HOW IS THE COURSE AND SLOPE RATING CALCULATED?
The USGA Course Rating System is used worldwide to determine these values and is very objective in nature taking into account all the factors that affect the playing difficulty of a course. It requires numerous specific measurements to be taken on each hole of the golf course, which assists in the consistency of application by all course rating teams.
The system is designed to differentiate playing difficulty of all courses relative to each other, which requires a consistent application by the course rating team. It takes account of the actual measured length of a golf course, factors that can affect the playing length and other challenges that influence the playing difficulty of each hole, that is, obstacle factors.
It also evaluates the playing difficulty of a course for a Scratch Golfer and a Bogey Golfer under normal course and weather conditions.
For assessment purposes, a Scratch Golfer is a Female golfer who hits a driver 210 yards and can reach a 400-yard hole in two (second shot being to a maximum of 190 yards) and a Bogey Golfer hits a driver 150 yards with her subsequent shots being hit to a maximum of 130 yards.
The factors that can affect the effective playing length of a golf course however are:
Roll – assessment of how far a ball will roll on fairways with various surface conditions/contouring
Dogleg – where the dogleg design of a hole does not allow a full tee shot to be played
Wind – assessment of average wind strength and direction
Elevation – difference in elevation between the tee and green and for player’s approach shots to the green
Forced Lay-up – where a player is forced to play short of any obstacle(s) that crosses the fairway
In addition, the ten obstacle factors that are used to determine the playing difficulty of a golf course are also assessed:
Topography – nature of the stance and lie within each landing zone and approach shot elevation to the green
Fairway – the width of fairway landing zones, hole length and nearby obstacles – trees, hazards and punitive rough
Green Target – evaluation of hitting the green with the approach shot – visibility and nature of the green surface
Recoverability and Rough – difficulty of recovery if the tee shot landing zones and/or the green is missed
Bunkers – size and depth of bunkers and their proximity to landing zones and greens
Crossing Obstacles – shot length to carry water, punitive rough or ravines for example and proximity to landing zones and greens
Lateral Obstacles – proximity of water hazards, other penalty areas or out of bounds for example from centre of fairways and greens
Trees – size and density, proximity to centre of landing zones/greens, shot length to target areas, recovery difficulty
Green Surface – putting difficulty on a green – green speeds, surface contours and tiers
Psychological – evaluation of the cumulative effect of the nine other obstacle factors. This is purely a mathematical calculation added on after the course rating is completed.
The Rating System then uses table values, adjustments and formulas to calculate ratings.
The Course Rating is calculated from the effective playing length and obstacle factors for the 18 (or 9) designated holes. It is expressed in strokes to one decimal point and represents the expected score for a scratch player. The Bogey Rating represents the expected score for a bogey player.
The Slope Rating is then calculated from the difference between the Course Rating and the Bogey Rating and represents the relative difficulty of a course for a bogey player compared to a scratch player. A course therefore with long carries, narrow fairways, lots of hazards and thick rough will have a high slope rating because these features are more of a challenge to bogey golfers.
Slope Rating can be anywhere between 55 and 155. The neutral value that is used in handicap calculations is fixed at 113 representing a course of standard relative difficulty and the GB&I course average is around 125.
To look up Course and Slope Ratings for any club please click here.
All pretty complicated stuff, but the governing bodies believe this is a well refined method and produces excellent results.
As you can imagine, physically rating a golf course takes a team of 4-5 people approximately half a day and is reliant on good weather. The Course Assessor also has the paperwork to prepare in advance and all the number crunching to do afterwards to complete the assessment before everything is sent to England Golf for confirmation of the rating outcomes.