Mark Long's book is invaluable for Open contestants

A yardage book small enough to fit in a player's back pocket or a caddie's bib is seen dozens of times during the telecast of a golf tournament, and will be noticed far more this week as players and caddies try to decipher shots and putts over the East Course at Merion Golf Club.

The book used at this year's U.S. Open is the work of Mark Long, who spent more than 30 hours at Merion starting last weekend making adjustments to the information he already had compiled for the 2005 U.S. Amateur, and updated before the 2009 Walker Cup. It's a collection of target lines where players take aim, along with angles and distances.

"If I gave them that [2009] book, they'd be fine," Long said. "The tee shots are so complicated because of the lines. I think I'm making it more complicated, especially on the six holes with blind tee shots. But I put a lot of work into making them precise.

"There are quite a few changes from last summer. They widened No. 2 [fairway] to the left, moved No. 11 to the left. They're always tweaking things a bit."

Long, 49, of Ponte Vedra, Fla., spent more than 20 years working as a caddie on the PGA and Champions Tours, working mostly for Fred Funk. He put together his first U.S. Open yardage book in 2000 at Pebble Beach.

A few years later, the U.S. Golf Association decided to utilize his services, and now Long makes up the book that is given to each contestant when he registers for the Open. He also organizes yardage books for nearly every tournament on the PGA Tour, as well as the PGA Championship, Ryder Cup, and U.S. Women's Open.

Long, who started out as an aerospace engineering major at Maryland before switching to economics, walks the course with two laptop computers and software packages, including programs for measuring and drawing. He said he put in more than 20 hours of computer time to finish the Merion book.

He also plans to complete a book charting Merion's greens and sell them. He said he sold 52 during last year's U.S. Open at the Olympic Club in San Francisco.

The older yardage books were on hand at Merion for those who wanted to scout the course in advance. Long said he received a text from Joe LaCava, the caddie for Tiger Woods, to make sure one existed when he toured the course on May 27, the day before Woods played his first practice round there.

LaCava added to the book with the help of Merion assistant pro Sean Palmer and club member Buddy Marucci, who walked the practice round with Woods.

Long set up his first yardage book at a U.S. Open qualifier - he thinks it was 1989 or 1990 - and he gradually became more interested.

The earliest measuring methods, such as the surveying wheel, were "really primitive," he said. In later devices such as lasers and range-finders, he found "the accuracy wasn't up to it," so he turned to professional surveying equipment.

He said the newer equipment measures elevation changes that can help with different types of shots.

"I don't think I should tell somebody how far the shot should play for them," he said. "I just want him to know how far out and how much downhill it is. A lot of people who use those lasers don't understand that."

After receiving their yardage book, caddies and players make notations as part of their plans for the competition.

"No matter how thorough you think you make it, it's not going to fit everything that everybody wants," Long said. "There's an infinite number of tee-shot lines. Some caddies like the basic information, but some include every little thing."