Welcome to MythBusters, a Golf Digest+ series where we explore answers to some of golf’s most common questions through a series of tests with golfers and robots. Sometimes definitive, other times less so, our findings aim to shed new light on topics that have consumed golfers for years.

How much does long, thick rough affect distance? From a golfer’s experience, we know that hacking out of healthy rough is an inherently imperfect science. Sometimes the ball comes out normal, sometimes far from it. And then there’s those flyer lies, where the ball actually travels farther than normal.

With U.S. Open at Oakmont Country Club, we’re not interested flyers. Instead, we set out to determine how much shorter the ball travels from average to poor lies in long, thick rough.

MORE: The 18-hole hazard—The U.S. Open rough makes Oakmont both impossible and simple

Our test

For our test to determine thick rough’s effect on distance, two Golf Digest staffers—Drew Powell (+2.3 Handicap Index) and Sam Weinman (11.2 Index)—hit a series of shots with a 9-iron and a 6-iron out of thick rough and the fairway. We used two golfers with different swing speeds in order to show how rough’s impact might change at different speeds.

Powell and Weinman alternated hitting six shots from the fairway and six from the rough (after dropping from knee height) with each club. For this test, we’re mostly focused on distance, so we measured the carry and total distance each ball traveled.

We conducted the test at Brooklawn Country Club in Fairfield, Conn., an A.W. Tillinghast design which has hosted five USGA championships and is most sternly defended by its penalizing rough and greens. Under superintendent Benjamin Goossenn, the rough at Brooklawn in early June is among the toughest the course will see all year.

Before we get into the results, one quick note. Our test does not seek to replicate the effect of Oakmont’s rough at the U.S. Open. Even with Brooklawn’s tremendous condition, it’s still not at U.S. Open levels. Rather, we aim to provide relevant context for everyday golfers who wonder how much distance they might lose out of long rough.

What we found

For the 9-iron portion of the test, Powell hit an approximately 160-yard approach into the green on Brooklawn’s 12th hole. From the fairway, Powell’s average carry and total number was 153 yards, while from the rough, he carried the 9-iron only 135.2 on average, 17.8 yards less than from the fairway.

Weinman hit on the same hole from approximately 120 yards and experienced similar results, losing nearly 13 yards of carry distance from the rough. As you can see with both Powell and Weinman’s results, the shots hit from the rough didn’t roll much in this example because they landed in greenside rough.

To test rough’s effect on 6-iron distance, Powell and Weinman moved to the 18th hole, where Powell hit approaches from about 185 yards. Again, he lost significant carry distance from the rough. Weinman hit from 135 yards and found similar results. While both players carried the 6-iron shorter from the rough, both saw an increase in total distance from the rough versus the fairway. This was due to the increased roll-out that they experienced from the rough. Since you can run the ball up short of the 18th green at Brooklawn, Powell and Weinman’s shots from the rough rolled many yards.

What it means

What’s most clear from our test results is that long, thick rough decreases carry distance. In our test, we saw a loss of carry distance range from seven to 18 yards with a 9-iron and 6-iron. How far the ball will travel in total, though, is a different question that depends on the hole. Shots hit from the rough will tend to spin less and roll more, so if you can roll the ball up to the green, then you might find that shots from the rough travel just as far as those from the fairway. If you have to carry a hazard, bunker or rough, you won’t benefit from that increased roll-out.

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How much distance can you expect to lose from the rough? That’s where it becomes a very imperfect science. Why did the shots with a 9-iron lose more distance from the rough than the 6-iron shots? Though the rough was long and thick in both areas, the grass on the 12th hole (where the 9-irons were tested) was especially brutal. It’s likely that this thicker rough caused more of an effect than the rough on the 18th hole.

What it doesn’t mean

As we just mentioned, our test does not show that each time you have a bad lie in the rough with a 9-iron, you can expect the ball to travel 17 yards shorter. This test demonstrates more broadly the effects of rough on distance. What we do clearly show is that an average to poor lie in long rough will fly shorter, oftentimes much shorter. For you to accurately determine how much shorter, it’s critical to analyze the lie. How far down is the ball sitting down? Is there a lot of grass behind the ball? How long and thick is the rough?

Also be sure to consider the wind. Since shots hit from the rough tend to spin less, they can often pierce through a headwind better than a shot hit with more spin from the fairway. Our results show this. When Powell and Weinman were hitting their 6-irons, the wind picked up a little harder into their faces. Shots hit with more spin from the fairway can balloon easier, whereas those hit with less spin from the rough can have a more penetrating trajectory.

LIE DETECTOR: The tricky into-the-grain chip

Like we said, this is all an imperfect science that even the best players in the world must resort to making an educated guess on how each of the different factors will affect how the ball flies out of rough.

Verdict

Shots hit from average to poor lies in the rough will fly shorter than those hit from the fairway. How much shorter is determined by numerous factors including the lie, the rough height and thickness, the club and the wind.