I've been teaching the RRS for some years now and whilst 10-17 are pretty good rules, but I find that 18, 19 and 20 are just too complex for casual sailors to comprehend off the water, let alone whilst racing. 

Some clubs instead use colregs, but they are entirely unsuitable for contested marks.  Ultimately we end up teaching simplifications like "just go round the outside". This is a safe simplification, but it's not ideal to have to tell the competitors that it is best to ignore the details of the rules!

So I'm wondering if it is possible to come up with a simplification of 18, 19 and 20 for club racing that would be broadly compatible with the normal RRS.  Something that the majority of club racers could remember and apply on the water. 

This is my attempt:

These rules replace Rules 18–20 of the Racing Rules of Sailing for casual club racing.
All other rules, including Rules 10–17 on right-of-way and general limitations, remain unchanged.

(a) Marks of the course, other than starting marks, are treated as obstructions, and Rule 19S applies.
(b) If within her zone, a boat becomes the right-of-way boat through her own actions, then she shall give the keep-clear boat room to pass the mark.
(c) If a boat establishes an inside overlap within her zone, and the outside boat is fetching the mark, then the outside boat must not be forced to alter course to avoid contact.

At an obstruction, an outside right-of-way boat will give an overlapped inside keep-clear boat room to pass the obstruction, unless it was not possible to do so from the moment the overlap was established.

If a boat must tack to safely avoid an obstruction, she may hail other boat(s) for room to tack. The hailed boat(s) must respond as soon as reasonably possible by either tacking or hailing “you tack.” The hailing boat must then immediately tack.


The intention of these alternative rules is to let right of way do most of the work and only introduce an additional rule when a keep clear boat needs room.     Late tacking at marks is discouraged by 18(b). Late overlaps at marks is discouraged by 18(c). Hailing for room to tack at a mark is discouraged by making it only for safely avoiding an obstruction.  
 
Would these rules work?   How different in practise to the real 18-20 are they?   What are the problem cases?  Would there be a problem if boats racing under these rules interacted with boats under the normal 18-20?