Quantifying the total area for hole locations is a key factor in the design process of a golf green, both for new developments and green renovations. A small area for hole positions, not only reduces the variability of pin positions for the golfers, but also limits traffic distribution in the green, leading to poor turf recovery. Parallelly, average green speeds have increased during the last 40 years (from 5 – 6 ft to 10 – 11 ft), so that greens that originally offered 15-20 green hole locations, today only offer 4-5 fair positions, and therefore leads to serious problems regarding its use and maintenance. This fact is becoming very common, particularly in historic clubs, where greens were designed to perform with much slower green speeds.
Recently, we completed a 3D modelling and technical study of several greens in Real Club de Golf de Tenerife, in the Canary Islands. The aim of the study was to carry out an in-depth analysis of the green contouring and the slopes, so that the available area for conforming hole locations could be determined objectively, and with this information, evaluate if the resulting area was large enough to provide with variability and good playing conditions.
For this, we carried out a high precision topographic survey using a laser scanner, and processed the data applying a slope characterization criterion on the green surface. Thanks to this procedure, we obtained solid conclusions that proved to be very useful to the Club.
Area and slope analysis on greens
In order to understand if a given zone of a green constitutes a conforming hole location, there are many available references. However, it is specially useful Mr. Jerry Lemons (ASGCA) article “Putting Green Speed, Slopes, and Non-Conforming Hole Locations”, that includes the maximum slope for green speeds graph. This graph represents the relationship between green speed (ft on the stimpmeter), and the slope to evaluate (degrees). According to Mr Lemons, a green area can be divided in 3 ranges for a given green speed:
- In the red zone “critical slope”, the slope is excessive, and the ball will roll uncontrolled. Hole positions here will classify as non-conforming. Also, no hole positions are conforming any closer than 3m to this slope.
- In the yellow zone, the slope falls between excessive and adequate, and is considered to be “marginal”. A hole location will only be conforming if there is a consistent slope 2.4m around the hole.
- In the green zone, the slope is adequate, and is considered to be “recommended”. A conforming hole location should have more than 90cm of consistent slope around it.
Relationship between green speed and putting green slope. Mr. Jerry Lemons. USGA green section record 2008.
Green speed vs. slope analysis
Also, it shall be highlighted that based on a given green speed, these limiting slopes that define the ranges will vary. For example, in Real Club de Golf de Tenerife, the selected green speed was 9 feet, so that, we defined the slope ranges as per:
The following figure is an example of a plan where the different slope ranges are represented in a given green. It also incorporates a table that includes two reference area values: the existing green area, and the potential cupping area for a hole location. The potential cupping area is the resultant area from deducting 3m to the perimeter of the existing green area (R&A and USGA recommendations).
Green slopes analysis plan
Minimum green area for conforming hole locations
Besides, to come to the right conclusions, it was also necessary to determine what was the minimum required pinnable area. According to Mr. Lemons, this will depend on 2 factors:
- Variability of pin positions to make the course enjoyable for regular play (it is recommended to count on at least with 7 pin positions).
- Turf recovery from traffic. The aim of every Club is to always deliver great playing conditions. Therefore, a deeper analysis should be carried out. Other factors such as the number of rounds per day, the established turf species and cultivar, climate, etc. should be taken into consideration. In this case, it was decided that the worst-case scenario accounted for a change of pin position every 2 days, with a turf recovery period of 14 days.
According to Mr Lemons, the area of influence of a golf hole is 18,5 m2. In this case scenario (minimum 7 pin positions, 2 days pin change and 14 days of turf recovery), the minimum pinnable green area was 129,5 m2.
By applying this methodology, we can anticipate if there are size and slope limitations in the design process of a new green, so that potential problems can be avoided.
The methodology is also very useful for golf clubs that are considering a renovation project for their greens, and want to verify objectively if they have enough pin positions to make them enjoyable and offer the best playing conditions.