The complete guide

Sail Race Tracker: open-source, SIM-free live GPS race tracking for youth sailing.

This is the full reference page for Sail Race Tracker — what it is, who built it, how the hardware and software fit together, what it costs compared to commercial systems, and the awards and press that recognised it. Designed and built by Jack Harker, ACG Parnell, Auckland, New Zealand.

Sail Race Tracker is a low-cost, open-source, SIM-free GPS race-tracking system for youth sailing dinghies. It uses long-range LoRa radio and a Raspberry Pi to plot every boat on a live web map — bringing professional, America's-Cup-style race tracking to clubs and schools without the cost or subscriptions of commercial systems.
NZ$9,000 Samsung Solve for Tomorrow 2025
 1st, NIWA Science Fair 2025
 Featured on RNZ
What it is

The whole race, visible from the shore.

Youth dinghy racing is fast and tactical, but almost impossible to follow from land — boats are small, far out, and look identical at distance. Coaches can only watch a fraction of the fleet; officials struggle to keep eyes on everyone; and parents see very little. Commercial tracking exists, but it is expensive, subscription-based, and built around phones and SIM cards that are banned in racing and unreliable on the water.

Sail Race Tracker closes that gap. Each boat carries a small waterproof tracker that reads its GPS position and broadcasts it over long-range LoRa radio. The signals are collected on a support boat and a Raspberry Pi, pushed to the cloud, and drawn live on a browser map — complete with boat trails, course marks, headings, a leaderboard and a full replay timeline. It is class-legal, needs no mobile data, and can be built for a fraction of the price of off-the-shelf systems.

Sail Race Tracker system overview — boats broadcasting to a LoRa gateway, up to the cloud, and onto a live dashboard watched by a coach and spectators
About the maker

Built by Jack Harker, a youth sailor and self-taught engineer.

I'm Jack Harker, a competitive youth sailor and a student at ACG Parnell in Auckland, New Zealand. I built Sail Race Tracker because I lived the problem myself: the racing I loved was invisible to almost everyone watching from shore, and the technology that solves it only seemed to exist at the very top of the sport.

Over the course of roughly a year, I took the project from a research question to a working, on-water prototype — choosing the radio technology, designing the end-to-end system architecture, wiring and flashing the boards, writing the software, waterproofing the hardware, and field-testing with real clubs. I used AI as a 24/7 research tutor while doing all of the testing, coding and assembly hands-on, and documented every decision, dead-end and breakthrough in a detailed log book.

Jack Harker, the designer and builder of Sail Race Tracker, at the Samsung Solve for Tomorrow awards evening
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documented build iterations
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pages of log book
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words of research & notes
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research to regatta
How it works

From boat to browser, end to end.

The system is a clean pipeline. Each stage uses open-source software and off-the-shelf components, so the whole thing can be rebuilt, audited and extended by anyone.

Fleet of boats connected by a dashed LoRa mesh network to GPS satellites — long-range radio, no SIM card required
  1. 1 · Boat

    GPS tracker on each dinghy

    A waterproof, mast-mounted unit (an ESP32-class board with a LoRa radio and a high-accuracy GPS module) reads the boat's position several times per second.

  2. 2 · Radio

    Long-range LoRa broadcast

    Positions are sent over long-range LoRa radio — no cellular data, no SIM — using a time-slotted (TDMA) scheme so many boats can share the airwaves without collisions.

  3. 3 · Gateway

    Support-boat base node + Raspberry Pi

    A base radio on a support boat receives every fix and passes them over serial to a Raspberry Pi gateway running a small Python service.

  4. 4 · Cloud

    Ingest, store and fan-out

    The gateway posts fixes to a lightweight cloud backend that stores the tracks and fans them out live to connected viewers.

  5. 5 · Dashboard

    Live Leaflet web map

    A browser dashboard plots every boat, its heading and trail, the course marks and start line, a live leaderboard, a wind indicator and a full replay timeline you can scrub and speed up.

Sail Race Tracker system architecture: boat devices to support-boat gateway to Raspberry Pi to web dashboard
The end-to-end data flow: boat → LoRa radio → support-boat gateway → Raspberry Pi → cloud → live web dashboard.
The hardware

Off-the-shelf parts, marine-ready.

Exploded view of the waterproof Sail Race Tracker unit: GPS module, ESP32 board, battery, LoRa radio, waterproof case and 3D-printed mounting bracket
Every tracker in one waterproof unit: GPS, ESP32, battery, LoRa radio and a 3D-printed mast bracket.

LoRa radio boards

ESP32-class boards (such as the LilyGo/TTGO LoRa32) carry a long-range LoRa transceiver and an on-board display for field debugging.

High-accuracy GPS

NEO-M8N GPS modules were chosen for fast fixes and good accuracy — essential for tight, mark-rounding race tactics.

Waterproof enclosure

An IP67-rated case and a custom 3D-printed mast mount keep the electronics dry and steady through spray, capsizes and pool testing.

Raspberry Pi gateway

A Raspberry Pi reads the base radio over serial and relays fixes to the cloud — the bridge between the on-water mesh and the internet.

Rechargeable & SIM-free

Each unit is self-contained and rechargeable, with no SIM card and no data plan — nothing to subscribe to and nothing to renew.

Class-legal by design

Because there is no phone aboard, the system respects the racing rules that ban phones and external aids on the boat.

The software

A live dashboard anyone can open.

The web dashboard is built on Leaflet, with a vanilla-JavaScript engine that draws boat markers as heading-rotated sails, progressive coloured trails, the start line and course marks, a course-derived wind dial, and a live-sorted leaderboard that understands legs, mark roundings and finishes. A playback engine interpolates between GPS samples so replays are smooth, with play, pause, scrub and 2×–30× speed controls.

Behind it, a Python gateway service moves data from the on-water radio mesh to a small cloud backend that stores tracks and streams them live to viewers over WebSockets. The public showcase site itself is a fast, hand-coded static site (HTML, CSS and JavaScript) with an embedded, self-contained version of the live replay viewer — the same one you can try on the Tracker Demo page.

Open the tracker demo
Why it matters

An affordable, open alternative to commercial trackers.

Systems like RaceQs, Sailmon and Yellowbrick are excellent but expensive — typically NZ$500–900 per unit with ongoing subscriptions, and often built around phones or cellular data. For a youth fleet of a dozen or more boats, that cost is out of reach, and phones aren't even allowed in racing.

$0
software & licensing cost (open-source)
No
SIM cards or data plans
No
monthly subscriptions
100%
built from off-the-shelf parts
Who it's for

Four people who finally get to see the race.

Sailors

Replay your own races, compare lines against the fleet, and learn faster from real data instead of memory.

Race officials

See the whole fleet at once — safer racing, clearer starts and finishes, and better-informed decisions.

Coaches

Debrief with hard evidence: who went where, when, and why it worked — across every boat, not just the few you could watch.

Parents & spectators

Follow the action live from the shore, finally able to tell which boat is which and how the race is unfolding.

Recognition & press

Award-winning, and covered in the press.

Sail Race Tracker won 1st Prize (Years 7–10) at Samsung Solve for Tomorrow 2025 — a NZ$9,000 prize pool awarded on 30 October 2025 in partnership with MOTAT and TENZ — and took 1st place in the Technology category at the NIWA Auckland City Science & Technology Fair 2025. It was featured on Radio New Zealand and recognised by Samsung New Zealand and Technology Education New Zealand.

Jack Harker accepting the Samsung Solve for Tomorrow 1st prize cheque for NZ$9,000
Accepting 1st prize — NZ$9,000 — at the Samsung Solve for Tomorrow final, 30 October 2025.

RNZ — Nine to Noon

A Radio New Zealand interview on building affordable, open-source tech for the sailing community.

Samsung NZ — Winners

Featured on Samsung New Zealand's Solve for Tomorrow winners page.

Idealog

"Young Kiwi innovators shine at Samsung's Solve for Tomorrow competition."

MOTAT

"Innovation and creativity on display as Samsung crowns Solve for Tomorrow winners."
FAQ

Frequently asked questions.

How does Sail Race Tracker work?

Each boat carries a small, waterproof LoRa GPS tracker that broadcasts its position over long-range radio. Those positions hop through a radio mesh to a support-boat gateway and a Raspberry Pi, which relays the data to a live web dashboard. Spectators open the dashboard in any browser and watch the whole fleet move around the course in real time — no SIM cards and no subscriptions required.

How much does it cost compared with commercial trackers?

Commercial sailing trackers such as RaceQs, Sailmon and Yellowbrick typically cost roughly NZ$500–900 per unit plus ongoing subscriptions. Sail Race Tracker is open-source and SIM-free, so a club can build trackers from off-the-shelf parts for a fraction of that cost with no monthly fees.

Can you track a sailing race without a phone or SIM card?

Yes. Sail Race Tracker uses long-range LoRa radio instead of cellular data, so each boat needs no phone or SIM. That matters because phones are banned under racing rules and mobile data is expensive and unreliable on the water.

Who built it, and is it open-source?

I did — I'm Jack Harker, a youth sailor and student at ACG Parnell in Auckland, New Zealand. I designed and built it entirely from open-source software and off-the-shelf hardware, so clubs and schools can build and adapt their own.

This covers the essentials — for the full reference, see all 231 questions and answers across every part of the system.

Explore & related

Dig deeper.

See the system in action and read the full story:

Tracker Demo

Replay real GPS race tracks — scrub the timeline and follow the leaderboard.

The Build

The hardware, software and field-test story in full.

Story & Press

The award, the press coverage and the year-long journey.

The film

The Samsung Solve for Tomorrow film — the problem, the build, and the system on the water.

Parley

An iPad app that helps non-speaking people take part in real-time conversation, in their own voice. Find it at parley.help.

A related project worth supporting — Parley (parley.help), an assistive-communication iPad app that lets non-speaking people stay in the conversation, in their own voice. Questions, or want to bring Sail Race Tracker to your club? Email info@sailracetracker.live.

See it for yourself

Try the tracker demo, then read the full story.

Replay real race tracks on the demo dashboard, or see how a school project became an award-winning system.

Open the Tracker Demo Read the story & press