Trivial

Make pursuit trivial. A lightweight, offline-first pursuit race start timer for UK sailing clubs, using the RYA Portsmouth Yardstick (PY) handicap system.

A race officer can set up and run a pursuit start sequence in under a minute, on a phone, in wind and rain — no login, no backend, works fully offline.

This is still very much a WIP, please contact me for more info

See trivial-spec.md for the full product specification and the Stage 1 decision record (§10).

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User guide (for the race officer)

Set up a race — under a minute

1. Open the app. Your last race (classes, duration, start sequence) is restored. On first use the fleet starts empty.
2. Pick your fleet. Tap classes to add or remove them; search by name. Tap the ★ on any class to save it as a favourite — favourites appear first and are pre-selected next time. There's no limit on how many classes you select.
3. Set the race duration with the +/− stepper (minutes). This is the total race window — first gun to finish — and it sets how far apart the starts are.
4. Choose the start sequence: 5-4-1 (5-minute) or 3-2-1 (3-minute).
5. Check the schedule preview. Each class shows its PY and start time as +m:ss from the first gun. The slowest boat starts first (+0:00); the fastest (scratch) starts last and chases the fleet down.
6. Tap Start Race.

Run the race

• Start sequence. Tapping Start begins the countdown immediately. The big number counts down to the first gun and milestone badges light at 5 / 4 / 1 (or 3 / 2 / 1) minutes — sound your signals as usual.
• First gun. At zero the screen flashes GO — sound the horn once; the slowest class is away.
• Each class start. The display counts down to the next class, turns amber in the final 10 seconds, then flashes GO — one horn per class. Classes that share a PY start together on a single GO.
• Master clock. The top bar shows elapsed race time and time to finish (finish = first gun + duration; the slowest boat sails the full window and everyone converges there).

Add a latecomer mid-race

Someone turn up after the start? Tap + Boat (top of the timer) to open the Fleet screen, then tap their class:

• If their start hasn't passed yet, they drop straight into the queue at the right time — even a boat faster than the scratch, which simply starts at the back and chases.
• If their start has already passed, a big START NOW alert tells you to send them across the line immediately.

Existing starts never move when you add a boat. You can also remove a class that hasn't started yet; started classes are locked. Tap Back to race to return to the timer.

Controls

• Pause = postponement (AP). Freezes the clock; on Resume, every start still to come — and the finish — shifts later by however long you were paused. Classes that have already started are unaffected.
• Reset (press and hold) — re-arms to the start of the sequence, paused and ready to go again with the same fleet, e.g. after a general recall.
• Stop (press and hold) — ends the session and returns to setup.
• Reset and Stop require a deliberate press-and-hold so they can't be triggered by accident in the cold or wet.

Race-day tips

• Keep the timer screen open — it holds the screen awake (Wake Lock) so it won't sleep mid-sequence.
• Load the app once on wifi before going afloat; it then works fully offline.
• Add it to your home screen for a full-screen, app-like experience.
• The class list is locked once a race is running — tap Stop first if you need to change it.

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Stack

• Next.js (App Router, output: 'export' static export) — deploy to Vercel
• TypeScript throughout (no any), Tailwind CSS (dark "instrument" theme)
• Zustand (+ persist) for state, Serwist for the offline PWA
• Vitest for the calc/timer engine

How the timer works

• Start-sequence phase counts to the first gun using the chosen standard countdown — 5-4-1 (signals at 5:00 / 4:00 / 1:00 / GO) or 3-2-1 (3:00 / 2:00 / 1:00 / GO). The sequence is the lead-in; tapping Start begins it immediately.
• Race phase shows a plain countdown to each class's start; a brief GO flash cues the officer to sound the horn once per class.
• The clock is wall-clock anchored (Date.now() against stored anchors), so it survives backgrounding and throttling. Pause is a postponement that shifts all remaining starts later.
• Classes sharing a PY are grouped into one start. Finish = first gun + duration.

Start formula (spec §2.2): start = duration × (1 − PY_class / PY_slowest), measured from the first gun and anchored on the slowest boat, so boats sailing to handicap converge at the finish.

Develop

npm install
npm run dev        # http://localhost:3000
npm test           # calc + timer engine unit tests
npm run build      # static export to ./out (Serwist SW bundled)
npm run lint

Licence

GPL-3.0-or-later. PY data © RYA Portsmouth Yardstick Scheme (2026 list, v4).