Not 18.4, RRS 10.

Not RRS 10 (yet).

No contact.

No avoiding action by Red.

Yea I guess so ... would be nice to see Red wiggle. 

Of course, it is a theoretical case that we discussed with my students.
Let's see now with the new position 4.
For me in this case, blue doesn't break any rules.

What do you think ?
THANKS !!!

As John A rightly points out (assuming these boats are not on a plane or otherwise moving at high speeds), given the boats are separated by 1 boat-width, Red needs to alter course toward Blue to initiate a potential rule-breach.

For Blue to be breaking RRS 10 at #4, Red would need to claim [show] that Blue was not keeping clear .. and that would require the conclusion that immediate contact would have occurred between the boats had Red altered course toward Blue.