Interstates: Prefer/Avoid

This is still a bit of a mystery regarding Routing Options on my Lowrance iWay 500c.

If you set the slider near the "Prefer" end of the scale, the unit goes out of it's way to take you on Interstates, sometimes when that doesn't make much sense to me.

But worse yet, that command seems to drag other roads with it; it doesn't apply only to interstate highways. There seems to be a hierarchy of roads built into the system. Basically, it's like this: big roads to little roads. More specifically, something like this: Interstates, Federal highways, State highways, main county highways, county roads, and finally dirt roads.

If you are "preferring Interstates" it seems to avoid smaller roads like county roads. It has this influence even if you are miles from the nearest Interstate and it has nothing to do with getting to your destination.

My preference would be that the "Interstate" slider only pertained to Interstates!

And the opposite is true, too. If you set it to "Avoid" it'll never put you on one, but will plan routes on smaller roads.

The big question: will setting the slider in the middle make all roads equally available, that is, neither favoring nor discriminating against big roads or small roads? Logic would dictate that to be the case, but experience seems to indicate that you have to be set toward "avoid" to get any small roads in your route to the destination.

What's been your experience with your Lowrance? Click on "Comments" below and chime in.

This weekend, we'll be driving from Cedar Rapids to Owatonna, MN. Perhaps some more information on various operational subjects will be gathered.