WHAT IS A PROVISIONAL BALL?
A «provisional ball,» often shortened just to «provisional,» is a second golf ball played by a golfer who believes his first ball (the stroke he just played) may be lost (but not in a penalty area or out of bounds).
Official Definition in the Rule Book
The USGA and R&A, golf’s rule-making bodies, provide this official definition in the Rules of Golf:
Another ball played in case the ball just played by the player may be:
• Out of bounds, or
• Lost outside a penalty area.
A provisional ball is not the player’s ball in play, unless it becomes the ball in play under Rule 18.3c.
Which doesn’t expand on what we already said above, so let’s expand!
Say you hit your drive and, whoops, it’s way left, deep into woods. You think, «I’ll never find that ball, it’s probably lost.» The penalty for a lost ball (or a ball hit out of bounds) is stroke-and-distance.
The «and distance» part means that if you are strictly adhering to the rules, after walking forward and searching for your ball, and confirming that it is lost or OB, you’d have to trudge all the way back to the spot of that previous stroke and play another shot.
Or, before you go forward to search, you can play a provisional ball. The purpose of the provisional ball, really, is saving time: Now, after hitting the provisional, if you go forward and search and can’t find that first shot, well, you’ve already put another ball into play. You don’t have to trudge back and re-play the shot, because you’ve already hit that provisional.
Rule 18 Covers Provisional Balls
In the rule book, provisional balls are covered under Rule 18 — specifically, in Rule 18.3, the third of three sections under Rule 18. Summarizing Rule 18.3 based on the Player’s Edition of the rule book:
«… if you are aware that the only possible place your original ball could be lost is in a penalty area, a provisional ball is not allowed.» That’s included in the first clause of Rule 18.3.
But if you are eligible to play a provisional ball and decide to do so, you must announce that intention. And you must use the word «provisional» in letting the other golfers in your group know what you are doing.
«If you did not announce this (even if you intended to play a provisional ball) and played a ball from where the previous stroke was made, that ball is your ball in play under penalty of stroke and distance,» the rule book states.
Rule 18.3c includes a diagram to help golfers recognize when that provisional becomes their ball in play. One way the provisional becomes the ball in play is by the golfer playing it from a spot nearer the hole than the original ball.
On the other hand, there are situations when you must abandon that provisional and play the original ball. Those include, quoting from the Player’s Edition:
When your original ball is found on the course outside a penalty area before the end of the three minute search time.
When your original ball is found in a penalty area or is known or virtually certain to be in a penalty area. You must either play your original ball as it lies or take penalty relief.
Again, this is just a summary of Rule 18.3, be sure to read the full rule for more detail.