How the caddie thinks
Drop The Hands is Matt Edmund's AI golf caddie. On a real hole it works with no signal: GPS on the phone finds you, Golf Course Atlas has already rebuilt the hole as checked geometry, it takes in your clubs, your miss pattern and the wind, plays your shot 3,120 times (13 aim lines, 240 shots each), picks one club and one aim, and only then lets the language model put that answer into words. Interactive story: https://33prime.io/caddie.html
The story walks through one real shot: hole 5 at Rio Pinar Golf Club in Orlando, a par 4 of 400 yards from the black tee, from the fairway 150 yards from the middle of the green.
1. No signal, no problem
Out on the course the bars drop. The caddie doesn't need them: the course, your clubs and the engine are already on the phone.
2. GPS on board
The phone's own GPS puts you on the fairway, 150 yards from the middle of the green (138 to the front, 160 to the back). No internet needed.
3. The hole, rebuilt from Golf Course Atlas
Golf Course Atlas maps every edge of a hole: the fairway, tees, water, bunkers and green, plus the fairway's width at each point along the centreline (27 to 32 yards wide on this hole). A physical-sanity validator blocks anything that couldn't exist. The caddie rebuilds the hole from that geometry.
4. Your clubs
Real carries, club by club. In the story the bag is the engine's real test bag: driver 232, 3 wood 215, hybrid 192, 4 iron 182, 5 iron 172, 6 iron 162, 7 iron 152, 8 iron 140, 9 iron 128, PW 116, GW 102, SW 84.
5. Your misses
The engine plans for the shot you actually hit. For a 12 handicap the 7 iron spreads about 12 yards left and right and 9 yards long and short, and comes up about 3 yards short on average. Dispersion is set by handicap tier, and widens from rough or sand.
6. The air
Wind and temperature change how far the ball goes. Headwinds cost about 0.8 yards per mph, tailwinds give back about 0.5, and a crosswind about 0.2. In the story a 6 mph crosswind on an 80 degree day makes the 150-yard shot play 149.
7. Thirteen aims
The engine doesn't just aim at the flag. It tries thirteen lines, three yards apart, from 18 yards left to 18 yards right.
8. 3,120 shots
240 simulated shots down every line (a seeded Monte Carlo, so the same answer every time), each landing somewhere real: sand, rough, water or the green.
9. One call
The line that leaves the fewest expected strokes wins (a strokes-gained model), with extra weight against trouble, and a rule-based club policy never asks for a carry the player can't make. On this shot the engine's call is a 7 iron aimed 3 yards right of the middle of the green: 117 of 240 shots finish on the green, none in the water, 2.44 strokes to finish. Aiming left brings the lake into play (52 of 240 wet at 18 yards left). The club and the aim go to the phone and the Apple Watch.
10. Then the model talks
The language model only puts the engine's answer into words. A live contradiction guard stops it from saying a number the engine didn't give it. The engine is written in Rust and gives bit-identical answers on the iPhone (arm64) and the server (x86), checked against 53 golden test cases.
What's real in the story
The hole geometry, tees, hazards and green are real Golf Course Atlas data, shown on the real USDA aerial and USGS terrain. The club, the aim and all 3,120 simulated shots are the real Drop The Hands engine (v0.1.35) run on this lie, with the engine's test bag and miss pattern. The pin is shown at the middle of the green, and the player and the weather are an example.
- Drop The Hands: https://dropthehands.ai
- Golf Course Atlas: https://golfcourseatlas.io