There seem to be so many different formulas when it comes to getting out of rough I thought I would share my philosophy in an attempt to simplify your approach. It all really depends on the quality of the lie, because even in very long rough, it's still possible to get decent access to the back of the ball.
Here are a few examples:
In this situation the clubhead needs to get so far down into the thick grass that most of the velocity created in the swing will be dissipated. The challenge here is not only getting the clubface on the ball, it is getting the ball over/through the grass in front of it. I would always use a very lofted club here (9 iron max) and plan on getting the ball back in play. Hit down more by moving the ball slightly back in your stance and thus steepening the angle of attack and do not be greedy here.
In this scenario the ball is perched on top of the longer grass and we're smiling. Be careful though as this is a perfect lie for a flyer. A flyer occurs when the grass does not slow the clubhead down through the hit and just enough of it gets caught between the ball and the face. As this grass/matter fills the grooves at impact and gets trapped between the ball and the face, there is very little grip on the ball and as a result the ball launches closer to the dynamic/delivered loft (higher) and spins very little. Ever heard of "high launch, low spin"? That's what we're looking for with our driver, but not with an 8 iron from 130 yards and explains why you airmailed the clubhouse from the 9th fairway last week.
With this type of lie also watch for hitting under the ball. When it's perched on top of the grass like this try to view it as being on a high tee - an easy one to swing under! Make your practice swings where you just brush the very top of grass and duplicate that during the actual shot.
This is a tough one - it doesn't look bad, yet the hard part is deciding which way it will come out. It could be hot, yet it could also come out very soft and dead like the first example. The best thing you can do here is take a few extra seconds to assess the lie and then commit fully to your decision. Make the call and be committed.
When hitting out of very long grass (ankle/knee high) remember that the long blades of grass will get to the shaft and hosel first. As they wrap around this lead part of the club it will slow down dramatically, causing the face to deloft and the toe of the club to close. Notice how hard Phil Mickelson is working to keep the face from closing in the picture at the top of the page. Having hit out of the fescue more than a few times at Atlantic Golf Club this summer I know this for a fact - take a lofted club, aim a little right, swing hard and don't ever be greedy.
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