The days of green-reading books might be coming to an end -- or at least the days of their effectiveness.
The USGA and R&A have formally unveiled a proposal to be added to the new Rules of Golf in 2019 which significantly scales back the information allowed in a green-reading book, either as it's printed or added in later by a player. The changes will be considered an interpretation of new Rule 4.3.
“Both the USGA and the R&A are committed to the position that a player’s ability to read their line of play on the putting green is an essential skill that should be retained,” said Thomas Pagel, Senior Director, Rules of Golf and Amateur Status for the USGA. “The focus of the interpretation is to develop an approach that is both effective and enforceable.”
In particular, the proposed new language calls for banning information including "subtle features and slopes through the inclusion of many directional arrows, contour lines or numerical slope indicators" on putting greens.
Beginning in 2019, the USGA will only allow detailed contour mapping of greens in areas where the slope is equal to or greater than 4 percent (2.29 degrees). This is designed to limit indicators from areas where a hole is most likely to be cut, which is typically less than 3.5 degrees of slope. This is designed to require the naked eye to do the work required to read a putt.
The size of green books will be limited through requiring the maximum scale to be 0.375 inches to 5 yards.
Meanwhile, handwritten notes will continue to be allowed, as will the traditional information already included in yardage books, including the outline of the putting green and indicative information for ridges and slopes beginning and ending.