RULE 18

Ball at rest moved

A ball is deemed to have moved if it leaves its position and comes to rest in any other place. It is how and when the ball comes to move, though, that determines whether or not you have broken any Rules.

If your ball is moved by an outside agency, such as a dog, a crow, or a greenkeeper driving his grass-cutter, then you incur no penalty. You simply replace the ball before you play your next stroke. If the outside agency makes a clean getaway with your ball, don't panic because you can substitute it by another.

From there on the Rules get a little more intricate. Once your ball is in play, if it is moved by a player, partner, caddie or piece of equipment then you immediately incur a one-stroke penalty, except if you are in the process of:

• Measuring to determine which ball is furthest from the hole.

• Searching for a covered ball in a hazard or for a ball in casual water or ground under repair.

• Repairing a hole plug or pitch mark.

• Removing a loose impediment on the green. Note that this refers to when you are on the green. If you're not on the green and you move a loose impediment within one club-length of the ball, and the ball then moves, you are penalized one stroke,

• Lifting a ball under Rule 20.

• Placing or replacing a ball under Rule 20.

• Lifting a ball interfering with or assisting play (see also Rule 22).

• Removing a movable obstruction.

If your ball moves after you've addressed it, you are deemed to be the cause and you incur a one-stroke penalty. You may recall that this penalty does not apply on the tee. This is one reason why it is advisable not to ground the clubhead if your ball is perched precariously. Remember that, outside a hazard, if you do not ground your club then, strictly speaking, you are not deemed to have addressed the ball and cannot be penalized if the ball moves.

When you are searching for your ball, say among fallen leaves or in deep rough, there is no penalty if your ball is accidentally moved by an opponent, caddie or equipment. That rule is the same in matchplay and strokeplay. Remember, though, you must replace the ball. If your ball is moved by another ball, you again replace it.

RULE 19

Ball in motion deflected or stopped

Once again, the interpretation of this Rule depends on the 'parties' involved. If, while your ball is in motion, it is deflected or stopped by an outside agency, this is classified as rub of the green. No penalty is incurred and you play the ball as it lies - but that isn't always going to work in your favour. For instance, if your ball bounces off a greenkeeper's tractor and into a pond, that's a particularly bad rub of the green. But if your ball bounces off that same tractor and straight into the hole, you won't be needing your putter on that hole.

As is often the case, though, there are exceptions to the Rule, if, anywhere other than on the green, your ball comes to rest in or on a moving outside agency (a passing dog, to give one example) then you drop a substitute ball as near as possible to the point where it was whisked away. No penalty.

If the same thing happens on the green, say your ball is rolling towards the hole and that same dog picks it up and runs off with it, then you place the ball on the spot where the dog first picked up the ball. Again, no penalty. The lesson in all this? Don't bring dogs on to the golf course - they might not turn out to be your best friend.

If your moving ball is deflected or stopped by you, your partner or either of your caddies or equipment. you immediately lose the hole in matchplay or, in strokeplay, suffer a two-stroke penalty then play the ball as it lies. The only exception to this Rule is if you are dropping your ball and, say, it hits you on the foot. In that case, there's no penalty and you simply drop the ball again.

There's a big difference if your ball is deflected or stopped by an opponent, his caddie or his equipment. In such instances there is no penalty and you have a choice of either playing the ball as it lies or cancelling the stroke and playing it again.

Note, however, that there is a difference between an opponent (whom you compete against in matchplay) and a fellow competitor (whom you are paired with in strokeplay). The rules relating to a deflected or stopped ball by a fellow competitor or his caddie or his equipment is the same as it is with regard to an outside agency. In other words, it's rub of the green.

There's no penalty when your moving ball hits another ball at rest, except when both balls are on the green before you played the stroke. If that were to happen, you would be penalized two strokes.