If you look at the top part of this route, I think I can give a hint at what is going on.
The top point of each of those magenta lines - if you took a pencil and draw a line through them, that is probably your intended route?
I have seen this sort of thing before with a route that was plotted on a road that the Zumo didn't know about:
A new bypass. A route consist of your route points. It also has hundreds and hundreds of invisible 'ghost' points , which the Zumo has placed there. These are a few metres apart and the Zumo joins them together with straight lines to form the magenta route that follows the twists and turns of the road. Zoom in close enough you will see that any route is not curved, but a series of short straight lines.
When a route points is plotted in the middle of a field (by accident), the Zumo will visit it by plotting a straight line to it from the point on a road that is closest - at right angles to the road that it is travelling. If a whole route is plotted in the middle of a field (because as far as the Zumo is concerned, that road doesn't exist), it will calculate a route using a nearby road that does exist and when it gets as close as it can to the plotted point it will draw a straight line to that point. And then go back to the road that does exist.
How can it plot a route on a road that doesn't exist ?
Well one way is to plan a route using a new map (that contains the new by pass), and then send it to the Zumo which hasn't got the newer map installed. As far as the Zumo is concerned my route points are all in the middle of an open field. It has to visit each point in turn - but it has to do so along nearby roads that it CAN navigate, and then makes a straight line to the route point across the field.
The result looks similar to your screen shot. But it is not identical.
Your screen shot doesn't make sense until you consider the possibility that that single via point in the middle of the atlantic may be a lot of via points all plotted in the same place. If you think of it like that - then it looks similar to what I was trying to describe above.
Why so many via points all in the same place ? I don't know.
I can offer suggestions which may be relevant.
Some route planning software doesn't know about via points and shaping points. Mapsource is one. If you load a mapsource route, into any Zumo from the 590 onwards, it will have lots of via points in it. Other software that generates routes from (say) tracks, or from (say) google maps have a similar result.
Why a lot of via points in the same place ? I have really got no idea, but modern Zumos do alter the location of your route points when they receive them. I believe that this is so that routes created on other mapping software can still be processed to obtain a reasonable route. For example, you place a point in (say) Basecamp. It is not accurately placed and is actually a few 10s of metres in an adjacent field. On import the Zumo will look at the coordinates, find a known point nearby, look up its name and substitute that point for the one that you plotted. This can be seen in Zumos since the 595 when many route points have had their name changed, and their location is slightly adjusted.
I wondered if that point was on an island, but I cannot see one in that area. The point seems to be around the equator - made me wonder if it was 0,0 or something like that.
Absolutely anything is possible if
- The maps on the Zumo are not identical to the maps in the route planning software. Only Basecamp and Tread can guarantee that.
- Two maps are turned on in Zumo's myMaps that cover the same area.
- Route points are not accurately placed
- Your mouse has a dodgy microswitch under the button - dropping a point without you noticing.
I would be very intrigued to see the gpx file for this route.
It would also be useful if you can shed any light on what you might have done to create this issue eg what software did you use, what maps, was it converted from a track, from another route. Anything would help.
As I said numerous times, at the moment I really do not know. I have ideas which may be relevant or completely wide of the mark. I'm taking the trouble to write these down because someone else may be have other snippets that will help us to home in on the cause of this. This is how we cracked the RUT issue. So next time we see the same thing there will be a number of us that can say very knowledgeably - 'Ah yes, that is because you went to make a cup of coffee half way through planning your route, and while you were gone the cat walked across your keyboard.'