Is your smartwatch making you cheat without knowing it?
Rule 4.3a is the single rule governing every device, gadget, and training aid you carry on a competition day — from laser rangefinders and GPS watches to alignment sticks, wind gauges, and medical tape. The legal line is more precise than most golfers expect: a first breach costs 2 penalty strokes, a second means disqualification. Here is a category-by-category breakdown of exactly what you can and cannot carry.
The Laser and GPS Hack (DMDs)
Allowed:
- Measure the distance to the flag, hazards, or course features
- Use a compass or direction function
Banned:
- Measure elevation changes (slope) unless a Local Rule expressly permits it
- Have the device recommend a club based on the data
- Use wind functions that interpret how it affects your shot
The key: your device can give you raw data (distance, direction), but it cannot interpret that data for you.
Your Phone on the Course
Allowed:
- Listen to music or podcasts (low volume, without disturbing others)
- Check scores from other sports or competitions
- Make and receive calls (brief, without delaying play)
- Look up the Rules of Golf on the official app
Banned:
- Watching competition videos to choose a club or adjust your swing
- Analysing your tempo or mechanics during the round
- Using apps that interpret course data to recommend strategy
The Wind Hack
Allowed:
- Check the local weather forecast
- Measure ambient temperature and humidity
Banned:
- Using any artificial object to measure wind speed or direction (anemometers, powder, ribbons, grass tossed to gauge wind)
- The classic "toss grass in the air" test is a grey area: if done to precisely read the wind, it technically violates the spirit of the rule
Training Aids: The Mistake Everyone Makes
Many players carry alignment sticks or weighted club covers ("donuts") in their bag.
Allowed:
- Using general stretching equipment (rubber tubes, alignment stick across the shoulders) to warm up
- Doing so before the round or between holes, as long as you don't make a practice swing with them
Banned:
- Making any stroke (practice or real) using a training aid
- Placing an alignment stick on the ground to aim while practising your swing
- Using a non-conforming club for practice
Self-Standing Putters
Some putters (self-standing) stay upright on their own. They're legal to play with, but:
- Legal: executing strokes with the putter if it conforms to the Equipment Rules
- Illegal: leaving it standing behind the ball as an alignment aid. You must remove it before aligning your putt
Medical Hacks: Tape and Protection
Allowed:
- Using medical tape or similar protection for medical reasons (preventing or protecting injuries)
- Wearing gloves on both hands if needed
Banned:
- Applying tape excessively or in a way that locks a joint artificially to improve your swing
- If in doubt, always check with the Committee before starting your round
Golden rule: if a device or accessory gives you an advantage you wouldn't have without it, it's probably banned. When in doubt, ask the tournament Committee before using it.