Modeler3D, perhaps you can try a small experiment and work your way up, like:
1.) Open a copy of the your drawing of your fence.
2.) Set a point.
3.) Draw a sphere that has the same radius as your rope on the point.
4.) Group it.
5.) Make 3 copies of the point/sphere you made.
6.) Using the Gumball widget, move them somewhere along the surface where you want to create a rope.
7.) Make sure your Point snap is on.
8.) Using InterpCrv, draw a curve to connect the Points in the center of the curve (You can undo the last segment, if you need)
9.) Select the curve you just made.
10.) Make a pipe.
If you use Record History, you may be able move adjust the Curve by moving the Points.
If you use Record History, you can surely adjust the pipe by moving the curve nodes.
My mantra was:
To a large degree, the path of the rope can be represented by it’s center line,
Other than the tension, the path of the rope is determined by where and what it contacts.
In the examples above, I used circles to represent the edges of the rope so I can determine where it makes contact, but It would be handy to group points in the center of the sphere’s.
Basically, you can place circles where you think the rope would make contact, and use InterpCrv to connect them. The circles–or better yet, spheres just become 3 dimensional nodes, or nodes with a known offset.
In the example below, I lifted the pipe after it was done, so you can see the underlying curves, spheres, and points. This was just a quick, crude drawing, but I hope you get the idea.
Basically you are manually making collision spheres for a self colliding object.
You can get fancy. In the instance above, you could have just used Section command to create a profile of the object–even diagonally, and then Trim it to keep the part you want, and then Offset it for the radius of the rope, and then deal with the ends, perhaps by using straight lines and then matching them or radiusing them.