Out of bounds – Rule 18
It’s almost guaranteed that nearly every golf course will have some form of external out of bounds (OOB), and some will even have internal OOB, perhaps on a dogleg where a direct route to the green could present a safety hazard to golfers on another hole. In either instance, if your ball comes to rest beyond the boundaries of the course, even if only by a millimetre, you are not allowed to play it, whether or not the ball itself is sitting in a perfectly playable spot.
The difference between being OOB or not can sometimes be a mere hair’s breadth, so where is the cut-off point? Well, OOB can be defined in a number of ways, most commonly by stakes or lines on the ground, which are usually white.
But it can also be defined by fences, walls, railings, ditches, or other similar features, so it’s important to know the point at which the course ends. Where a boundary is defined by white stakes or a fence, the OOB line is the nearest inside points at ground level of the stakes or fence posts. Your ball is in bounds even if only a small part of it overlaps the course side of the boundary line, meaning that if any part of the ball still touches the course, the ball is still in bounds.
It can sometimes be hard to decide if a ball is in or out with the naked eye, so some Referees will carry a piece of string around with them to assist with those close calls, as Justin Rose is demonstrating here. When OOB is marked by a white line on the ground, the line itself is OOB, but if any part of the ball is lying on the course side of the line, then it is still in bounds.
If your ball is found OOB, you must proceed under stroke and distance (Rule 18.2b) by adding one penalty stroke and playing the original ball or another ball from where the previous stroke was made. This is why it is always a good idea to play a provisional ball if you suspect your ball may have strayed OOB, as it will save you time and a potentially long walk back.
It’s also important to know that objects such as stakes that are used to define OOB are deemed to be fixed and you are not allowed to move them to make it easier to play your next shot. However, if you do remove a boundary object, but then realise your error, you will not be penalised if you put it back to its original position before you play your shot.
Finally, it’s also worth knowing that you are allowed to stand OOB to play a ball lying in bounds.
“IF YOUR BALL IS OOB YOU MUST PROCEED UNDER STROKE AND DISTANCE”