1. Find (and then declare) what the pertinent facts are about the incident
2. Conclude what if any rules were broken by which boats and if those boats are exonerated for breaking those rules
3. Decide what the appropriate penalty is for any unexonerated breaches of the rules and if a penalty is to be applied by the PC (sometimes a boat already took the appropriate penalty). 

1. Blue on S and Yellow on P were on a beat to windward on converging courses during the 1st windward leg.  
2. Both boats were J/105's traveling at 6kts in 10kts of breeze (10.5m/34.5' BL, 3890kg/8576lb min-WT).
3. Had both boats each held their course when Blue was 2 BL's from Yellow, Blue's bow would have made contact with Yellow's starboard rear quarter 1 foot forward of Yellow's stern. 
4. From when the boats were 1-3/4 BL's apart until they were 1 BL apart, Blue altered course to starboard and Yellow altered course to port [starboard] in response to a wind shift.  This moved the course-intersection point forward to mid-ships on Yellow's starboard side. 
5. Blue's bow made contact with Yellow's starboard side at mid-ship. 
6. From 1 BL separation until contact occured, neither boat altered course.
7. Contact caused a 5"x4" indentation in Yellow's hull at the toe-rail with fractures in the fiberglass skin. There was no damage to Blue.  There were no injuries on either boat.  

1. Y on port tack did not keep clear of B on starboard tack.  Y broke RRS 10.
2. B, a right-of-way boat changing course did not give Y room to keep clear.  B broke RRS 16.1.
3. Y, sailing within the room to which she was entitled was exonerated for breaking RRS 10 by RRS 43.1(b).
4. It was not reasonably possible for Y to avoid contact.  Y did not break RRS 14.
5. It was reasonably possible for B, acting no sooner than it was clear that Y was not keeping clear, to avoid contact and she did not do so.  B broke RRS 14.

• When [boats ar  so close that] a right-of-way boat needs to take avoiding action (Case 50), and does so by changing course, the give way boat has already broken the relevant right-of-way rule, so the right-of-way boat’s change of course is not denying her room to keep clear, and the right-of-way boat does not break RRS 16.1.
• So unless the protest committee concldes that , whe the right-of-way  boat changed course,  boats were so close that the right-of-way boat needed to take avoiding action, and that changing course as she did was avoiding action, RRS 16 applies when she changes course.

Restating the second scenario and using Angelos approach...

Facts Found:

1. Blue on starboard and Yellow on port were on a beat to windward on converging courses.
2. Both boats were DF95 (2kg) in 5 kts of breeze.
3. Had both boats each held their course when Blue was 2 BL's from Yellow, Blue would have hit Yellow aft of midships.
4. From when the boats were 1-3/4 boat lengths apart until they were 1 boat length apart, Blue altered course to starboard and Yellow altered course to starboard in response to a wind shift.  This moved the course-intersection point forward to mid-ships on Yellow's starboard side.
5. Blue's bow made contact with Yellow's starboard side at mid-ship.
6. From 1 boat length separation until contact occurred, both boats continued to alter course to starboard.
7. There was no damage to either boat.
8. Yellow performed a 360 penalty turn.

1. Yellow on port tack did not keep clear of Blue on starboard tack.  Yellow broke RRS 10.
2. ...?

1. In 5kts of breeze, how fast does a DF95 travel in terms of secs/BL?
2. How many sec's does it take a boat to do a 'fast tack' and a 'normal tack'?

• Unless the boats are sailing absolutely parallel to each other, all courses are 'converging', the course lines will cross somewhere, just a question of where.  The description of a 'collision' course gives you the idea that at some point, presumably soon, the boats will be trying to occupy the same space at the same time.  Adding where the contact would occur gives you a bit more context.  The notion of a collision course to me says that the keep clear boat will have to take some sort of action before they reach that point.
  
  
• There is a match racing call (2021.001 Question 3) that says:
  Rule 16.1 is a limitation on Blue to allow Yellow to continue to fulfil its requirement to keep clear when Blue changes course. Rule 16.1 can only be broken when Yellow is keeping clear before Blue changed course. In this case, Yellow was not keeping clear prior to Blue changing course; therefore, Blue did not break rule 16.1.
  This covers the question about rule 16 when Blue alters course and Yellow is already not keeping clear and breaking rule 10.  Note that Blue could still be found to have broken rule 14.
  
  
• Changing speed is not a change in course unless you change between going backwards and forwards.  That is a change in the course that you are sailing.  Changing speed happens all the time as boats surge, surf, or plane on waves.  The keep clear boat is required to expect that a ROW boat may do that in the existing conditions.  It's about the only thing in the rules where the keep clear boat is required to anticipate what the ROW might do.   When boats submarine, which happens often in RC boats, and in not even that strong a breeze, the boat is generally changing course as they pivot and 'fall over'.  You might be able to make an argument that they were changing course and didn't give the other boat room to keep clear.  That would be an interesting case but I would hope that the rules gods would not go for that argument.
  
  
• In addition to Case 147, there is also case B3 in The Call Book for Radio Sailing, that talks about a boat "unbreaking" rule 16.1.  That is a very interesting case as rule 18.3 doesn't apply because P never completes her tack.  But that is another thread.

The initial state was 'not in a collision course', but what happen when the boats are subject to sudden speed change because they are too light? The problem could be similar to a nose diving in a downwind high speed catamaran port/tack cross, where initial calculations are not enough taking only the course angle in the formula.