy needs checking. I would do those exercises on a paper chart, not a tablet.

[requiem]

This is one of the reasons I like SEAiq; I can drop as many EBLs and VRMs as I like. Want to plot a visual fix? Just draw the vectors, put one end on the landmark and move the other until the bearing matches.

Add a mark at the proper spot and label with the time and fix type.

[wingssail]

Originally Posted by wholybee

You could do this with OpenCPN, but OpenCPN isn't available on an iPad.
If you are in an area where Navionics charts are accurate (most of the world) then Navionics will be far more accurate than you can get with plotting a fix manually. You can manually plot fixes for the exercise and/or to prepare for when the iPad fails, but I don't believe the accuracy needs checking. I would do those exercises on a paper chart, not a tablet.

Navionics charts are not accurate where I boat, and one of my friends dented his keel on a rock which was not shown on a navionics chart.

But the OP highlights a significant shortcoming in Navionics software, inability to show two or more ERBL. There are others, such as limited ability to reuse waypoints or establish waypoints by lon/lat, or used established waypoints in a route, and the absolutely stupid expectation that you establish a waypoint WITH YOUR FINGER! How is that for accuracy?

Navionics is getting better, but it is still a joke. The fact that it does not provide the basic tools for navigation is ridiculous. Burn it.

[wingssail]

Originally Posted by wholybee

You could do this with OpenCPN, but OpenCPN isn't available on an iPad.
If you are in an area where Navionics charts are accurate (most of the world) then Navionics will be far more accurate than you can get with plotting a fix manually. You can manually plot fixes for the exercise and/or to prepare for when the iPad fails, but I don't believe the accuracy needs checking. I would do those exercises on a paper chart, not a tablet.

Wholybee, what about the cautionary note, "Not to be used for navigation."

Safe navigational practices are not "exercises".

[ChrisJHC]

You can do it in Navionics but it’s pretty clunky.

I’ll use a 2-point fix as an example:

1. Take your bearings and convert to Degrees True.
2. Create a three point manual route as follows:
a. Start point where you think you are
b. First waypoint on one of the points you used for a bearing
c. Second waypoint on the second point you used for a bearing
d. End point back where you think you are (Don’t put it exactly on the start point).
Note that the start and end points don’t have to be accurate.
3. Now adjust your start point so that the bearing to the first waypoint is what you’ve calculated. Also extend the line so it is well past your guesstimate of your position.
4. Then do the same from your second waypoint to the end point. Also extend this line longer than you think.

Voila - you’ve now done a two point fix!

Obviously you can do the same for a three point fix with more legs in your route: