UPDATE: With additional troubleshooting, I've pinned down the problem, and found a workaround. See my new Reply.
I have both the Foretrex 401 and the Foretrex 601, and use them for both hiking and sailing.
They are great units in many ways, except for one huge flaw: They don't follow Routes!
For example, consider this course for sailboat racing:
The Start is at 3, and the course is 3-1-2-3.
In other words, it's a closed course with both start and finish at 3.
If you set 1-2-3 as a Route, and attempt to Follow it,
the Foretrex will set 2 as the first mark,
because it's closer than 1 to 3.
If you go to 1 regardless, the Foretrex will then set 3 as the next mark,
because it's closer than 2.
It does not matter whether the Setting for Routes is Auto or Distance.
This behavior is nuts, making Routes useless for navigation.
You have to do each leg manually.
And it's not just a problem for racing, as in this second example:
White is water, lower grey is land, the gray finger is a breakwater,
and it's a pitch black night.
Home is 3, and you're starting at 1, so you need a Route of 1-2-3
to avoid crashing into the breakwater.
But the Foretrex will send you from 1 to 3, because it's closer than 2,
and the result would be a disaster.
It's insane to go to closest Waypoint in the Route instead of following Waypoints in Route order!
It was bad enough that the 401 always had this problem, but the 601 has the same problem.
What were they thinking?!