Guidance to Referees and Players on Short Range Clearances
Guidance to Referees and Players on short range clearances
Appendix 4 of the 5th Edition CA Rules booklet provides guidance on refereeing short range clearances which are capable of giving rise to the commission of faults.
The guidance on a stroke which involves hitting a ball towards another ball along or close to their line of centres is set out in paragraph 1.1 of Appendix 4. It is soundly based on the super slow-motion videos made by the CA in 2006.
When a ball is struck at an angle to a nearby ball the situation is more complicated and a summary of the guidance is set out in paragraph 1.2 of Appendix 4. Bill Arliss's DVD "The practical side of GC Refereeing" covers this subject in some detail including some new video analysis. The guidance on angled clearances given below is distilled from chapter 5 of this DVD.
Refer to the diagram and note the following abbreviations used:
- Aiming Angle to line of ball centres (AA) in degrees
- Initial Separation (IS) of the balls in millimetres
- Departure Angle (DA) - the angle in degrees at which the balls separate after impact
The following guidance assumes well-executed stop shots. Note always that poorly played strokes with excessive or lazy follow-through will be likely to cause a fault even in circumstances when a well-executed stop shot would not - this must be taken into account when refereeing a stroke.
Video evidence has confirmed that a Double Tap 'Ball Crush' will generally reduce the DA of the two balls after contact. In a clean stroke, the DA is something between 65 and 90 degrees; in a fault, the DA will be less than 60 degrees - it is this fact which can be used to decide the fairness of strokes.
There are many potential situations, which have been generalised into these three groups to aid players and referees:
- Straight or nearly straight strokes:
If AA is < 10, treat the stroke as though it were straight and apply the guidance in Appendix 4 paragraph 1.1.
- Angled strokes with balls separated by at least 3mm and where both balls move more than 600mm:
If AA > 10, then if DA < 60 the stroke should be faulted under Rule 11.2.4 or 11.2.6.
- Gentle or very angled strokes with small initial separations:
- unless both balls move an appreciable distance, it is difficult to tell anything useful from DA. Instead, before the stroke is played, ask the player to indicate the intended line of aim and estimate how far the relevant point on the SB's perimeter will travel before it contacts the OB. If <4mm, the stroke should be faulted under Rule 11.2.6.
- using the approach in 3.1, the smaller the IS, the larger the AA required to avoid a fault.
- With IS = 2mm, the stroke must be played with AA > 60 degrees to avoid a fault when played with a stop shot and AA > 70 when played with a full drive
- With IS = 1mm, the stroke must be played with AA > 75 degrees to avoid a fault.
When played correctly at such extreme angles, the OB will not move very far at all - if it moves a significant distance, then there is likely to have been a fault under Rule 11.2.6.
How to Referee Such Strokes
- Ask the player what they intend to do. The referee needs to know:
- what is their intended line of aim and hence what AA they intend;
- the type of stroke that they intend to play (i.e. stop shot or drive); and
- how hard they intend to play the stroke.
- Check the separation between the balls along the line of centres. If the separation is <3mm, also check how far the relevant point on the SB's perimeter will travel parallel to the intended line of aim before it contacts the OB.
- Mark the initial positions of both SB and OB. Be ready to mark the departure directions of both balls. Ideally, ask the opponent to mark the line of the OB (because that is relatively insensitive and will not deviate very much from the initial line of centres) and an assistant to mark the line of the SB.
- Ask the player to play the stroke.
- Watch the stroke - was it along the intended AA, was it a well-executed stop shot? Consider the DA.
- Apply the guidance given to decide whether or not to declare a fault under Rule 11.2.4 or 6.