Domain glossary

Definitions in the order an analyst is likely to need them. Each entry gives the term, what it means, typical units or range, and why it matters for analysis.

The course and scoring

Slalom course

A permanent floating course of 6 turn buoys in a zigzag pattern, plus entry and exit gates. The boat runs a fixed centerline path; the skier must ski outside each of the 6 turn buoys in sequence. A “completed” pass clears all 6 buoys cleanly.

Pass

One attempt through the course. A pass is defined by boat speed and rope length (lineOffUs). Scoring is by buoy count — how many buoys the skier cleared before falling, missing a buoy, or running out of course.

Set

A series of passes in one outing, logged together. Typical set: 2–4 passes; max is usually 6. A set also captures equipment and environmental context (boat, site, ski, fin) that usually doesn’t change mid-session.

Buoy count (buoyCount)

How many buoys the skier cleared, from 0 to 6. Quarter-buoy increments allowed, limited to .00, .25, .50 (no .75). Common values:

• 6.00 — pass completed.
• 5.50 — reached the 6th buoy but missed it on the outside.
• Non-integer values reflect partial turn execution at the moment of fall.

Line length / “line off” (lineOffUs)

Rope length expressed as feet shorter than the longest rope (75 ft / 22.86 m). Stored as a positive number (e.g., lineOffUs: 32), conventionally said as “minus 32 off”. Standard shortening schedule in feet:

15, 22, 28, 32, 35, 38, 39.5, 41, 43

A value of 15 means 60 ft of rope remaining; 43 means 32 ft — extraordinarily short, world-class level. The absolute rope length in meters is also stored as ropeLengthAbs.

Progression is the primary measure of improvement. A skier shortening from 28 to 32 is a bigger milestone than gaining a couple of buoys at a fixed line.

Boat speed (speedMph, speedKph)

Speed of the tow boat through the course. Competitive top speeds:

• Men: 34, 35, or 36 mph.
• Women: 32, 34, or 36 mph.

Skiers usually ramp to their maximum speed and then progressively shorten the line from there.

Boat and equipment

Boat setting (“ZeroOff”: boatSetting)

Modern tournament ski boats use “ZeroOff” cruise control, which has named settings controlling how aggressively the boat accelerates and holds speed through the skier’s pull. Represented as a { letter, number, plus } triple:

• letter: A | B | C — acceleration profile (A = smoothest / slowest response, C = most aggressive).
• number: 1 | 2 | 3 — sub-setting within the letter.
• plus: boolean — a “plus” variant (e.g. A1+). Available on newer boats.

Same letter+number across sets is comparable; different settings may meaningfully change pull quality.

Boat brand (boatBrand)

One of "MasterCraft", "Nautique", "Malibu", "Other", or null. The three named brands cover the vast majority of tournament skiers.

Division (divisionSnapshot.divisionCode)

Tournament age/gender category. Examples: "Men 1", "Men 2", "Women 1", "Boys 3". Each division has a maximum allowable boat speed (maxSpeedMph) — e.g., Men 1 = 34 mph, Men 9 = 30 mph. The division is snapshotted at the time of each set/pass, so historical records reflect the division in effect at the time, not the current age-driven division.

Open-rated (openRated)

A skier can elect to be “open-rated” regardless of age, running the full maximum speed (36 mph for men / 34 mph for women) instead of their age-division cap. Aspirational skiers stay open-rated; older skiers often switch to their age division for more competitive results.

Practice vs tournament (isPractice)

Every set is either practice or tournament. Tournament sets populate tournamentName, tournamentDate, and tournamentRound. Practice sets leave those null.

Ski and fin settings

Small changes to fin geometry meaningfully alter how a ski turns. Analysts often look for correlations between fin changes and performance changes.

Fin DFT (skiSettings.finDftIn / finDftMm)

Distance From Tip — how far forward the fin is mounted from the ski tip. Typical range: 0.700–0.850 in (~17.8–21.6 mm). A change of 0.005 in is perceptible.

Fin depth (skiSettings.finDepthIn / finDepthMm)

How far the fin extends below the ski base. Typical: 2.40–2.60 in (~61–66 mm). Deeper = more hold, less manoeuvrability.

Fin length (skiSettings.finLengthIn / finLengthMm)

Chord length of the fin. Typical: 6.70–7.00 in (~170–178 mm).

Wing angle (skiSettings.wingDeg)

Angle of the fin’s wing in degrees. Typical: 5–9°. Affects deceleration through the wakes.

Boot type (skiSettings.bootType)

• "double" — two boots, both feet fixed in hard shells.
• "rtp" — Rear Toe Plate: front boot fixed, rear foot in a soft toe plate. Traditionally the dominant setup; double-boot has grown among elite skiers.

Account-level settings

Units (account.unitsMode)

"US" (mph, inches) or "METRIC" (kph, mm). This is a display preference. All measurements are stored in both units regardless. For cross-skier or cross-device comparison, prefer the metric versions to avoid rounding drift.

Season window (seasonStartMonthDay / seasonEndMonthDay)

MM-DD strings defining the skier’s “season” — the window across which the app groups stats. Example: "03-01" → "11-30" for a northern-hemisphere outdoor skier. May wrap year boundary.