Triangulate trebuchet landing distance from two observation stations — spotters read one angle each, no math required on their end.
How this works: a plain-language guide and the math
Create an event to start tracking shots, or select an existing one to collaborate with spotters in real time.
Connecting to event...
Enter this event's shared password to change setup, trebuchets, or shots. You can still view everything below.
Enter latitude/longitude for Station A & B (or tap Capture GPS while standing at the station). Optical theodolite/angle measurements remain the authoritative calculation for competition scores; GPS coordinates provide a visual satellite map overlay and sanity check.
Stations A and B need a clear view of the entire target area. One pair covers every trebuchet. At each station, zero an angle-sighting device (large protractor on a stake, or a phone sighting app) toward the other station — that's 0°. Compass bearings work too but are less reliable near metal trebuchets.
For each trebuchet, measure its distance from Station A and the angle from the A→B baseline to the trebuchet (sighted from A; positive angles sweep into the target area, negative angles down to -180° sweep behind the baseline).
Stand at Station A. Aim toward Station B to set 0°, then turn toward the trebuchet. Enter the angle between those two sight lines. Angles into the target area are positive; angles behind the A–B baseline are negative (down to -180°). This is the trebuchet's position angle, not its launch angle.
| Name | Dist. from A | Angle | |
|---|---|---|---|
| No trebuchets added yet — you can still log shots measured from Station A directly. | |||
Stand at Station A. Aim toward Station B to set 0°, then turn toward the impact. Report the angle between the A→B sight line and the A→impact sight line, with the corner at A. Do not measure from the trebuchet or use an absolute compass bearing. Example: a quarter-turn from B toward the impact is 90°.
Stand at Station B. Aim toward Station A to set 0°, then turn toward the impact. Report the angle between the B→A sight line and the B→impact sight line, with the corner at B. Do not measure from the trebuchet or use the A→B direction as your zero. Both impact angles must be greater than 0° and add up to less than 180°.
| Shot | Trebuchet | ∠A | ∠B | Distance | Baseline check | Error | Ballistic weight | Counterweight | Finger angle | |
|---|---|---|---|---|---|---|---|---|---|---|
| No shots logged yet. | ||||||||||
Select a shot to inspect its distance and readings.
Station A (launch) is fixed at left, Station B at right, impact points plotted per shot. Not to a fixed scale between shots and setup card — for a visual sanity check only.