Rules for Getting Course Information: One Wrong Tap on Your Phone Can Be a Rules Breach

During a round, it’s natural to want to know distance, wind, or slope. But how you use equipment to get that information can breach Rule 4.3a(1) and lead to penalty or disqualification. With a smartphone in your pocket, one wrong tap can be a breach.

Where the Line Is

The rules allow measuring straight-line distance between two points. They do not allow measuring “what is happening right now on the spot” with a device.

• OK: Information obtained before the round and handwritten notes (wind notes from practice rounds, club-used records, green lines copied from TV or past data).
• NG: Live wind measurement, phone level app for slope, real-time wind overlay on the course map, etc.

Having an app on your phone alone is usually not a breach. Activating a function that gives you “current values at that location” is a breach.

Common Breach Causes in Competition

Statistically, slope function use, wind/wind-direction apps, club recommendation, and slope analysis are among the main penalty causes. How you use the slope switch on a laser rangefinder, and attaching oversized paper to a yardage book, can also lead to non-conforming equipment and disqualification.

Yardage Book Physical Specs

You may write as much as you like from your own information. Attaching paper larger than the permitted size (4.25×7 in / ~10.8×17.8 cm) is prohibited. Everything must fit within the book dimensions.

For a full OK/NG list, violation stats chart, NG case studies, and yardage book dimensions, see the LAB report “Rule 4.3a(1) DMD & Yardage Book”.

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Read in LAB: Rule 4.3a(1) DMD & Yardage Book