Used correctly, it is one of the biggest time-savers in golf, and on any shot where there is reasonable doubt as to whether or not the original ball is likely to be found or may have gone Out of Bounds (other than if it has clearly gone into a water hazard) you should play a provisional ball both for your sake and the sake of other golfers. Never be embarrassed to hit a provisional, especially if you are playing a medal where every shot counts.
If you wish to play a provisional ball you must inform your opponent, marker or fellow-competitor that you intend to do so, and you must play it before you go forward to search for your original ball.
It is essential that you clearly state it is a provisional ball, with phrases like “I’ll just hit another” or “I think I’d better reload” failing to cut the mustard in the eyes of the Rules.
If you fail to state that is it is a provisional ball or that you’re proceeding under Rule 27-2, the ball you then hit automatically becomes the ball in play under penalty of stroke and distance (Rule 27-1) and the original ball is deemed lost even if you subsequently find it in the middle of the fairway.
If the original ball is lost (other than in a water hazard) or out of bounds, you must continue with the provisional ball, under penalty of one stroke.
If, however, the original ball is found in bounds, you must continue with that ball and stop playing the provisional ball.
Remember, you can continue to play your provisional ball until you reach the place where the original is likely to be, but if you make a stroke at it at that point, it becomes the ball in play and the original is rendered lost.
We’ve all played with people who seem reluctant to hit a provisional ball when everyone else is thinking “there’s no way we’re ever going to see that one again!” so don’t be afraid to prompt others into playing a provisional if you feel able to, as it will potentially save everybody time both in your group and the groups behind.
One final thing – at some stage you will find yourself playing with someone who thinks that you have a choice over which ball to play should the original be found in an unsavoury spot.
You don’t – if the original is found, the provisional ball is irrelevant and you must proceed with the original either by playing it or invoking one of the three options under the unplayable ball Rule (Rule 28)… and then politely pointing them in the direction of The R&A’s online Rules Academy.